International Journal of Powder Metallurgy Volume 45 Issue 1

1-Page View

2-Page View

Search

Table of Contents

Next

e-version

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Here’s how easy it is to use the e-version of the International Journal of Powder Metallurgy with these built-in navigation buttons Use this button to go to the previous page

Use these buttons to toggle between a 1-page view (shown below) and a view of 2 facing pages

Use this button to go to the next page

Use this button to go to the table of contents of this issue, from where you can go anywhere with a single click

Use this button to access the most powerful feature of the e-version of the Journal: the search capability. In some versions of the Adobe Reader, clicking this button will bring up the following window:

If this is the case, click on the arrow next to “Find:” and then click on “Open Full Reader Search” which will bring up the following window:

Type in the term you want to search for, click on the “Search” button, and the results will include every instance of the term in the current issue.

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Previous

1-Page View

EDITORIAL REVIEW COMMITTEE P.W. Taubenblat, FAPMI, Chairman I.E. Anderson, FAPMI T. Ando S.G. Caldwell S.C. Deevi D. Dombrowski J.J. Dunkley Z. Fang B.L. Ferguson W. Frazier K. Kulkarni, FAPMI K.S. Kumar T.F. Murphy, FAPMI J.W. Newkirk P.D. Nurthen J.H. Perepezko P.K. Samal H.I. Sanderow, FAPMI D.W. Smith, FAPMI R. Tandon T.A. Tomlin D.T. Whychell, Sr., FAPMI M. Wright, PMT A. Zavaliangos INTERNATIONAL LIAISON COMMITTEE D. Whittaker (UK) Chairman V. Arnhold (Germany) E.C. Barba (Mexico) P. Beiss, FAPMI (Germany) C. Blais (Canada) P. Blanchard (France) G.F. Bocchini (Italy) F. Chagnon (Canada) C-L Chu (Taiwan) O. Coube (Europe) H. Danninger (Austria) U. Engström (Sweden) O. Grinder (Sweden) S. Guo (China) F-L Han (China) K.S. Hwang (Taiwan) Y.D. Kim (Korea) G. L’Espérance, FAPMI (Canada) H. Miura (Japan) C.B. Molins (Spain) R.L. Orban (Romania) T.L. Pecanha (Brazil) F. Petzoldt (Germany) G.B. Schaffer (Australia) L. Sigl (Austria) Y. Takeda (Japan) G.S. Upadhyaya (India) Publisher C. James Trombino, CAE [email protected] Editor-in-Chief Alan Lawley, FAPMI [email protected] Managing Editor James P. Adams [email protected] Contributing Editor Peter K. Johnson [email protected] Advertising Manager Jessica S. Tamasi [email protected] Copy Editor Donni Magid [email protected] Production Assistant Dora Schember [email protected] President of APMI International Nicholas T. Mares [email protected] Executive Director/CEO, APMI International C. James Trombino, CAE [email protected]

2-Page View

Search

Table of Contents

Next

international journal of

powder metallurgy Contents 2 4 6 9

45/1 January/February 2009

Editor’s Note PM Industry News in Review PMT Spotlight On …Zachary Z. Zebrovious Consultants’ Corner David Whittaker

ENGINEERING & TECHNOLOGY 13 Engineering the Green State of Powder Products D. Whittaker

RESEARCH & DEVELOPMENT 19 Optimization of Metal Powder-Mixing Parameters for Chemical Homogeneity and Agglomeration N. Vlachos and I.T.H. Chang

29 Effect of Axial and Radial Metal Powder Mixing on Chemical Homogeneity and Agglomeration N. Vlachos and I.T.H. Chang

OUTSTANDING TECHNICAL PAPER: PM2008 WORLD CONGRESS 38 Development of a Dual-Phase Precipitation-Hardening PM Stainless Steel C.T. Schade, T.F. Murphy, A. Lawley and R.D. Doherty

HISTORICAL PROFILE 47 The Origin and Role of APMI International in North America’s PM Industry K.H. Roll

DEPARTMENTS 57 APMI Membership Application 58 Web Site Directory 64 Advertisers’ Index Cover: APMI Executive Director Kempton H. Roll addressing an APMI luncheon at the 1963 conference at the Sheraton-Cadillac hotel in Detroit. The International Journal of Powder Metallurgy (ISSN No. 0888-7462) is a professional publication serving the scientific and technological needs and interests of the powder metallurgist and the metal powder producing and consuming industries. Advertising carried in the Journal is selected so as to meet these needs and interests. Unrelated advertising cannot be accepted. Published bimonthly by APMI International, 105 College Road East, Princeton, N.J. 08540-6692 USA. Telephone (609) 4527700. Periodical postage paid at Princeton, New Jersey, and at additional mailing offices. Copyright © 2009 by APMI International. Subscription rates to non-members; USA, Canada and Mexico: $100.00 individuals, $230.00 institutions; overseas: additional $40.00 postage; single issues $55.00. Printed in USA by Cadmus Communications Corporation, P.O. Box 27367, Richmond, Virginia 23261-7367. Postmaster send address changes to the International Journal of Powder Metallurgy, 105 College Road East, Princeton, New Jersey 08540 USA USPS#267-120 ADVERTISING INFORMATION Jessica Tamasi, APMI International INTERNATIONAL 105 College Road East, Princeton, New Jersey 08540-6692 USA Tel: (609) 452-7700 • Fax: (609) 987-8523 • E-mail: [email protected]

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EDITOR’S NOTE

I

t’s time to celebrate on the occasion of the Golden Anniversary of APMI International. Founding Executive Director Kempton H. Roll traces the intriguing history of this unique international professional society from its birth in 1959 to the present. In his inimitable style, Kemp chronicles the events leading to the formation, growth, and importance of the society to the PM industry. This is the 16th year of the MPIF Outstanding Technical Paper Award competition. The recipients of the award, selected by the Federation’s Technical Board from the PM2008 World Congress technical program, are from the Hoeganaes Corporation and Drexel University. Their collaborative study details the development of a dual-phase precipitation-hardening stainless steel. A unique feature of the new low-cost alloy is its ability to increase in both strength and ductility on aging. We extend a welcome to David Whittaker, chair of the Journal’s International Liaison Committee, in the “Consultants’ Corner.” Topics addressed embrace future prospects for PM titanium applications and guidance to end-user designers on high-performance press-and-sinter parts. Kudos to Animesh Bose, the 2009 APMI Fellow Award recipient. A long-time professional peer, Animesh has made seminal contributions to the PM industry in powder injection molding technology, refractory metals, carbides, and hardmetals. A major collaborative project in the United Kingdom under the title “Engineering the Green State of Powder Products” has provided knowledge and insight into the net-shape forming of powder compacts by die pressing. David Whittaker’s article highlights important outcomes from the program involving six academic research groups and more than 20 industrial partners. Two articles in this issue of the Journal by Vlachos and Chang give insight into the program module on the formulation and mixing of constituent powders in relation to chemical homogeneity and agglomeration.

Alan Lawley Editor-in-Chief

Attention to global economic woes focuses primarily on financial institutions, housing, and manufacturing. In this climate, it is not surprising that projections on R&D support are less than encouraging. According to the Battelle Memorial Institute’s annual report, U.S. inflation-adjusted investment in R&D is set to fall in 2009 after a decade of uninterrupted growth, as corporations and the federal government move into a belt-tightening mode. The drop is expected to be ~1.6% in the U.S., while global R&D spending in inflation-adjusted dollars is expected to be flat in 2009. At best, the PM industry is likely to mirror these projections.

2

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

PM INDUSTRY NEWS IN REVIEW The following items have appeared in PM Newsbytes since the previous issue of the Journal. To read a fuller treatment of any of these items, go to www.apmiinternational.org, login to the “Members Only” section, and click on “Expanded Stories from PM Newsbytes.”

Hopeful Signs in New Transmissions New transmission types offering improved fuel savings are receiving a lot of attention among automotive powertrain engineers, reports Automotive News. They include sixspeed transmissions, manuals, continuously variable, and dualclutch designs. Tungsten Bucking Price Trend Tungsten raw material prices in the U.S. have thus far remained steady but may soon be in freefall, reports American Metals Market. The reason, according to metal dealers and traders, is that demand has disappeared. Outlook Darkens GKN plc, London, UK, issued a statement about deteriorating market conditions, primarily based on new reductions from automotive customers in the last two months of the year. GKN’s global production schedules in November and December are 20 percent lower than forecast in October. Aerospace Industry Relies on Porous Metal Products Mott Corporation, Farmington, Conn., supplies porous metal products that meet stringent aerospace requirements, including the filtration for the onboard air monitoring system in the International Space Station. Important aerospace applications cover flow

4

restriction and surge protection, filtration to prevent clogging of downstream instrumentation, and pressure stabilizers and vents for sensitive environments. Hoeganaes Ending Powder Production in New Jersey Hoeganaes Corporation announced that it will close the last remaining powder production operations in Cinnaminson, New Jersey, during February 2009. The company will continue making ferrous powders at other plants in Tennessee, Pennsylvania, Germany, and Romania. Tantalum Mining Operation Suspended H.C. Starck, Goslar, Germany, announced its regrets about the decision of Talison Minerals Pty. Ltd. to halt mining at the world’s largest tantalum operation in Wodgina, Australia. The miner’s decision is based on the downturn in worldwide demand for consumer electronics, a major user of tantalum products, Starck reports. Solder Powder Business Growing in China Atomising Systems Limited, Sheffield, England, has sold a centrifugal solder powder atomizer to HuaYuan Technologies, Huizhou City, China. The unit produces lead-free tin–silver–copper powders for electronic solder pastes.

PM Sales and Earnings Rise Mask Uncertain Future Miba AG, Laarkirchen, Austria, a supplier to the international automotive industry, posted a four percent rise in sales to 298 million euros (about $405 million) for the first three quarters of its 2008 fiscal year. Earnings before interest and taxes increased from 18 million euros (about $24 million) to 32.4 million euros (about $44 million). Joint Ventures Completed North American Tungsten Corp. Ltd. (NTC), Vancouver, B.C., Canada, has finalized agreements with Tundra Particle Technologies LLC, White Bear Lake, Minn., and its sister company Tundra Composites (TC) to produce and sell commercial tungsten products made from tungsten concentrate. In addition, NTC has received a license for TC’s patented tungsten composites manufacturing process. Press Maker to Restructure ReConditioning, Manufacturing and Marketing Cincinnati Incorporated will combine its satellite facility for re-conditioning metal powder compacting presses into its 500,000 sq. ft. main manufacturing plant in Harrison, Ohio. The transition, scheduled for completion by March 31, 2009, will also include restructuring the company’s powder metal marketing and service groups. ijpm Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

PM INDUSTRY NEWS IN REVIEW

Capstan Adds PM Parts Operation Capstan Inc., Carson, Calif., has acquired the assets of the MPP–Anaheim div. of Metal Powder Products Company (MPP), report Capstan partners Mark Paullin and Chris Doughty. Operating plants in California, Massachusetts, Tennessee, and Jalisco, Mexico, Capstan is the largest individually owned PM parts company in North America. Metaldyne Reduces Costs Metaldyne Corporation, an Asahi Tec company, Plymouth, Mich., has announced actions to reduce structural costs, balance capacity with OEM vehicle production cuts, and focus on core products. The company has reduced headquarters staff, eliminated a leased facility housing its North American Chassis Products business unit, and is consolidating headquarters in one building.

Jet Sieve and Tolling Available Minox-Elcan, Mamaroneck, N.Y., offers the MLS 200 Jet Sieve for small volumes and testing dry materials from 20 to 1,000 microns. Operating with standard 8-inch sieves, the unit prevents inaccurate results due to screen blinding and dedusts statically bound fines, the company reports. PM Equipment Auction The assets of PM parts maker Falcon Diversified Manufacturing Inc. (FDM), Battle Creek, Mich., will be sold at public auction on January 28. The company was formed in 2006 by Ron Holcomb who purchased the assets of Paradigm Sintered Products while in Chapter 11 bankruptcy. ijpm

PURCHASER & PROCESSOR

Powder Metal Scrap (800) 313-9672 Since 1946

Ferrous & Non-Ferrous Metals Green, Sintered, Floor Sweeps, Furnace & Maintenance Scrap

1403 Fourth St. • Kalamazoo, MI 49048 • Tel: 269-342-0183 • Fax: 269-342-0185 Robert Lando E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

5

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

SPOTLIGHT ON ...

ZACHARY Z. ZEBROVIOUS, PMT Education: BS, Industrial & Systems Engineering, Virginia Institute of Technology, 2001 MBA, University of Wisconsin–Whitewater, 2008 Why did you study powder metallurgy/particulate materials? The family tool & die business, Compacting Tooling, Inc. (CTI), is probably what started my interest in powder metallurgy (PM). After spending many of my early years working my way through the shop, moving on to working for a PM parts producer seemed like a natural progression. It was also a move towards a position that was more closely aligned with my undergraduate degree. When did your interest in engineering/ science begin? I do not recall that I had a solid interest in engineering per se until I started working in the family business. As a kid, I had a variety of different interests. I loved to build and paint scalemodel cars and airplanes, yet at the same time I also enjoyed playing a variety of sports. I was also a voracious reader at an early age. So it was hard for me to make a decision. My 8th grade yearbook listed law, medicine, and engineering as future possibilities. But once I got a chance to “get my hands dirty” and create something out of metal, while getting paid, I was hooked. What was your first job in PM? What did you do? My first job was as a janitor during high school at CTI…seriously. I pushed a broom, mopped floors, cleaned the chips out of the mills and lathes, and scraped grit off grinding tables. During the Christmas break of my freshman year in high school, I learned how to strip down the reservoir tank on an Eltee EDM machine so that I could clean out about 5 years’ worth of sludge and grime. For those who want to try it, wear elbow-length gloves…the black sludge stains the skin! I think it took a week to sweat it out. After that experi-

6

ence, I spent just about every summer and break working in the shop. I started working full-time immediately after I graduated from VT. Describe your career path, companies worked for, and responsibilities. My career path is short as I have only worked for two companies in my lifetime. I managed to work my way through the various areas of tool & die manufacturing: heat treatment, turning, milling, jig/NC grinding, OD grinding, surface grinding, finishing/lapping, inspection & CAD/CAM. After graduating from college, I moved directly into production management. I took over many of the day-to-day operations (with the help of a great team) while my father concentrated on quoting and maintaining open lines of communication with our customers. In 2004, my parents decided to retire after 34 years in the business and I made the personal decision to move on. A team of our former employees purchased the company, and I came to SSI as a process engineer. My career at SSI has kept me primarily in the fully dense and structural components business units (BUs). After completing my introductory period, I moved into the fully dense BU as their process engineer. I like to think that my experience in this department helped me to develop a solid foundation in PM concepts. With much larger shrink factors (around 7% on average), learning the nuances of density control and powder flow were important. I also received a solid introduction to the basics of metallurgy and an understanding of microstructures. With time and experience, SSI moved me into a product/process role within their structural components BU. To date, this has been a Process Engineer SSI Technologies, Inc. 3330 Palmer Drive Janesville, Wisconsin 53546 Phone: 608-373-2843 E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

SPOTLIGHT ON ...ZACHARY Z. ZEBROVIOUS, PMT

perfect fit as I have been given a chance to work with low- and high-temperature sintering, multilevel pressing, secondary machining operations, and some automation projects. Also, I have been able to work with a much wider spectrum of customers. Some are automotive-oriented while others are not. And I have gained the ability to work with both foreign and domestic customers and suppliers. I truly appreciate the variety of opportunities that my current position offers. What gives you the most satisfaction in your career? I enjoy the challenge of fabricating “problem” parts and the variety of issues that my position offers. I enjoy speaking with customers and learning about how our components are integrated into their systems. Most of all, I enjoy succeeding in developing a PM part or resolving an issue with one of my components. If I did not deal with “challenges” on a daily basis I do not think that I would be in the same field. Despite the constant challenges posed by the domestic automotive

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

industry and global competition, I find that I have enjoyed my career path thus far. List your MPIF/APMI activities. I have been somewhat lax in attending APMI International events. The Chicago Chapter does not hold a large number of meetings, so I have tried to attend those that did not interfere with my graduate school schedule. The same holds for many of the seminars that are held throughout the year. Going back to school at night has really cut back on the amount of free time in my schedule. Hopefully, I will have opportunities in the coming years to become more involved. I do enjoy reading the International Journal of Powder Metallurgy. What major changes/trend(s) in the PM industry have you seen? I have not been involved in the PM industry long enough to witness significant changes. The major trends that I have seen have involved a move towards leaner production systems with shorter lead times, increasing pressure from customers to

7

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

SPOTLIGHT ON ...ZACHARY Z. ZEBROVIOUS, PMT

reduce prices, and an ever-increasing focus on product quality and tighter tolerances. This progression seems natural as economies continue to open up globally. The trend that I am not excited about, however, is the reluctance of young people in the U.S. to consider manufacturing as a viable and rewarding career path. From my limited experience, finding and retaining talented staff with both a mechanical aptitude and a strong work ethic has become increasingly difficult to manage. In my opinion, being able to figure out the solution to this problem is what will help define and drive domestic manufacturing in the future. Why did you choose to pursue PMT certification? SSI was the primary driver behind my obtaining PMT certification, since becoming certified was one of my goals. Obtaining certification was an excellent way to lear n about PM in a short amount of time. SSI had a group of us take the ASM International PM course which did an excellent job of explaining all of the nuances involved in the technology, from powder processing to molding to the various forms of sintering. It was also an excellent crash course for the PMT certification examination. Having certification has given me confidence that I am proficient in the core areas of PM technology. Working to obtain certification has also given me the background informa-

8

tion that is essential to being a competent engineer within the PM industry. How have you benefited from PMT certification in your career? The knowledge I obtained while studying for the certification examination has been useful on a daily basis. In addition to using statistics and mathematics regularly, my job requires that I understand how powder particles flow, how they are compacted, how they react when heated, and how PM materials can be effectively machined. Certification has helped to build my knowledge base of PM principles. What are your current interests, hobbies, and activities outside of work? I have far too many hobbies and participate in far too many activities for my own good! I recently adopted my first greyhound, Titan, and am hoping to have him attempt some lure coursing events next summer. I spend time in the gymnasium weight lifting, and I enjoy running and biking. I am a tinkerer, so at any given time I usually have two or three projects going on in my house. My move to Wisconsin also introduced me to sportbikes. I found that I have an addiction to twisty roadracing tracks and the sound of an engine at 10,000 RPM! ijpm

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

DAVID WHITTAKER* Q A

How do you rate the prospects for future growth of titanium PM applications? It is tempting to simplify this answer by saying that a reduced titanium powder price is the key to such prospects. However, it is not as straightforward as that; it depends on the particular user sector and application in mind. So, let us consider a number of different potential user sectors. The automotive and general engineering sectors certainly have an active interest in the benefits that titanium alloys could offer, including high specific strength, a density ~45% less than that of steel, and corrosion resistance about four times better than that of stainless steel. With the exception of unique motorsport applications, titanium would generally have to replace the ferrous materials currently used in the target applications. In this type of application, therefore, the cost of the starting material will be absolutely paramount in determining potential cost competitiveness. Even on a cost/specific-strength basis, titanium is currently 25 times more expensive than steel! There has been considerable development activity in such applications back in the 1980s, particularly in North America. I recollect at least one SAE paper on the subject, which referred to applications that, from memory, included valve spring retainer caps and the ubiquitous connecting rod. This development activity was in part stimulated by the existence at the time of a source of a potentially low-cost titanium powder feedstock—titanium sponge fines, the by-product from a Hunter process extraction plant. When this source disappeared, so did the prospects of these developments translating into production applications. To reactivate interest in such applications, lowercost powders would certainly be required. The current costs of commercial titanium or titanium alloy powders span the range from >$320/kg for the highest grade plasma-spray-atomized powders, through

$200–$260/kg for plasma rotating electrode (PREP) and gas-atomized grades, and $65–$200/kg for titanium hydride/dehydride (Ti-HDH) grades. Although there has been reported development activity that uses Ti-HDH powder mixed with elemental or master-alloy additions as feedstock, this type of application is really waiting for one of the many emerging powder-production processes, promoted as being potentially low cost, to deliver on their potential. There was a time when one of these emerging processes, a UK invention, the FFC Cambridge electrolytic de-oxidation process, looked to be the frontrunner. This process involved electrolysis in a molten salt electrolyte to strip oxygen ions away from a cathode, made by pressing low-cost TiO2 powder, to leave titanium. At the development stage, this process promised significant energy-efficiency benefits compared with the Kroll process for titanium sponge and, as a direct powder -production process, large cost-reduction benefits. However, the process has subsequently run into scale-up problems. Achievable electrolysis rates have proven to be severely limited by the need to reduce residual oxygen content sufficiently, and to avoid unwanted reactions between the cathode and electrolyte materials that produce compounds rather than the pure metal. Also, “wasted” background current (associated with electron conduction through the electrolyte) has meant that the achievable energy efficiency to date has only beaten that of the Kroll process by a factor of about two, rather than the factor of six or seven originally envisaged. The emerging U.S. process that must be rated as being closest to commercial reality is the Armstrong process developed by International T itanium

*Consultant, David Whittaker & Associates, 231 Coalway Road, Merryhill, Wolverhampton WV3 7NG, UK; Phone: 44 1902 338498; E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

9

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

Powder, L.L.C., which relies on the reduction of TiCl4 with molten sodium. There is a now a strong development focus on the application of this powder type. Now, let us turn to other user sectors, where issues other than the material cost are dominant (although, of course, even these sectors would welcome the availability of lower-cost powders as long as they satisfy attendant quality requirements). In the aerospace sector, both airplane engine and airframe manufacturers are expressing an interest in PM titanium-alloy components. The driving force here is the need for cost reductions in components that are already specified as titanium-alloy products and are currently machined from wrought titaniumalloy feedstock. Such components currently exhibit low material- utilization rates, with “fly-to-buy” ratios often being <10%. As the cost of the wrought feedstock is of the order of $40/kg and at least 90% of it is wasted, it is possible to argue that a PM route with high material utilization could tolerate even the highest level of powder price quoted earlier, and still derive a material-cost advantage. This would be further enhanced by PM’s net-shape capability, given that, in conventional manufacture, the machining of titanium is difficult and expensive. Such applications would, of course, be high integrity and safety critical and PM process routes would therefore generally involve hot isostatic pressing (HIP) to achieve full density. In addition, there would be stringent quality requirements on the starting powder materials, particularly in terms of the allowable contents of oxygen, carbon, and other interstitials. Medical implants is a market in which wroughtroute Ti-6Al-4V already competes and PM titanium routes can potentially offer a number of advantages. One major attraction of PM would be the ability to directly create porous surface structures to aid bone integration after the implantation. A number of developments have been presented at recent PM conferences that involve the use of “space holder” additions to the PM feedstock that can be removed after the forming of the component to create such a structure. The forming processes investigated have included both metal injection molding (MIM) and conventional press-and-sinter PM. A further process route of interest in this context is the possible use of selective laser, or electron beam, melting free-form fabrication. Apart from offering a means of building the required porous structures, there would now be the possibility of tailor-making “one-off” products for individual patients starting from the results of CT scans.

10

With specific reference to MIM, there is already some market penetration for titanium parts in the medical, aerospace, and consumer goods sectors. Because MIM parts are generally small and light, the starting material cost is not such a dominant issue as for, say, conventional PM parts. Reports from a specialist company that is extending this penetration into the medical-implants field indicate that, again, the need for extra-low interstitial powders is emerging and that special binders and sinteringatmosphere control are also required to avoid interstitial pick-up during the MIM process route. Finally, there are PM titanium opportunities in the jewelry sector. This sector might seem an odd one to cite as it is never going to consume large tonnages of powder and therefore might not get the powder suppliers too excited. Its sales value may, however, be significant enough to interest potential processors of PM products. I have information available only for the UK jewelry sector, but this indicates that its annual value is of the order of $5 billion and profitability is high. There are a number of reasons driving the growing interest in titanium jewelry: the popularity of body piercing requiring hypoallergenic materials; the design trend towards simpler white metal designs; and the public perception of titanium as a “high-tech” material. In this sector, there is some limited MIM penetration and this could potentially be expanded. Also, free-form fabrication techniques could lend themselves to some of the small-batch needs of this sector; the use of such technologies, at least for prototyping, is well known in the industry. It is likely that powder-compositional quality requirements may well be less stringent in this sector.

Q

Does the PM industry give sufficient guidance and information to end-user designers on fatigue performance of its materials to stimulate the development of high-performance press-and-sinter structural parts? Those of you who know me would certainly expect me to highlight the Global PM Property Database (GPMPD) in responding to this question. So, I shall not disappoint you! The GPMPD has now been available since 2004 and the development of its current content has been largely the responsibility of the writer (on behalf of EPMA), and Howard Sanderow (on behalf of MPIF), with significant support from members of our individual Accreditation Committees and our counterparts at JPMA.

A

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

CONSULTANTS’ CORNER

Prior to its existence, sources of available fatigue data for PM materials were, at best, fragmented and the GPMPD has been useful in providing a unified source of what is available in this context. The GPMPD has been correctly recognized as a powerful tool but, in terms of fatigue properties, it would be unreasonable to suggest that the current content is anything other than a promising start in addressing what ideally is needed. What is there at the moment gives a reasonable collation of the available fatigue-endurance-limit data and considerable care has been taken to ensure that only data of reliable quality have been included. The information collated does cover a number of different fatigue loading modes (axial, plane bending, and rotating bending) and, for materials where fatigue data could be found, a range of density levels and, where relevant, the influence of post-sintering heat treatments. However, this endurance-limit information is exclusively derived from load-controlled S-N testing and is dominated by test results in fully reversed loading (R = -1) and with unnotched test-pieces (Kt = 1). Also, full fatiguecurve information, including the low-cycle portion of the curve and individual test result points, is not currently accessible to the searcher. Supporting information in the database structure does deliver the message to design engineers that the sensitivity to external notches (i.e., values of Kt other than 1) and the rules for correcting for mean stress levels other than zero (i.e., values of R other than -1) are different for press-and-sinter PM materials from those for fully dense wrought steels, with which they are more familiar. Also, the database does provide guidance documents on these issues. However, it is relatively easy for the searcher to miss the existence of this supporting information. Although the information on endurance limit readily accessible to the searcher is useful in giving a means of comparing PM materials with currently specified materials for fatigue-dependent applications, this leaves the PM industry with a long-standing problem. Namely, this approach to material selection will always underrate the actual capabilities of PM materials in real-life component applications, which always contain external stress raisers in their geometries. For instance, it ignores the welldocumented lower notch sensitivity of porous PM materials compared with wrought steels. Both MPIF and EPMA are striving to address these current limitations and have been directing their efforts in different but hopefully complementaVolume 45, Issue 1, 2009 International Journal of Powder Metallurgy

ry areas. MPIF is seeking to address a perceived need for fatigue data for PM materials derived under straincontrolled testing regimes. Such data would be relevant in automotive chassis and steering applications, for example. On the basis that the primary PM targets in more highly stressed applications (e.g., automotive engines and transmissions) are not seen as likely to experience macroscopic plasticity in service, EPMA has decided to focus on attempting to enhance the information and guidance available to designers, who are content to rely on load-controlled S-N data in their design methodologies for such applications. Ideally, such a designer needs to be able to define: • The fatigue loading mode in the target application • The mean stress level or R ratio • The external notch factor, Kt, in the critical area of the design The designer then needs to have access to full S-N data for any material(s)/density level(s)/heat treatment conditions that satisfy the fatigue-performance requirements under the specified conditions. With the assistance of Professor Paul Beiss and his group at the Technical University, Aachen, Germany, EPMA is using its own funding to pursue a program with an initial focus on the Fe-Cu-C family of materials, on the basis that they constitute at least half of the current PM structural-part market and their fatigue properties have already received significant attention in published research. As a first step to providing the capability cited here, all available published information has been collated and presented in a standard S-N curve and tabular format—a not inconsiderable body of data, comprising at least 130 datasets. The next step will be to develop a means of providing access to these curves and tables within a searchable format within the GPMPD, as the major vehicle for delivery of this information. In further phases of this work, it is anticipated that defined gaps in the Fe-Cu-C information will be filled through the derivation of new data. Similar exercises will then be pursued for other PM grades, deemed to be of significant potential interest for fatigue-dependent applications. ijpm

Readers are invited to send in questions for future issues. Submit your questions to: Consultants’ Corner, APMI International, 105 College Road East, Princeton, NJ 08540-6692; Fax (609) 987-8523; E-mail: [email protected]

11

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 International Conference on Powder Metallurgy & Particulate Materials June 28–July 1, The Mirage Hotel, Las Vegas

• International Technical Program • Worldwide Trade Exhibition • Special Events

For complete program and registration information contact: INTERNATIONAL

METAL POWDER INDUSTRIES FEDERATION APMI INTERNATIONAL 105 College Road East Princeton, New Jersey 08540 USA Tel: 609-452-7700 Fax: 609-987-8523 www.mpif.org

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ENGINEERING & TECHNOLOGY

ENGINEERING THE GREEN STATE OF POWDER PRODUCTS David Whittaker*

INTRODUCTION Two papers, published in this issue of the Journal, have been drawn from work at the University of Birmingham, UK, which comprised one module within the collaborative project. My purpose here is to “set the scene” for the two UK contributions by placing them within the context of the wider project. This project and the collaborating consortium were developed under the aegis of the UK networking organization PowdermatriX. PowdermatriX was initially established as a Faraday Partnership in late 2002 and, since the beginning of 2006, has been part of the UK Materials Knowledge Transfer Network. It promotes innovation and technology transfer in advanced ceramics, powder metals, hardmetals, magnetic materials, and pharmaceutical powders and helps its members by signposting them to the best technical advice available, and by developing new collaborations and projects. “Engineering the Green State of Powder Products” has been a major project of PowdermatriX and the Engineering and Physical Sciences Research Council (EPRSC), providing new knowledge and insight into net-shape forming of powder compacts by die pressing. On its launch, PowdermatriX was designated £1 million by the EPSRC to develop university-based research projects with significant industry support. The project was the single largest project developed at this time, involving six academic research groups and over 20 companies spanning all of the target powder-forming sectors. The program has delivered fundamental understanding for improved process control of each step involved in the production of green (unsintered) compacts by die pressing—the dominant powder-forming route in the many industry sectors within the PowdermatriX community. Metal, hardmetal, ceramic, and magnetic components, and pharmaceutical tablets are all examples of products manufactured using closed-die compaction of powders. As formation of a high-quality green body is the key to obtaining acceptable final product properties, research concentrated on each of the production stages. A typical processing route for a multilevel part manufactured from powder by die pressing involves: • initial formulation and mixing of constituent powders, • handling and transport of the powder mix to the press and its delivery to the fill shoe,

This paper highlights the important outcomes from a major collaborative project in the UK, under the title “Engineering the Green State of Powder Products.” The project has provided new knowledge and insight into the net-shape forming of powder compacts by die pressing. It has involved the collaboration of six academic research groups and over 20 industrial partners, spanning the powder metal, advanced ceramics, hardmetals, magnetic materials, and pharmaceutical tabletting sectors. Through a combination of novel experimental observations and, where appropriate, numerical simulation, the project has studied all the process stages involved in the production of green (unsintered) compacts.

*231 Coalway Road, Merryhill, Wolverhampton WV3 7NG United Kingdom; E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

13

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ENGINEERING THE GREEN STATE OF POWDER PRODUCTS

• • • •

filling of the die cavity from the shoe, pre-compaction powder transfer, compaction, and ejection of the compact from the die.

FORMULATION AND MIXING The University of Birmingham adopted a twintrack approach: 1. Development of a formulation strategy to achieve an optimum combination of apparent density and flow characteristics 2. Development of mixing process maps to allow the selection of mixing conditions (blender fill ratio, mixing time, and speed) to achieve minimum levels of chemical segregation in the powder mix (maximum “degree of mixedness) In developing the formulation strategy, commercial aluminum, copper, and iron powders were studied. The starting powders were separated into sieve fractions, which were then remixed in a range of ratios and the properties of the mixes assessed. Optimum ratios of sieved fractions were defined. Neural network modeling, based on a Gaussian process, was then applied to predict properties for given starting materials. A good correlation was seen between predictions and observed results. The mixing work was based on two case studies: one involving iron–ferrosilicon mixes and the other iron–nickel mixes1 with two different average nickel-particle sizes (8 µm and 1.5 µm). The constituent powders were mixed in a laboratory scale (1 L capacity) double-cone mixer/blender. The influence of mixing conditions was studied using Taguchi statistics and analysis of variance (ANOVA) methods. The “degree of mixedness” was then quantified using a novel experimental technique, which involved resin impregnation to “capture” the condition of chemical segregation within a powder mix immediately after the mixing process. 1,2 After curing the resin, the powder mass was sectioned and analyzed using backscattered scanning electron micrograph (SEM) images. Mixing-process maps were created using the standard deviation in compositional level of the alloying element (nickel or silicon) from the multiple analyses of the individual sections at the particular combination of processing conditions as an inverse measure of degree of mixedness. The process map, for the mixing of -100 mesh (<150 µm) iron powder with the 1.5 µm nickel

14

Figure 1. Evidence of de-mixing at a combination of high mixing speeds and long mixing times, in mixing of iron powder (<150 µm) and 1.5 µm nickel powder with a low blender-fill ratio (35%)

powder with a low mixing-fill ratio of 35 v/o, demonstrated clear evidence of a propensity for de-mixing with a combination of longer blending times and higher blending speeds, Figure 1. The numbers on the “contour lines” of this plot are the standard deviations of the compositional frequency plots for the section samples analyzed at the particular combinations of mixing conditions. This parameter is used as an inverse measure of “degree of mixedness”. The possibility of de-mixing, if mixing is carried on for too long, is part of the industry’s folklore. The work reported is believed to be the first direct experimental observation of this phenomenon. The issue of scaling up the process mapping work from the laboratory to industrial-scale blenders is currently being addressed in collaboration with industrial partners within the project consortium. Here, the validity of scaling factors, already published in the literature, will be tested. POWDER HANDLING AND DELIVERY TO THE PRESS The University of Greenwich has studied issues that can affect the flow characteristics and chemical segregation of a powder mix once the mixing process has been completed, i.e., powder handling and transport to deliver powder into the fill shoe on the compaction press. This work has been Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ENGINEERING THE GREEN STATE OF POWDER PRODUCTS

Figure 2. Sintered-part weight variation through a powder batch caused by air-induced segregation of the wax lubricant addition

built around a number of industrial case studies, the first of which (on soft magnetic materials) included in-plant sampling and the development of a sampling device immediately above the fill shoe on a production press. Many useful guidelines on sampling procedures and the selection and conducting of test procedures for particle-size distribution, apparent and tap density, segregation, 3 and flow characteristics4 have been generated. The design of feed hoppers to promote mass flow rather than core flow has also been considered. In the case studies, the dominant segregation mechanism was found to be air-induced segregation of lighter constituents in the delivery tube from feed hopper to the press fill shoe. In one instance, this effect caused the wax (lubricant) content to rise throughout a powder batch run, this proving to be the major contributor to sintered part weight variation, Figure 2. In another case, air-induced segregation was observed to create a variation in the content of the active ingredients by >30% on a batch run of a pharmaceutical mix.5 DIE FILLING Studies at the University of Leicester have used a combination of experimental visualization of diefilling processes, by means of transparent Perspex® toolsets and fill shoes, high-speed video photography,6,7 and numerical simulation. The concept of the critical shoe velocity for complete die fill has been used as a measure of powder flow during the process. Previous work on powder flow in gravity die filling has been extended to assess the influence on die fill of the reversal of air flow out of the die cavity through the use of downward suction effects Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Figure 3. Benefit of suction filling on die fill rates for Distaloy AE powder

past the lower punch, Figure 3.8 The influence of fluidization in the fill shoe has also been studied. Professor Alan Cocks, the joint supervisor of this work, now at Oxford University, is following a new direction for the numerical simulation of powder flow ef fects during die filling. The approach will consider powder flow in terms of soil mechanics, where the pore fluid is air. This is a novel approach, which could have a fundamental bearing on the understanding of powder flow. PRE-COMPACTION POWDER TRANSFER Powder flow during pre-compaction powder transfer in the die has been the subject of several collaborative studies involving the University of Leicester and the University of Manchester. Studies have tracked powder flow around various types of punch in an Al-10 w/o Sn mix using novel X-ray tomography and image correlation techniques; the tin addition provides markers to follow the flow.9 In one such study, the results have been correlated with the predictions of discrete element modeling (DEM), Figure 4. In Figure 4 (b), red and blue denote maximum distances of powder movement in the downward and upward directions, respectively. The intermediate colors denote lower levels of powder movement, or in some cases the total absence of powder movement. In more recent studies, the same techniques have been used to follow the flow of coarser (200 µm) iron powder. The individual particles can be resolved during X-ray tomography and therefore act as their own markers. One study has allowed the derivation of powder displacement maps that identify the formation of a “deadwater” shear zone associated with flow around a lower punch, Figure 5. The color coding denotes the total amounts of downward displacement of powder

15

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ENGINEERING THE GREEN STATE OF POWDER PRODUCTS

Figure 4. Powder movements during pre-compaction powder transfer: (a) predicted by DEM and (b) observed by X-ray tomography and image correlation Figure 6. Verification of the presence of a “deadwater” shear crack above the face of a lower punch (cf. powder movement tracked in Figure 5)

shape, individual particles were tracked. These studies have provided input for numerical modeling of early-stage compaction at the University of Aberdeen.

Figure 5. Observation of a “deadwater” shear zone during the downward movement of powder around the face of a lower punch, using X-ray tomography and image correlation

during the compaction experiment, for each element of the final compact volume. Subsequent metallography confirmed the capacity for the formation of a “deadwater” shear crack in this region, Figure 6. Also, other areas of high shear movement have been observed, which could potentially lead to cracking. EARLY-STAGE (LOW-PRESSURE) COMPACTION The particle rearrangements involved in earlystage (low-pressure) compaction have also been studied at the University of Manchester Institute of Science and Technology with X-ray tomography. Again using coarser (200 µm) iron powder grades of both spherical and irregular particle

16

COMPACTION AND EJECTION The University of Aberdeen has developed a user-defined material model (UMAT) that is compatible with Abaqus and incorporates deformation by particle rearrangement and damage to particles. This model10 has been used to predict: • Particle rearrangements in early stage compaction • Development of tensile stresses during ejection • Formation of shear bands through the onset of shear localization Development of the tensile stresses during ejection, based on a linear elastic analysis of a compact half ejected from the die (i.e., the upper half

Figure 7. Development of tensile stresses during compact ejection

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ENGINEERING THE GREEN STATE OF POWDER PRODUCTS

of the compact is clear of the die while the lower half is still contained within the die cavity) is illustrated in Figure 7. The indicated stress levels in the compact are in Pa. CONCLUDING REMARKS This paper provides only a brief flavor of the outcomes from this major project. Much greater detail has been provided in a series of presentations at an Industrial Workshop at the conclusion of the project. For anyone wanting to explore this in greater detail, copies of the delegate packs from the workshop (containing a CD of the day’s presentations, summary reports, and published papers from each of the academic groups) can be obtained from PowdermatriX, or by contacting the author at [email protected]. ACKOWLEDGMENT This paper is based on the content of a contribution made to the Euro PM2008 Conference, held in Mannheim, Germany, and organized by the European Powder Metallurgy Association (EPMA). The permission of EPMA to use the content in this paper is gratefully acknowledged.

3.

4.

5.

6.

7.

8.

REFERENCES 1. N. Vlachos and I.T.H. Chang, “Investigation of the Distribution and Agglomeration of Extra Fine Nickel (T110) in Blended Iron-Nickel Powder Mixtures”, Advances in Powder Metallurgy & Particulate Materials— 2008, compiled by R. Lawcock, A. Lawley and P. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, part 2, pp. 85–96. 2. N. Vlachos and I.T.H. Chang, “The Study of Chemical Segregation by Image Analysis and X-ray Mapping”, Proc.

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

9.

10.

International Conference on Particle Technology (PARTEC), organized by The Institute of Particle Technology, University of Erlangen-Nuremburg, Erlangen, Germany, 2007. P.A. Kulkar ni, M.S.A. Bradley and R.J. Far nish, “Predicting Segregation of Metal Powders”, Powder Metallurgy, 2006, vol. 49, no.3, pp. 206–208. P.A. Kulkarni, M.S.A. Bradley and R.J. Berry, “Flowability Measuring Techniques— Sensitivity to Change in Composition”, CHoPS 2006 (Conveying and Handling of Particulate Solids), 5th International Conference, Ortra Limited, Tel Aviv, Israel, 2006, chapter 4. P.A. Kulkarni, R.J. Furnish, M.S.A. Bradley and A.R. Reed, “Evaluation of Air Induced Segregation Tendencies in Pharmaceutical Blends Using a Bench Scale Tester”, ICBMH, 9th International Conference on Bulk Materials Handling, University of Newcastle, Australia; edited by M. Jones, published by Engineers Australia, Barton ACT, Australia, 2007. L.C.R. Schneider, I.C. Sinka and A.C.F. Cocks, “Characterisation of Pharmaceutical Powders Using a Model Die-Shoe Filling System”, Powder Technology, 2007, vol. 173, no.1, pp. 59–71. L.C.R. Schneider, A.C.F. Cocks and A. Apostolopoulos, “Comparison of Filling Behaviour of Metallic, Ceramic, Hardmetal and Magnetic Powders”, Powder Metallurgy, 2005, vol. 48, no. 1, pp. 77–84. F. Motazedian, A.C.F. Cocks and I.C. Sinka, “The Influence of Airflow in Gravity and Suction Filling”, Advances in Powder Metallurgy & Particulate Materials— 2007, compiled by J. Engquist and T.F. Murphy, Metal Powder Industries Federation, Princeton, NJ, 2007, vol. 1, part 3, pp.1–9. S.A. McDonald, L.C.R. Schneider, A.C.F. Cocks and P.J. Withers, “Particle Movement During the Deep Penetration of a Granular Material Studied by X-ray Microtomography”, Scripta Mater., 2006, vol. 54, pp. 191–196 H.W. Chandler and C.M. Sands, “The Role of a Realistic Volume Constraint in Modelling a Two Dimensional Granular Assembly”, J. Mech. Physics of Solids, 2007, vol. 55, pp.1,341–1,356. ijpm

17

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

RESEARCH & DEVELOPMENT

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION Nikolaos Vlachos* and Isaac T.H. Chang**

INTRODUCTION Efficient mixing and sampling of powders are of critical importance in the manufacture of many products, including PM parts, pharmaceuticals, ceramics, catalysts, glass, cement, and magnetic media. The raw particulate materials for conventional PM parts usually consist of a mixture of elemental, master alloys and lubricant powders in various proportions. Hence, the preparation of powder mixtures is essential in order to obtain the required alloy compositions at relatively low cost and with acceptable compressibility. Consequently, the mixing of powders plays a major role in the quality and consistency of the resultant parts.1 Design and optimization of powder mixing operations require accurate analytical methods to determine the quality of the mixture. The most common approach employed in the PM industry to characterize a mixture is the use of a thief probe to withdraw samples from different locations in stationary powder mixtures. The use of the thief probe can frequently introduce two types of errors. Firstly, the mixture is extensively disturbed when the thief probe is inserted into the powder bed, dragging particles along the path of insertion of the probe. The sample that is collected is likely to contain particles from all positions along the path.2–4 Secondly, particles of different sizes often flow unevenly into the thief cavities.2–5 Another common method is the colorimetric technique, which consists of mixing coarse particles with pigments. The main disadvantages are that it gives information only at the walls and is not applicable to industrial powders.1,5,6 In order to perform out a dynamic analysis of the interior of a granular bed, different techniques have been used, such as positron emission particle tracking (PEPT) in which a single radioactive particle is tracked during flow within a granular bed using an array of external photomultipliers, and magnetic resonance imaging (MRI), where magnetic moments of hydrogenated particles are aligned in structured configurations and these structures are tracked for a short period. Such techniques, however, are complex and expensive to set up and can

Homogeneity and agglomeration in powder mixes are major issues in the powder metallurgy (PM) industry, and need to be optimized to fabricate near-net-shape parts of complex geometry to tight tolerances. We describe a new method, a “freezing” technique, for obtaining quantitative characterization of industrial metal powder mixtures, which has been developed with the aim of holding powders in place with minimal disruption of powder position. The effect of the mixing parameters (filling ratio, rotation speed, and mixing time) on the uniformity of the mixture and the size/population agglomerations, based on an Fe-6 w/o ferrosilicon powder mixture, are assessed. Mixing homogeneity and agglomeration are quantified in terms of the standard deviation of the volume ratio of ferrosilicon: iron and the average number of particles for each aggregate in each mixing condition, respectively. For an asymmetrical double cone mixer/blender, mixing speed and time were found to be the most predominant factors controlling the chemical homogeneity of the mixture. Volume-fill ratio and mixing speed were found to be the most significant factors influencing the aggregate size.

*PhD Research Student, **Senior Lecturer, School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom; E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

19

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

only be used in a dedicated laboratory.7–9 In light of these limitations, a key problem in the PM industry is the lack of suitable techniques for sampling particulate mixtures without disturbing the structure of the mixture. This has resulted in a lack of rigorous quantitative evaluations of the actual powder mixing process. Our method involves a curing or “freezing” technique to preserve the structure of the mixture in an undisturbed state, facilitating subsequent observation. 10 This approach enables a complete assessment of mixing by allowing examination of the composition of the local mixture as a function of position. Another advantage of this method is the direct observation of the structure of the complete mixture: mixing patterns can be viewed both internally and at exposed surfaces.10–12 Mixer/blender types can be divided into two categories: convective mixers/blenders and tumbling mixers/blenders. Convective mixers/ blenders involve the use of a paddle, blade, or screw, which stirs the powder inside an immobile vessel, whereas tumbling mixers/blenders rely upon the action of gravity to cause the powder to cascade within the rotating vessel. Tumbler mixers/blenders can handle free-flowing and cohesive powders but not pastes, and quality is a problem. Free-flowing powders can segregate on the tumbling surface, which frequently increases segregation. Weakly structured powders are broken down within the mixer/blender but small agglomerates or aggregates of an ingredient can remain intact. Although quality will always remain a problem, the tumbler mixer/blender has significant advantages compared with a convective mixer/blender. It can be manufactured in a wide variety of noncontaminating materials, its simple shape enables good access for both cleaning and sampling, and it has no internal bearings contacting the product. A variety of simple shapes, such as cubes, double cones, and V-shapes, are used with rotational speeds of typically 5 to 30 rpm. In recent years, some studies have focused on investigating and improving the homogeneity of powder mixtures in a double-cone mixer/blender. Most of these studies did not use commercial metal powders. They investigated the effect of overall mixture composition on the performance of a double-cone mixer/blender for mixtures of differently sized sand, salt, and glass beads (which are usually free-flowing particulate systems). Recently, studies have focused on the effect of cohesion in

20

dry cohesive mixtures with uniform or non-unifor m particle size in a cylindrical tumbler mixer/blender. However, there is a dearth of scientific literature on the effect of operational parameters in double-cone mixers/blenders on the quality of the mixture (using binary mixtures of metal powders with different particle-size distributions and flow properties). Also, the Taguchi technique to analyze and minimize chemical segregation and agglomeration has not been investigated. The aim of the Taguchi approach is to identify the best product or process characteristics that minimize sensitivity to noises. The Taguchi design can be used to define the effect of mixing conditions on characteristic properties and the optimal combination of conditions. This simple and systematic approach is used to optimize design for per for mance, quality, and cost. 13–15 In the Taguchi approach, orthogonal arrays and analysis of variance (ANOVA) are used. ANOVA can estimate the effect of a factor on the characteristic properties, and experiments can be performed with minimum replication using the orthogonal arrays. Conventional statistical experimental design can determine the optimal conditions on the basis of the measured values of the characteristic properties. The Taguchi method can determine the experimental conditions having the least variability from the optimal condition. The variability is expressed by the signal-tonoise ratio (S:N). The terms “signal” and “noise” represent the desirable and undesirable values for the output characteristic, respectively. The Taguchi method uses the S:N value to measure the quality characteristic deviating from the desired value. The experimental condition having the maximum S:N value is considered as the optimal condition as the variability characteristics are inversely proportional to the S:N.13,15 There are three categories of quality characteristics in the analysis of the S:N, namely, thelower -the-better, the-higher -the-better, and the-nominal-the-better. In this study, the-lowerthe-better quality characteristic was used. The S:N of each level of testing parameters was computed based on the S:N analysis. The-lower-thebetter is usually the chosen S:N for all undesirable characteristics such as “defects,” for which the ideal value is zero. Also, when an ideal value is finite and its maximum or minimum values are defined, the difference between measured data and the ideal value is expected to be as small Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

as possible. The generic form of the S:N then becomes: S:N = -log (1/n)Σyi2

(1)

where yi is the primary response and n is the number of repetitions of each experiment. Here, we describe a new method for obtaining a quantitative characterization of industrial metal powder mixtures. In addition, the study seeks to determine the effect of the mixing factors on the uniformity of the mixture (without chemical segregation) and the size of agglomerations (average number of particles in each agglomerate), using a mixture of ferrosilicon powder and pure iron powder. Previous studies, dealing with mixing of dry cohesive or free-flowing powders, have shown that the homogeneity of the final mixture depends on multiple parameters, such as the initial loading pattern, percentage fill level, mixing time, component concentration, mixer geometry, use of premixing, and its physical properties (such as particle density, shape, size ratio, surface properties, and the intensity of cohesion). The volumefill ratio of the asymmetric double cone mixer, mixing speed (rpm), mixing time (min), and the number of revolutions are key factors in evaluating homogeneity and agglomeration issues in the mixture. The main objective was to use the Taguchi approach to find a combination of effective parameters to achieve mixtures without chemical segregation and agglomeration. METHODS Materials & Mixing Conditions Quantitative experiments were performed using free-flowing pure iron powder and a cohesive ferrosilicon powder (Figure 1) loaded into horizontal layers (Figure 2) in a non-symmetrical double cone, with a volume capacity of 1 L. According to Brone and Mazzio,1 symmetrical top-to-bottom loading introduces stress during radial mixing, and hence increases the mixing rate compared with loading the blender left-to-right, which emphasizes slower axial mixing. The pure iron powder has a mean diameter of 102.5 µm (Coulter wet laser diffraction), and an apparent density of 3.041 g/cm3. The ferrosilicon powder has a mean diameter of 25 µm and an apparent density of 2.081 g/cm 3. The nominal composition of the mixture was Fe-6 w/o ferrosilicon; this is equivalent to a 9,383 v/o ratio of ferrosilicon to iron. Mixing was performed using a Pharmatec Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Multi-blender MB 015, Figure 2(b). Fill levels between 35 v/o and 65 v/o were evaluated. Industrial-scale double-cone mixers/blenders generally run at a constant rotational speed, and a constant rotational speed was used in each of the experiments reported. Speeds between 15 and 30 rpm were utilized in our experiments. This range of speeds was based on a Froude number similarity criterion, the Froude number being between 0.02137 and 0.08548. Currently, there is no generally accepted method for determining the change in operational parameters governing an increase in equipment size. The most commonly recommended method for scaling granular systems involves the use of the Froude number Fr, given by the relation: Fr = Ω2R/g

(2)

where Ω is the rotational speed, R is half the total mixer/blender height perpendicular to the axis of rotation, and g is the acceleration due to gravity. Each experiment was run for a predetermined mixing time, between 10 and 45 min. Subsequently, quantitative data were obtained via image analysis, using a combination of scanning electron microscopy (SEM) and image analysis.

Figure 1. Images of (a) pure iron powder of irregular shape, and (b) ferrosilicon powder (large particles have irregular shape, smaller particles have spherical shape). SEM

Figure 2. (a) Schematic showing powder-filling protocol, (b) multi-mixer/blender and non-symmetric double-cone mixer/blender

21

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

Curing and Slicing Wightman, Muzzio and Wilder10 used low viscosity epoxy and gelatin for glass beads >200 µm. For particles in the size range 50–200 µm, they used solutions of methanol, acetone, and water containing either polyethylene glycol or acrylamides and copolymers in order to achieve satisfactory wetting and solidification. In our case, an inexpensive commercially available low-viscosity solution was used as the infiltrant to freeze the powder mixture. This material held the powder without disruption, bubbles, and any gelatin fragments on the surface. At the end of each mixing experiment, the cup of the vessel was opened, and the solution of infiltrant with low viscosity was slowly dropped on top of the powder mixture using a manifold system with multi-channels. The impregnating solution gradually penetrated the bed of particles, filling voids and displacing air. The infiltrant wet the particles and hardened as the solvent dried. The duration of the infiltration process was 24 h at room temperature, and 96 h inside a furnace at 50°C. The combination of slow impregnation and drying is necessary in order to limit the formation of air bubbles inside the mixture. After curing the liquid infiltrant, the material is extracted from the vessel and sliced by means of a band saw. Multiple cross sections must be examined in order to characterize the entire mixture. Therefore, seven cross sections of mixed powders were examined using a 35 v/o fill ratio and nine sections for the other fill ratios. Figure 3 reveals that the surface of the sections can be far from an ideal, perfect plane, resulting in some noise in the results of the image analysis. Internal cuts result in two surfaces and thus provide two measurements of the same map. Although the two surfaces do not contain the same particles, they

Figure 3. (a) Schematic of infiltrated powders after sectioning and (b) sectioned samples

22

should have the same average composition.16 In addition, we did not analyze the mixture near the wall as material in contact with the end walls moves differently compared with material further away from the walls.17 Thus information obtained by analysis of end-wall observations should not be extrapolated to the entire mixture. Image Acquisition and Quantitative Assessment of Mixedness and Agglomeration The composition of the slices was characterized by a combination of SEM, energy dispersive spectroscopy (EDS), and image analysis. The first step was to acquire backscattered electron images (BSE) of the sections, Figure 4. The number of images for the 35 v/o, 50 v/o, and 65 v/o fill levels were 90, 110, and 130, respectively. The second step was to carry out X-ray mapping of the BSE images using EDS software. Large-area, lowmagnification X-ray maps provide a means of estimating the proportions of different components and determining the chemical and spatial relationships between the components of a composite sample. Spatial relationships, which provide insight on the mode of formation of the constituent phases, are determined by means of image analysis based on a pixel-counting technique. Two X-ray maps were created from one BSE image, Figure 5. The first image showed both iron and ferrosilicon powder and the second image showed only ferrosilicon powder, using Fe Kα and Si Kα X-ray lines (bright pixels). Digital measurements are the core of quantitative image analysis and most are performed on binary images. The estimated v/o is equal to the ratio of the number of pixels that belong to the

Figure 4. Representative micrograph of iron/ferrosilicon mixture (SEM/BSE)

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Next

Table of Contents

Search

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

Figure 5. Representative X-ray maps of iron/ferrosilicon mixture from Figure 4, showing both iron and ferrosilicon, and ferrosilicon phase using Fe Kα and Si Kα X-ray lines, respectively

phase being analyzed to the total number of pixels in the image. The volume ratio (%) VR, of ferrosilicon to iron is calculated from the relation:

(

) (

)

Ferrosilicon Si VR(%)= —————— 100= —————— 100 Iron Fe(TOTAL) – Si

(3)

Where Si = number of bright pixels in the silicon Kα X-ray map, and Fe(TOTAL) = number of bright pixels in the iron Kα X-ray map. In order to assess agglomeration, 100 isolated ferrosilicon particles were measured by dispersing them on a carbon disc and using the method cited. The number of pixels per particle is measured and the average for 100 particles calculated. Subsequently, the size per agglomerate is measured and the average size for each mixing condition is calculated. Orthogonal Array and Experimental Parameters For the Taguchi design and subsequent analysis, Minitab (version 15.0) software was used. The appropriate orthogonal array for the experiment was determined by the software. The most important stage in the design of an experiment lies in the selection of control factors; therefore as many factors as possible should be included and insignificant variables must be identified at the earliest opportunity. The Taguchi method creates an orthogonal array to accommodate these requirements. The selection of a suitable orthogonal array depends on the number of control factors and their levels. In this study, the factors tested were the mixing conditions, not the characteristics of components such as the density ratio or size ratio of the powders. Thus, the primary parameters are the volume-fill ratio of the double cone mixer/blender, mixing speed (rpm) and time Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

(min), which were optimized to obtain the desired results. The three selected control factors and their levels applied in this study are included in Table I. These produced the L-27 orthogonal matrix shown in Table II. As mixing occurred, the intensity of segregation was calculated, as defined by Danckwerts, by means of a parameter I = σ2/σo2, where σ2 is the variance in the composition of the mixture and σo2 is the maximum possible variance corresponding to a completely segregated mixture, which in our study is the initial condition. Thus, the parameter I ranges from 1, when the mixture is completely segregated (i.e., when the concentraTABLE I. FACTORS AND LEVELS IN THE EXPERIMENTS Variable

Fill Ratio

Speed (rpm)

Time (min)

Code Level 1 Level 2 Level 3

A 35 50 65

B 15 20 30

C 10 20 45

TABLE II. L-27 ORTHOGONAL ARRAY (LEVELS OF THREE DIFFERENT FACTORS AND RESULTS) Experiment No.

A

B

C

STDV

ANPA

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

1 1 1 1 1 1 1 1 1 2 2 2 2 2 2 2 2 2 3 3 3 3 3 3 3 3 3

1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3 1 1 1 2 2 2 3 3 3

1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3 1 2 3

2.822 3.185 2.603 4.507 4.973 4.071 3.872 1.551 2.973 3.158 4.091 3.102 4.005 3.938 1.743 2.614 2.789 1.798 3.409 3.292 3.365 5.479 3.068 2.330 3.348 2.948 2.799

1.959 2.228 2.280 2.709 2.111 3.567 2.683 2.225 3.097 2.076 2.257 1.805 2.762 2.388 2.167 2.077 2.307 1.942 1.934 2.082 2.136 2.834 1.813 1.774 2.144 1.988 2.185

23

Previous

1-Page View

2-Page View

Table of Contents

Search

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

tion of species at every point is either 1 or 0) to 0, when it is completely homogeneous. 18 We assumed that the initial condition was considered as completely segregated, thus the intensity of segregation is I = σ2. Consequently, the standard deviation σ (STDV) and average number of particles in each aggregate (ANPA) were used as the response in testing the chemical segregation and size of the agglomerates in the mixture. RESULTS Graphical Representation Typical graphical representation of the degree of mixedness is based on the standard deviation of the measured chemical compositions of the sectioned mixtures, Figure 6. The lower the standard deviation, the more homogeneous is the sample. For example, the first mixing condition (A-35 v/o fill ratio, 30 rpm mixing speed, 20 min mixing time) is more homogeneous compared with the second blending condition (B-50 v/o fill ratio, 20 rpm blending speed, 5 min blending time). Therefore, the dispersion of volume ratios of ferrosilicon to iron in the first mixture was smaller and most of the volume ratios were near the optimum volume ratio (in contrast to the second mixing condition). The dispersion of ferrosilicon powder in the mixture is also illustrated in Figure 7, which is a combination of a BSE image and X-ray map. In the BSE image 7(a), the dispersion of ferrosilicon in the mixture is almost perfect, where the ratio is the same as the optimum. In contrast, when the ferrosilicon-to-iron ratio is 40 v/o, such as in some of the areas in Figure 6(b), the mixture has a high concentration of ferrosilicon powder, Figure 7 (b).

contribution from each factor (P) on the total variation. Once the optimal level of the design parameters is selected, the improvement of the quality characteristic is predicted. The S:N value (ni ) using the optimal level of the design parameters is calculated from the relation: n

ni′ =

Σ (n – n

i=0

i

m)

+ nm

(4)

Figure 6. Frequency distribution of chemical composition as a function of mixing conditions

Statistical Analysis The main objective of ANOVA is to investigate the degree of variation each factor causes relative to the total variation observed in the result. Examination of the calculated values of F* for all control factors is presented in Tables III and IV. When the F value for each design parameter is >4, the design parameter has a significant effect on the quality characteristic. Also, the right-hand columns in Tables III and IV give the percentage *Statistically, the F test (named after Fisher) is used to determine which design parameters have a significant effect on the quality characteristic. The F-ratio is the ratio of mean square error to residual, and is traditionally used to determine the significance of a factor.

24

Figure 7. Combination of BSE and X-ray map, (a) 35 v/o fill ratio, 30 rpm mixing speed, 20 min mixing time, and (b) 50 v/o fill ratio, 20 rpm mixing speed, 5 min mixing time

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Next

Table of Contents

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

where nm is the total mean S:N, ni′ is the mean S:N at the optimal level and n is the number of the main design parameters that affect the quality characteristic. It is obvious from Table III that mixing speed (factor B) and time (factor C) significantly affect the standard deviation of the chemical volume ratio of ferrosilicon to iron. Also, it can be seen in Table IV that the strongest influence on the average number of particles in each aggregate is exerted by the volume-fill ratio of the double-cone mixer/blender (factor A), mixing speed (factor B), and the interaction between the volume-fill ratio and mixing time (A*C). The level average response can be based upon the S:N data. The analysis is performed by averaging the S:N of each level of each factor and plotting the values in graphical form. The level average responses from plots based on the S:N data help to optimize the objective function under study. The peak points in these plots correspond to the optimum condition. The responses of S:N values for control factors are displayed in Tables V and VI, and the level average response plots for various quality characteristics based upon the S:N are shown in Figure 8. Based on the S:N average effect response (Table V and Figure 8 (b)) and ANOVA analysis, the optimal testing parameters for the standard deviation of the chemical volume ratio of ferrosilicon to iron, were the mixing speed at level 3 and mixing time at level 3. Thus, the optimum mixing condition is 30 rpm rotation speed in the double-cone mixer/blender, 45 min mixing time, with any fill ratio (as noted previously, the fill ratio does not influence the standard deviation). Consequently, the factors B3 and C3, which are significant, are used to calculate the standard deviation of the chemical volume ratio of ferrosilicon to iron at the optimum conditions. This was done using equation (3), and found to be 2.260. Similarly, Table IV shows the ANOVA results with respect to the number of particles in each aggregate. Based on the S:N response in Table VI, the level average response plots (Figure 8(a)) and ANOVA analysis, the optimal testing parameters for the average number of particles in each aggregate, are the volume-fill ratio of the double-cone mixer/blender at level 3 (factor A), mixing speed at level 1 (factor B), and the interaction (A*C) between the volume-fill ratio and the mixing time at level 1. Thus, the optimum mixing condition is Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

TABLE III. ANALYSIS OF VARIANCE FOR S:N VALUES OF CHEMICAL SEGREGATION Source

Filling Ratio Speed (rpm) Time (min) Filling Ratio*Speed Filling Ratio*Time Speed*Time Residual Error Total

Degree of Freedom (DOF)

Sum of Squares

Mean of Squares

F

Contribution (%)

2 2 2 4 4 4 8 26

5.669 31.683 31.268 24.885 22.583 28.286 30.707 175.081

2.834 15.842 15.634 6.221 5.646 7.071 3.838

0.74 4.13 4.07 1.62 1.47 1.84

3.238 18.096 17.859 14.213 12.899 16.156 17.539 100

TABLE IV. ANALYSIS OF VARIANCE FOR S:N VALUES OF AVERAGE NUMBER OF PARTICLES IN EACH AGGREGATE Source

Filling Ratio Speed (rpm) Time (min) Filling Ratio*Speed Filling Ratio*Time Speed*Time Residual Error Total

Degree of Freedom (DOF)

Sum of Squares

Mean of Squares

F

Contribution (%)

2 2 2 4 4 4 8 26

12.073 7.208 2.222 4.431 14.314 8.553 7.101 55.903

6.0365 3.6041 1.1112 1.1078 3.5785 2.1383 0.8876

6.80 4.06 1.25 1.25 4.03 2.41

21.596 12.894 3.975 7.926 25.605 15.300 12.702 100

TABLE V. AVERAGE EFFECT RESPONSE FOR S:N ON CHEMICAL SEGREGATION* (A) (B) (C) Filling Blending Blending (A*B) Ratio Speed (rpm) Time (min) Level 1 -10.180 Level 2 -9.243 Level 3 -10.247 Min-Max 1.004 Rank 6

-10.109 -11.094 -8.468 2.626 1

(A*C)

-11.128 -9.066 -9.230 -10.037 -11.121 -9.447 -8.505 -9.484 -10.993 2.623 2.055 1.763 2 4 5

(B*C) No. of Revolutions -8.459 -10.672 -10.540 2.213 3

*Standard deviation TABLE VI. AVERAGE EFFECT RESPONSE FOR S:N ON AGGLOMERATION (A) (B) (C) Filling Blending Blending (A*B) Ratio Speed (rpm) Time (min) Level 1 Level 2 Level 3 Min-Max Rank

-7.943 -6.779 -6.363 1.580 1

-6.354 -7.610 -7.121 1.256 2

-7.331 -6.643 -7.110 0.688 6

(A*C)

-6.502 -6.464 -7.123 -6.696 -7.459 -7.924 0.957 1.460 5 3

(B*C) No. of Revolutions -6.759 -7.699 -6.626 1.073 4

25

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

Figure 8. (a) Level average response graphs for S:N and chemical segregation, (b) Level average response graphs for S:N and average number of particles in each aggregate

a 65 v/o fill ratio for the asymmetrical doublecone mixer/blender, 15 rpm rotation speed, with any mixing time (fill ratio does not influence the average number of particles in each aggregate). Factors A3, C1, and A*C1, which are significant, are used to calculate the average number of particles in each aggregate using equation (3), which is 1.804. If only the main factors are taken into account, i.e., A3 (= 65 v/o fill ratio), B2 (20 rpm rotation speed), and C1 (= 10 min mixing time), the average number of particles in each aggregate is 1.841. The first calculation yielded a smaller value, confirming that the revised optimum is superior. DISCUSSION Rotational Speed A detailed statistical analysis is performed on the effect of cohesive/free-flowing powders in a

26

non-uniform binary system consisting of particles of different sizes. It is shown that the homogeneity and the size of the agglomerates of the free-flowing/cohesive mixtures are a function of mixing rotational speed, namely, facilitating better mixing properties with a small increasing size of aggregates at higher rotational speeds. For small particles or cohesive powders, cohesive forces (attributed primarily to van der Waals interactions for intimate contact) between particles become comparable with particle weights, and small particles can stick to one another in relatively rigid aggregates. According to Chaudhuri et al.,19 the velocity profile of intensely cohesive material shows that single particles do not flow independently; rather, groups of particles act together when force is applied to the entire mass (avalanching). Thus, no mixing is observed. Instead, a cohesive material layer pushes the freeflowing layer and the constituents remain segregated. Also, the cohesive material forms a band and tends to flow coherently in the same direction, hindering the mixing process and creating large agglomerates.19 Higher tumbler speeds (30 rpm) transmit more shear to the system, breaking up the coherent particle bonds, resulting in improved mixing. According to Brone and Muzzio, 1 and Sudah, Coffin-Beach and Muzzio,20 this is because, at rotation rates >10 rpm, the dynamic angle of repose increases and the cascading surface (the region where the material is in rapid flow driven by gravity) becomes curved, with the curvature increasing as the rotational rate is increased, becoming S-shaped.1,20 Consequently, at 30 rpm particles entering the cascading zone of the mixer have enough inertia to separate slightly from the bulk surface and follow free-fall trajectories until they reach (approximately) the center of the mixer and break the aggregates of cohesive material. In addition, as the rotational speed increases, the cascading surface is larger. In general, a larger cascading surface should increase the number of particles in the mixing zone and improve mixing quality. According to Shinbrot, Zeggio and Muzzio21 and Alexander et al.,22–23 at low rotational speeds, trajectory segregation induced by surface flow separates large and small particles. At this location, the mixture of large and small particles enters a bend in the flow, and large particles travel further in the original flow direction before turning. Also, Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

large particles have a tendency to flow outward more readily than smaller particles (larger particles have more inertia and less sur face friction/unit mass). Thus, at low rotational speeds, pattern formation is characterized by separation of components into an inner band of smaller particles surrounded by an outer band of larger particles. With low rotational speeds, there is a tendency to increase size segregation and consequently increase chemical segregation in a non-uniform binary system. At higher tumbler rotational speeds, particle velocities increase mixture crashes into the wall, breaking the cohesiveness of fine particles. Large particles again move towards the surface, but travel faster downwards. The large particles reach the bottom of the granular cascade with less outward displacement than in slower tumblers, and they recoil further inward than smaller particles when they reach the container wall. Thus, small particles percolate through the mix while large particles remain on the surface. Moreover, for finer, more cohesive particles (<30 ?m), the dynamic angle of repose decreases as the rotational speed increases due to fluidization effects and lower particle-wall interaction (friction). 24 Consequently, improved mixing occurs between the larger and smaller particles. Volume-Fill Ratio and Mixing Time According to Brone and Muzzio,1 as the fill ratio decreases, the mixing efficiency increases slightly. The flow in a double-cone mixer/blender has two regions. On the surface of the granular bed is the cascading region, and below this is the rotating region, where the material is compacted. Here, particles are generally locked in place relative to one another and rotate collectively as a solid body. Brone and Muzzio assumed that there is no relative motion of particles in the bulk layer, and mixing can only occur in the cascading layer.1 Thus, as the fill level decreases, a larger fraction of the bed is in the cascading region at any given time, resulting in an increase in the mixing rate. However, according to our statistical analysis on the response of chemical homogeneity, the fill ratio is not a significant factor in relation to chemical homogeneity. This is because the surface area at a 65 v/o fill level in an asymmetrical double-cone mixer/blender may be larger than for a 65 v/o fill, as there is a difference in size in the conical top and bottom in the asymmetrical Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

mixer/blender. Consequently, the 65 v/o fill level gives a longer cascading region, thus enhancing the dispersive mixing rate per revolution. Therefore, there is no significant difference in chemical homogeneity between the 35 v/o and 65 v/o fill ratios. Furthermore, Figure 8 demonstrates that good chemical homogeneity in the mixture with a 35 v/o fill ratio, occurs only with a low mixing speed (15 rpm) for almost all mixing times. The mixture efficiency in the 35 v/o fill ratio has fluctuations as compared with the other fill ratios. The demixing phenomenon occurs in the 35 v/o fill ratio and depends on the mixing speed, time, and number of revolutions. In addition, the smallest fill ratio has the worst agglomeration under almost all mixing conditions. The volume-fill ratio has a significant effect on the size of agglomerates in the mixture, and the optimum condition for the smallest agglomerates is the 65 v/o fill ratio. Consequently, according to our experimental results and Chester et al.,16 the region below the cascade does not strictly rotate as a solid body, but rather the granular bed is slowly deformed along internal slipping surfaces. When layers of material from the surface are incorporated into the granular bed by the flow, they are bent into spirals, thus resulting in even faster radial mixing. The dependence of mixing time on fill levels indicates that optimum utilization of the doublecone mixer/blender would be achieved by operating at 50 v/o and 65 v/o fill levels, in terms of chemical homogeneity and agglomeration, respectively. Also, mixing time and fill ratio are significant factors in relation to chemical homogeneity and the degree of agglomeration, respectively. The interaction between mixing time and fill ratio is also a significant factor for the degree of agglomeration. For all applications, there is always a desire to maximize the batch size (fill ratio) in order to minimize the number of batches. In an industrial setting, where many batches are mixed in sequence and process profitability is affected by total throughput, there is a tendency to run equipment at maximum capacity. In these applications, the moderate decrease in mixing homogeneity and reduction of agglomeration at the 65 v/o fill ratio, and the difficulty in controlling desegregation at the 35 v/o fill ratio, indicates that the optimum fill ratio is 65 v/o. While mixing time will increase, less time will be spent filling and emptying the mixing vessel.

27

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OPTIMIZATION OF METAL POWDER-MIXING PARAMETERS FOR CHEMICAL HOMOGENEITY AND AGGLOMERATION

CONCLUSIONS A well-defined solidification technique has been implemented, providing an experimental tool for preserving and examining the internal structure of powder mixtures. Examination of the internal structure is essential for qualitative evaluation of mixing. Following the Taguchi method of experimental design the effects of various factors influencing per formance characteristics were analyzed. Analysis of the S:N value has been successfully applied, demonstrating the relative contribution of mixing conditions and the optimum factor level combinations for chemical homogeneity and the smallest degree of agglomeration. The study has demonstrated that: • In free-flowing/cohesive mixtures, improved mixing occurs at higher rotational speeds, with a small increase in the size of aggregates. • The fill ratio is not a significant factor in relation to chemical homogeneity in the asymmetrical double-cone mixer/blender. • The mixture efficiency in the 35 v/o fill ratio has fluctuations compared with the other fill ratios. • The volume-fill ratio has a significant effect on the size of agglomerates in the mixture; the optimum condition for the smallest agglomerates is a 65 v/o fill ratio. ACKNOWLEDGEMENTS The authors thank the UK Engineering and Physical Science Research Council (EPSRC) for funding this work. They express gratitude to Höganäs AB and SG Magnets Ltd for the supply of iron and ferrosilicon powders, respectively. N. Vlachos is indebted to PowdermatriX for continuing advice and support. REFERENCES 1. D. Brone and F.J. Muzzio, "Enhanced Mixing in DoubleCone Blenders", Powder Technol., 2000, vol. 110, no. 3, pp. 179–189. 2. F.J. Muzzio, P. Robinson, C. Wightman and D. Brone, "Sampling Practices in Powder Blending", Int. J. Pharm., 1997, vol. 155, no. 2, pp. 153–178. 3. A. Alexander, T. Shinbrot and F.J. Muzzio, "Granular Segregation in the Double-Cone Blender: Transitions and Mechanisms", Phys. Fluids A, 2001, vol. 13, no. 3, pp. 578–587. 4. K.W. Carley-Maculy and M.D. Donald, "The Mixing of Solids in Tumbling Mixers—I", Chem. Eng. Sci., 1962, vol. 17, no. 7, pp. 493–506. 5. K.W. Carley-Maculy and M.D. Donald, "The Mixing of Solids in Tumbling Mixers—II", Chem. Eng. Sci., 1964, vol. 19, no.

28

3, pp. 191–199. 6. M. Poux, P. Fayolle, J. Bertrand, D. Bridoux and J. Bousquet, "Powder Mixing: Some Practical Rules Applied to Agitated Systems", Powder Technol., 1991, vol. 68, no. 3, pp. 213–234. 7. N. Sommier, P. Porion, P. Evesque, B. Leclerc, P. Tchoreloff and G. Couarraze, "Magnetic Resonance Imaging Investigation of the Mixing-Segregation Process in a Pharmaceutical Blender", Int. J. Pharm., 2001, vol. 222, no. 2, pp. 243–258. 8. P.C. Knight, J.P.K. Seville, A.B. Wellm and T. Instone, "Prediction of Impeller Torque in High Shear Powder Mixers", Chem. Eng. Sci., 2001, vol. 56, no. 15, pp. 4,457–4,471. 9. M. Van de Velden, J. Baeyens and K. Smolders, "Solids Mixing in the Riser of a Circulating Fluidized Bed", Chem. Eng. Sci., 2007, vol. 62, no. 8, pp. 2,139–2,153. 10. C. Wightman, F. J. Muzzio and J. Wilder, "A Quantitative Image Analysis Method for Characterizing Mixtures of Granular Materials", Powder Technol., 1996, vol. 89, no. 2, pp. 165–176. 11. J.J. Walker and D.K. Rollins, "Detecting Powder Mixture Inhomogeneity for Non-Normal Measurement Errors", Powder Technol., 1997, vol. 92, no. 1, pp. 9–15. 12. J.J. Walker and D.K. Rollins, "Detecting Powder Mixture Segregation for Multicomponent Mixtures", Chem. Eng. Sci., 1998, vol. 53, no. 4, pp. 651–655. 13. S.H. Park, Robust Design and Analysis for Quality Engineering, 1996, Chapman & Hall, London, UK. 14. D.R. Cox and N. Reid, The Theory of the Design of Experiments, 2000, Chapman & Hall/CRC, London, UK. 15. R. Roy, A Primer on the Taguchi Method, 1990, Van Nostrand Reinhold, New York, NY. 16. A.W. Chester, J.A. Kowalski, M.E. Coles, E.L. Muegge, F.J. Muzzio and D. Brone, "Mixing Dynamics in Catalyst Impregnation in Double-Cone Blenders", Powder Technol., 1999, vol. 102, no. 1, pp.85–94. 17. C. Wightman, P.R. Mort, F.J. Muzzio, R.E. Riman and E.K. Gleason, "The Structure of Mixtures of Particles Generated by Time-Dependent Flows", Powder Technol., 1995, vol. 84, no. 3, pp. 231–240. 18. P.V. Danckwerts, "The Definition and Measurement of Some Characteristics of Mixtures", Appl. Sci. Res., 1952, vol. A3, pp. 279–296. 19. B. Chaudhuri, A. Mehrotra, F.J. Muzzio and M.S. Tomassone, "Cohesive Effects in Powder Mixing in a Tumbling Blender", Powder Technol., 2006, vol. 165, no. 2, pp. 105–114. 20. O.S. Sudah, D. Coffin-Beach and F.J. Muzzio, "Effects of Blender Rotational Speed and Discharge on the Homogeneity of Cohesive and Free-Flowing Mixtures", Int. J. Pharm., 2002, vol. 247, no. 1–2, pp. 57–68. 21. T. Shinbrot, M. Zeggio and F.J. Muzzio, "Computational Approaches to Granular Segregation in Tumbling Blenders", Powder Technol., 2001, vol. 116, no. 2–3, pp. 224–231. 22. A. Alexander, F.J. Muzzio and T. Shinbrot, "Segregation Patterns in V-Blenders", Chem. Eng. Sci., 2003, vol. 58, no. 2, pp. 487–496. 23. A. Alexander, T. Shinbrot, B. Johnson and F.J. Muzzio, "VBlender Segregation Patterns for Free-Flowing Materials: Effects of Blender Capacity and Fill Level", Int. J. Pharm., 2004, vol. 269, no. 1, pp. 19–18. 24. A. Castellanos, J.M. Valverde, A.T. Pérez, A. Ramos and P. Keith Watson, "Flow Regimes in Fine Cohesive Powders", Phys. Rev. Lett., 1999, vol. 82, no. 6, pp. 1,156–1,159. ijpm

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

RESEARCH & DEVELOPMENT

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION Nikolaos Vlachos* and Isaac T. H. Chang**

INTRODUCTION Efficient mixing and sampling of powders are crucial in the manufacture of many products, including powder metallurgy (PM) parts, pharmaceuticals, ceramics, catalysts, glass, cement, and magnetic media. The preparation of powder mixes is essential in order to obtain the required alloy compositions, at relatively low cost and with adequate compressibility. Mixing of powders plays a major role in the quality and consistency of PM parts.1 Design and optimization of powder mixing operations require accurate methods for determining the quality of the mixture. In the present study, we describe a method for obtaining a quantitative characterization of mixes of industrial metal powders. In addition, we assess the effect of mixing orientation on the uniformity of the mixture and the effect of the mixing parameters (fill ratio, rotational speed, and time) on the uniformity of the powder mix in the axial and radial directions.

A uniform powder mixture is important for product consistency and quality. Therefore, it is important to optimize the mixing conditions, which include fill ratio, rotational speed, and time, in order to achieve a powder mixture with a high degree of mixedness without aggregates. Chemical segregation and agglomeration within the powder mix can be assessed quantitatively using a “freezing” technique which holds the powder particles in place with minimal disruption of their positions. Using analysis of variance (ANOVA) and a Taguchi analysis, the effect of mixing orientation on the uniformity of the mixture, and the effect of mixing parameters on uniformity in the axial and radial directions, were investigated. Based on the statistical analysis, rotational speed and volume-fill ratio are the predominant processing parameters in axial and radial mixing, respectively. Axial and radial mixing give the same number of mean particles per aggregate.

Sampling in Powder Mixing A thief probe is the most common method used in the PM industry to characterize mixtures.2–7 However, the mixture is disturbed when the thief probe is inserted into the powder bed such that the sample that is finally collected is likely to contain particles from all positions along the path.1–4 In addition, particles of different sizes often flow unevenly into the thief cavities.2,3 Another common method for sampling powder mixes is the colorimetric technique. This involves mixing coarse particles with pigments or glass beads of different color. However, this technique has the disadvantage of giving information only at the walls, and is not applicable to industrial powders.1,6,7,9 In order to perform a dynamical analysis of the interior of a granular bed, different techniques have been used, such as magnetic resonance imaging3,7–10 and positron emission parti-

*PhD Research Student, **Senior Lecturer, School of Metallurgy and Materials, The University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom; E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

29

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

cle tracking.3,11,12 These techniques are complex and expensive to set up and can only be used in a dedicated laboratory. Thus, powder mixing is a core problem in the PM industry because of the lack of suitable techniques for sampling particulate mixtures without disturbing their structure. Our method involves curing or “freezing” the powder mix to preserve its structure, facilitating subsequent observation.3,13 This technique permits the assessment of local mixture composition as a function of position in the mix. Another advantage of this method is the direct observation of the complete structure of the mixture, and mixing patterns can be viewed both internally and at exposed surfaces. The main weakness of the technique is that the sample is sacrificed during the analysis, thus requiring a series of experiments in order to analyze the time evolution of the mixing process. Mixing Indices The most widespread method to assess the homogeneity of a powder mix, established by Lacey,5,9,14–16 is the application of mixing indices. A mixing index is a ratio of terms that represents different functions of sample variability (sampling error). To be an efficient indicator of mixedness, the true value of the ratio should be influenced only by the existence of segregation, and should otherwise remain constant. However, current indices exhibit several fundamental limitations that make them unattractive as measures of mixedness.16 Their main constraint is a failure to control the effect of sampling variability. This insensitivity permits indices to deviate considerably from the value representing ideal mixing for reasons other than the inhomogeneity of the mixture. Furthermore, the present indices cannot be used to statistically control false conclusions regarding the non-existence or existence of segregation, because their statistical distributions have not been specified. Thus, it is not possible to accurately identify the sample size, nor make other significant statistical inferences using index values.16 The seven indices examined by Walker and Rollins17,18 and reviewed by Poux et al.9 are given in Table I.5,9,17–19 (The notations in Table I and other notations used in this paper are listed in the Appendix.) Analysis of the true values of the seven indices will demonstrate that these ratios are not responsive to segregation alone. Since

30

TABLE I. MIXING INDICES14

these indices are affected by factors other than segregation, we have concluded that they are undesirable as measures of segregation.17–19 ANOVA Analysis The method utilized to assess the mixedness of mixtures is ANOVA. It is a statistical technique that uses a test statistic representing an appropriate ratio to isolate the effect of segregation. The test statistic has a known distribution so that it is possible to control error rates for false conclusions. In addition, it is possible to specify the confidence interval for true values, or combinations of true values, for the parameters of interest.20–22 “One-way” ANOVA is used to compare the means of a numerical outcome variable in the groups defined by an exposure level with two or more categories. The method is based on assessing how much of the overall variation in the outcome is attributable to differences between the exposure-group means. The null hypothesis states that the outcome does not differ between exposure groups and is based on a comparison of the “between-groups” and “within-groups” mean squares.23 The mean squares are compared using the F test, sometimes called the variance-ratio test. F=

Between Groups MS ——————————— Within Groups MS

(1)

d.f. (Between Groups) = k-1

(2)

d.f. (Within Groups) = n-k

(3)

where MS is the mean square (variation per degree of freedom), d.f. is the degree of freedom, n is the total number of observations (sampling area) and k is the number of groups (surface areas).23 F should be approximately 1 if there are Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Next

Table of Contents

Search

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

no real differences between the groups and >1 if there are real differences. Taguchi Method The aim of the Taguchi approach is to identify the best product or process characteristic that minimizes sensitivity to noise. The Taguchi design can be used to define the effect of mixing conditions on characteristic properties and the best combination of conditions.24,25 This simple and systematic approach is used to optimize design for performance, quality and cost. 13,14 In the Taguchi approach, orthogonal arrays and ANOVA are used as the analytical tools. ANOVA can estimate the effect of a factor on the characteristic properties, and experiments can be performed with minimum replication, using the orthogonal arrays. Conventional statistical experimental design can determine the optimal conditions on the basis of the measured values of the characteristic properties, while the Taguchi method can determine the experimental conditions resulting in the least variability from the optimal condition. The variability is expressed by signal-to-noise ratio (S:N). The terms “signal” and “noise” represent the desirable and undesirable values for the output characteristic, respectively. The Taguchi method uses the S:N value to measure the quality characteristic deviating from the desired value. The experimental condition having the maximum S:N is considered as the optimal condition as the variability characteristics are inversely proportional to the S:N.13,14 There are three categories of quality characteristics in the analysis of the S:N, namely, “thelower -the-better,” “the-higher -the-better,” and “the-nominal-the better.”24,25 In this study, thelower-the-better quality characteristic was used. The S:N value of each level of testing parameters was computed based on the S:N analysis. “Thelower-the-better” is usually the chosen S:N for all undesirable characteristics such as “defects,” for which the ideal value is zero. Also, when an ideal value is finite and its maximum or minimum values are defined, the difference between measured data and the ideal value is expected to be as small as possible. The generic form of the S:N then becomes: S:N = -log (1/n ) Σy2i

(4)

where yi is the primary response and n is the number of repetitions of each experiment. Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Experimental Methods Quantitative experiments were performed using a free-flowing powder and a cohesive ferrosilicon powder (Figure 1) loaded into horizontal layers in a non-symmetrical double-cone mixer/blender, with a volume capacity of 1 L. The iron powder had a mean diameter of 102.5 µm and an apparent density of 3.041 g/cm3. The ferrosilicon powder had a mean diameter of 25 µm and an apparent density of 2.081 g/cm3. The nominal composition of the mixture was 6 w/o ferrosilicon and 94 w/o Fe (equivalent to 9.38 v/o ferrosilicon and 90.62 v/o iron). Mixing was performed using a Pharmatec Multi-blender MB 015. Fill levels between 35 v/o and 65 v/o were used and speeds between 15 and 30 rpm were evaluated. Each experiment was run for a predetermined mixing time, between 10 and 45 min. Subsequently, quantitative data were obtained utilizing image analysis, using a combination of scanning electron microscopy (SEM) and image analyzer software. The factors that influence the homogeneity of the mixture in the axial and radial orientations used in this experiment included only the mixing conditions and not the characteristics of the components. Thus, the primary parameters were the volume-fill ratio of the double-cone mixer/ blender, the rotational speed (rpm) and the time (min), which were optimized to achieve the desired results. These parameters and their levels are cited in Table II.

Figure 1. (a) Iron powder (irregular shape) and (b) ferrosilicon powder (large particles have irregular shape, smaller particles are spherical). SEM

TABLE II. MIXING PARAMETERS AND LEVELS Variables

Fill Ratio

Level 1 Level 2 Level 3

35 50 65

Rotational Speed (rpm) Time (min) 15 20 30

10 20 45

31

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

At the completion of each experiment, the entire mixture was solidified inside the mixing vessel to preserve the structure of the mixture during subsequent characterization, using an infiltrant solution of low viscosity, following the technique described by Vlachos and Chang. 26 After curing the liquid infiltrant, the structure was extracted from the vessel and sliced by means of a band saw. Seven cross sections were examined using a 35 v/o volume-fill ratio and nine sections for the other volume-fill ratios. The composition of the slices was characterized by a combination of SEM, EDS (Inca software), and image analysis software (KS400, 3.0). A representative backscattered SEM micrograph of one of the samples of mixed iron/ferrosilicon powder is shown in Figure 2; this micrograph shows that the solidified binding agent forms bridges between the particles. The number of samples for the 35 v/o, 50 v/o, and 65 v/o fill levels were 90, 110, and 130, respectively.26 Two X-ray maps were created from one backscattered electron image (BSE), Figure 3. The first showed both iron and ferrosilicon powders, and the second showed only ferrosilicon powders, using Fe Kα and Si Kα X-ray lines (bright pixels). The estimated v/o is equal to the ratio of the number of pixels that belong to the phase analyzed to the total number of pixels in the image (determined via image analysis based on a pixel counting technique).26 Therefore, the calculated volume ratio (V R ) of ferrosilicon to iron is expressed as: Ferrosilicon Si VR = —————— = ——————— Iron Fe(TOTAL) – Si

Figure 3. Representative X-ray maps of iron/ferrosilicon mix (from Figure 4), showing (a) iron and ferrosilicon, and (b) ferrosilicon using Fe Kα and Si Kα X-ray lines

powder mixtures in different orientations. The cited parameters and their levels produced the L27 orthogonal matrix. All output responses need to be kept to a minimum.

(5)

Si = Number of bright pixels in Si Kα X-ray map Fe(TOTAL) = November of bright pixels in Fe K α X-ray map To test agglomeration, 100 isolated ferrosilicon particles were measured by dispersing them on a carbon disc and using the method described. The number of pixels per particle was measured and the average number for 100 particles calculated. Subsequently, the size of each agglomerate and the average size of the agglomerates for each of the mixing conditions were calculated For the Taguchi design and subsequent analysis, Minitab (version 15.0) software was used. The standard deviation σ (STDV) was used as a response for testing chemical segregation in the

32

Figure 2. Representative micrograph of iron/ferrosilicon mixture. SEM/BSE

RESULTS & DISCUSSION Effect of Axial and Radial Mixing on Uniformity and Agglomeration of Mixes For the purpose of these studies, the orientation of the areas of the mixture sectioned horizontally is defined as the X-orientation (axial mixing), and the orientation perpendicular to the axial mixing as the Y-orientation (radial mixing). The Zorientation is a combination of axial and radial mixing. To investigate any orientation effects on mixedness, three spaced sites in each orientation were used (except for the 35 v/o fill ratio in the Y and Z orientation). These sites were labeled X1, X2, X3; Y1, Y2, Y3; and Z1, Z2, Z3, respectively. Each site was sampled multiple times and the mean of the ratios of ferrosilicon to iron taken. The value of this ratio changes, depending on the Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Next

Table of Contents

Search

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

TABLE III. MIXING CONDITIONS, MEAN VALUE OF FERROSILICON-TO-IRON RATIO OF EACH SURFACE, AND AVERAGE NUMBER OF PARTICLES PER AGGREGATE PER ORIENTATION No. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27

Factors

X- Axial Mixing

F.R.

Sp.

T.

X1

X2

X3

35 35 35 35 35 35 35 35 35 50 50 50 50 50 50 50 50 50 65 65 65 65 65 65 65 65 65

15 15 15 20 20 20 30 30 30 15 15 15 20 20 20 30 30 30 15 15 15 20 20 20 30 30 30

10 20 45 10 20 45 10 20 45 10 20 45 10 20 45 10 20 45 10 20 45 10 20 45 10 20 45

6.47 5.26 9.49 6.90 9.77 7.58 9.41 8.39 8.61 7.30 8.73 6.99 13.54 7.89 9.34 6.66 9.83 9.42 5.15 4.72 5.72 12.95 11.65 9.01 9.75 7.39 9,40

8.40 5.21 11.40 7.92 9.91 9.11 13.02 8.60 11.03 9.90 12.65 10.09 4.40 9.87 10.23 9.88 10.35 9.75 6.54 9.77 13.97 15.03 12.22 10.11 9.56 9.51 9.18

9.55 9.53 8.04 6.13 9.08 7.28 7.42 8.80 11.19 9.09 10.46 10.25 9.06 12.17 9.47 9.43 11.02 9.57 7.71 8.51 10.95 17.48 9.31 9.85 12.19 10.04 10.68

Y- Radial Mixing

Xave Agglomeration STDV Y1 8.14 6.66 9.65 6.98 9.59 7.99 9.95 8.59 10.28 8.76 10.61 9.11 9.00 9.98 9.68 8.66 10.40 9.58 6.47 7.67 10.21 15.15 11.06 9.65 10.50 8.98 9.75

1.891 2.088 2.352 2.053 1.992 2.648 2.147 2.142 2.059 2.117 2.392 1.947 3.036 2.353 2.195 2.066 2.382 2.100 1.843 1.863 2.359 2.964 1.647 2.003 2.165 2.235 2.232

1.55 1.09 1.41 2.76 3.12 3.91 2.21 1.73 1.71 1.86 1.92 1.69 2.90 2.97 1.01 1.33 1.68 1.69 1.28 2.46 2.11 3.30 3.00 1.84 1.90 1.50 1.66

mixing conditions. In addition, the average number of particles in each aggregate was investigated in the X and Y orientations. The overall test arrangements and the resultant outputs are listed in Table III. An ANOVA statistical procedure was used to determine whether the means from two or more samples were drawn from populations with the same mean value. The ANOVA results are listed in Table IV. These results reveal that there is a significant difference in the uniformity of the mixture between radial and axial mixing with p-values of 0.832 and 0.027 respectively, at the significance level α = 0.05. As the p-value is a measure of how much evidence there is to support the “no-significant difference” hypothesis, the higher the p-value, the more evidence there is. As the axial mixing has a p-value <0.05, the null hypothesis is rejected, and the variance of the mean value of the ratio of ferrosilicon to iron in axial mixing is shown to be much higher than in radial mixing for all conditions. In Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

12.15 6.34 10.24 11.24 9.55 10.10 6.80 10.01 9.78 8.39 11.45 5.83 4.93 10.43 11.19 10.49 11.01 9.51 11.40 8.37 7.72 10.81 8.80 10.70 8.28 9.19 11.19

Y2 8.35 8.27 9.77 15.03 10.06 14.85 12.06 9.97 9.04 5.73 7.90 6.37 7.78 6.61 9.54 10.79 9.34 9.26 12.25 12.17 8.24 9.46 10.83 10.19 9.62 11.78 10.95

Y3

5.32 8.45 6.03 7.89 7.94 9.93 10.33 10.33 9.86 5.45 11.38 8.50 17.28 10.36 8.49 12.95 13.72 9.49

Z-Orientation

Yave Agglomeration STDV 10.25 7.30 10.00 13.14 9.81 12.47 9.43 9.99 9.41 6.48 9.27 6.07 6.87 8.33 10.22 10.53 10.23 9.54 9.70 10.64 8.15 12.51 10.00 9.79 10.28 11.56 10.54

1.962 2.109 2.303 2.808 1.774 3.901 2.141 2.304 2.012 1.917 2.005 1.753 2.181 2.256 2.213 2.055 2.386 1.961 2.154 2.254 2.142 2.722 2.003 1.637 1.959 2.037 2.071

2.55 1.99 2.69 2.72 0.98 1.76 2.06 1.30 3.25 1.48 3.72 1.55 2.10 3.01 1.73 2.01 1.57 1.44 2.76 3.64 1.57 4.86 1.54 2.44 3.64 2.80 2.91

Z1

Z2

12.39 8.45 8.13 14.22 13.06 12.26 16.19 10.08 9.63 8.28 15.51 9.70 9.35 10.94 11.91 10.51 14.76 10.91 7.67 8.65 7.26 11.32 11.02 10.43 12.34 10.36 11.01

8.41 11.64 11.24 6.78 12.00 11.89 14.91 10.08 8.25 9.84 14.91 9.40 12.77 11.29 10.28 9.03 11.45 10.53 5.22 7.88 9.25 17.28 14.99 12.26 9.62 10.26 9.56

Z3

Zave

12.98 10.62 8.96 11.99 10.55 9.61 12.15 13.23 9.47 6.86 10.19 6.97 10.98 7.85 9.85 10.45 10.60 9.13

10.40 10.04 9.68 10.50 12.53 12.07 15.55 10.08 8.94 10.37 13.68 9.35 11.37 10.93 10.60 10.57 13.15 10.30 6.58 8.91 7.83 13.19 11,29 10.85 10.80 10.41 9.90

TABLE IV. EFFECT OF RADIAL AND AXIAL MIXING ON UNIFORMITY (ANOVA) Orientation Source of Variation

S.S

d.f.

M.S.

F

p-value

X-Axial Mixing

Between X-Sites Within X-Sites Total

36.94 381.03 417.98

2 78 80

18.47 3.78 4.89

0.027

Y-Radial Mixing

Between Y-Sites Within Y-Sites Total

1.98 372.24 374.23

2 69 71

0.99 5.39

0.18

0.832

Between (X&Y) Orientations Within Orientations Total

3.22 792.21 795.43

1 151 152

3.22 5.25

0.61

0.434

Between Z-Sites Within Z-Sites Total

7.96 382.79 390.75

2 69 71

3.98 555

0.72

0.492

Z-Orientation

other words, the sites, which are influenced by radial mixing, are more homogeneously distributed than those influenced by axial mixing. This is supported by the fact that the sum of the

33

Previous

2-Page View

1-Page View

Search

Next

Table of Contents

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

squared deviation of the between X-sites (36.94) is much higher than that of the between Y-sites (1.98). Thus, it is clear that there is minimal mixing between the components across the vertical interface. Consequently, mixing along the rotational axis is much slower than in the radial direction. Also, for all fill ratios between 150 and 300 revolutions, there is a large fluctuation in the average concentration of ferrosilicon between the sections. According to Chester et al.,27 the characteristic time scale for axial mixing is 20 to 40 times longer than the characteristic time scale for radial mixing. Although a significant difference in the uniformity of the mixture between radial and axial mixing was demonstrated, the ANOVA results indicate that there is no significant difference between orientations, with a p-value of 0.434 at the significance level of 0.05. This is attributed to the sites of the X and Y orientation having similar mean values, but different STDV values, as noted previously. When ANOVA was applied between orientations, the orientation with the smallest STDV had the most dominant influence on the pvalue. In addition, the ANOVA results for the Zorientation, which is a combination of the other two orientations, are similar to those for the X-Y orientations. The Paired-Sample t-Test procedure compares the means of average particles in each aggregate in two orientations (axial and radial mixing), and

is used to investigate the effect of orientation on agglomeration. A low significance value for the tTest (typically <0.05) indicates that there is a significant difference between the two orientations. Also, if the confidence interval for the mean difference does not contain zero, this difference is significant. According to Table V, the average number of particles in each aggregate in axial and radial mixing does not vary significantly. Effect of Operational Parameters on Uniformity of Mixture (STDV) ANOVA ANOVA was applied to the uniformity of the mixture (STDV) in axial and radial mixing. The results are given in Table VI, in which the parameters that have a significant effect on the uniformity of the mixture are highlighted. This illustrates that different parameters have varied effects on the resultant surface uniformity. The rotational speed of the double-cone mixer/blender is shown to play an important role, and has a significant effect on uniformity of mixing in the axial direction. Also, the F value for each design parameter was calculated. When F > 4 the design parameter has a significant effect on the quality of the characteristics. Therefore, the rotational speed has a significant effect on the uniformity of mixing of the resultant surface in axial mixing. As the rotational speed increases (up to 20 rpm), the homogeneity of the mixture in the axial orienta-

TABLE V. PAIRED SAMPLE t-TEST OF MEAN NUMBER OF PARTICLES PER AGGREGATE IN X-Y (AXIAL-RADIAL) MIXING Agglomeration Pair 1 AxialRadial Mixing

Paired Differences Mean

0.009

STDV

STDV Error Mean

0.389

t

d.f.

Sig. (2-Tailed)

0.124

26

0.902

95% Confidence Interval of Difference

0.075

Upper

Lower

-0.145

0.163

TABLE VI. EFFECT OF MIXING PARAMETERS ON THE SURFACE IN AXIAL AND RADIAL MIXING (THE-SMALLER-THE-BETTER): ANOVA RESULTS Parameter

Orientation

SS

Fill Ratio 4.966 Speed X- Axial Mixing 97.226 Time 5.838 FR*Speed 44.681 FR*Time 17.932 Revolution 37.872 Residual Error 61.229 Total 269.744

34

d.f.

MS

F

2 2 2 4 4 4 8 26

2.483 48.613 2.919 11.17 4.483 9.468 7.654

0.32 6.35 0.38 1.46 0.59 1.24

p-Value

Orientation

SS

0.732 0.022 Y- Radial Mixing 0.695 0.3 0.682 0.368

d.f.

55.931 2 4.195 2 24.795 2 31.372 4 88.669 4 68.53 4 36.038 8 309.53 26

MS

F

p-Value

27.965 2.097 12.398 7.843 22.167 17.133 4.505

6.21 0.47 2.75 1.74 4.92 3.8

0.021 0.644 0.123 0.234 0.027 0.051

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

Figure 4. Level average response graphs by S:N of chemical segregation; (a) Y-orientation (radial mixing), and (b) X-orientation (axial mixing)

tion increases for all fill ratios (Table III). Over 20 rpm and with a long period of mixing (45 min), homogeneity decreases. There are two effects present when the rotational speed is changed. The first effect is predominant with rotational speeds <20 rpm. As the rotational speed increases, the curvature is more pronounced and the size of the cascading region increases. Thus, there are a larger number of particles in the mixing zone and this increases the homogeneity of the mixture in the axial direction. The second effect is that, as the rotational speed is increased >20 rpm, particles move at a higher velocity. For faster moving particles, random dispersive motion in the axial direction may decrease relative to the increased convective motion in the radial direction; this tends to decrease mixing.1 However, the ANOVA results indicate that the volume-fill ratio of the double-cone mixer/blender has a significant effect on the resultant surface uniformity in radial mixing. The other parameters play a less important role. Under most mixing conditions, when the fill ratio is increased, the uniformity of the mixture is decreased in the radial direction. Based on Table III, these observations are confirmed when the comparison is made between 50 v/o and 65 v/o fill ratios of the double-cone mixer/blender. The average STDV for all mixing conditions in each volume ratio is increased with increasing volume ratio. Thus, the homogeneity of the mixture in the radial direction is decreased. Flow in the double-cone mixer/blender exhibits two regions. The first is the cascading region, which is on the surface of the granular bed where the materials are dilated and in rapid flow, driven by gravity. Below the Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

cascading region is the rotating region where the material is compacted. There is no relative mobility of particles in the bulk layer, and mixing can only occur in the cascading region. Thus, as the fill level decreases, a larger fraction of the bed is in the cascading region at any given time, resulting in an increase in homogeneity of mixing, especially in the radial direction. Level Average Response Analysis The average response analysis can be based upon the S:N and is performed by averaging the S:N data at each level for each factor and plotting the values in graphical form. The level average responses from the plots based on S:N data are helpful in optimization of the objective function under study, Figure 4. The peak points in these plots correspond to the optimum condition. In addition, the control factor with the strongest influence is determined by using the value of the difference between the S:N in the smallest and largest levels. The higher the difference, the more influential the control factor or the interaction between two controls is. Hence, it is demonstrated that the optimum mixing conditions for achieving uniformity in axial mixing are a 65 v/o fill ratio, 20 rpm rotational speed, for 20 min. Correspondingly, the 65 v/o fill ratio, 15 rpm rotational speed for 10 min is the optimum combination of parameters for achieving uniformity in radial mixing. CONCLUSION • Sites that are influenced by radial mixing are more homogeneously distributed than those influenced by axial mixing.

35

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

• The average number of particles in each aggregate in axial and radial mixing does not vary significantly. • As the rotational speed increases (up to 20 rpm), the homogeneity of the mixture in the axial orientation increases, for all fill ratios. Over 20 rpm, and with a long period of mixing (45 min), homogeneity decreases. • Under most mixing conditions, when the fill ratio is increased, the uniformity of the mixture in the radial direction is decreased. • Optimum conditions for achieving uniformity in axial mixing are a 65 v/o fill ratio, 20 rpm rotational speed, for 20 min. The 65 v/o fill ratio, at 15 rpm speed for 10 min is the optimum combination of processing parameters for achieving uniformity in radial mixing. ACKNOWLEDGEMENTS The authors thank the UK Engineering and Physical Science Research Council (EPSRC) for funding this work. They express thanks to Höganäs AB and SG Magnets Ltd for the supply of iron and ferrosilicon powders, respectively. N. Vlachos is indebted to PowdermatriX for continuing advice and support.

11.

12.

13.

14.

15.

16.

17.

18.

19.

REFERENCES 1. D. Brone and F.J. Muzzio, "Enhanced Mixing in DoubleCone Blenders", Powder Technol., 2000, vol. 110, no. 3, pp. 179–189. 2. F.J. Muzzio, P. Robinson, C. Wightman and D. Brone, "Sampling Practices in Powder Blending", Int. J. Pharm., 1997, vol. 155, no. 2, pp. 153–178. 3. P.L. Edward, Handbook of Industrial Mixing: Science and Practice, 2004, John Wiley & Sons, Hoboken, NJ. 4. A. Alexander, T. Shinbrot and F.J. Muzzio, "Granular Segregation in the Double-Cone Blender: Transitions and Mechanisms", Phys. Fluids A, 2001, vol. 13, no. 3, pp. 578–587. 5. K.W. Carley-Maculy and M.D. Donald, "The Mixing of Solids in Tumbling Mixers—I", Chem. Eng. Sci., 1962, vol. 17, no. 7, pp. 493–506. 6. K.W. Carley-Maculy and M.D. Donald, "The Mixing of Solids in Tumbling Mixers—II", Chem. Eng. Sci., 1964, vol. 19, no. 3, pp. 191–199. 7. R. Hogg, D.S. Cahn, T.W. Healy and D.W. Fuerstenau, "Diffusional Mixing in an Ideal System", Chem. Eng. Sci., 1966, vol. 21, no. 11, pp. 1,025–1,038 8. K.M. Hill and J. Kakalios, Phys. Rev. Lett., 1997, vol. 78, pp. 50–53. 9. M. Poux, P. Fayolle, J. Bertrand, D. Bridoux and J. Bousquet, "Powder Mixing: Some Practical Rules Applied to Agitated Systems", Powder Technol., 1991, vol. 68, no. 3, pp. 213–234. 10. N. Sommier, P. Porion, P. Evesque, B. Leclerc, P. Tchoreloff and G. Couarraze, "Magnetic Resonance

36

20.

21.

22. 23. 24. 25. 26.

27.

Imaging Investigation of the Mixing-Segregation Process in a Pharmaceutical Blender", Int. J. Pharm., 2001, vol. 222, no. 2, pp. 243–258. Y.L. Ding, J.P.K. Seville, R. Foster and D.J. Parker, "Solids Motion in Rolling Mode Rotating Drums Operated at Low to Medium Rotational Speeds", Chem. Eng. Sci., 2001, vol. 56, no. 5, pp. 1,769–1,780. P.C. Knight, J.P.K. Seville, A.B. Wellm and T. Instone, "Prediction of Impeller Torque in High Shear Powder Mixers", Chem. Eng. Sci., 2001, vol. 56, no. 15, pp. 4,457–4,471. C. Wightman, F.J. Muzzio and J. Wilder, "A Quantitative Image Analysis Method for Characterizing Mixtures of Granular Materials", Powder Technol., 1996, vol. 89, no. 2, pp. 165–176 . K.R. Derrick, D.L. Faust and D.L. Jabas, "A Superior Approach to Indices in Determining Mixture Segregation", Powder Technol., 1995, vol. 84, no. 3, pp. 277–282. W.J. Thiel and P.L. Stephenson, "Assessing the Homogeneity of an Ordered Mixture", Powder Technol., 1982, vol. 31, no. 1, pp. 45–50. J.A. Hersey, "Powder Mixing: Theory and Practice in Pharmacy", Powder Technol., 1976, vol. 15, no. 2, pp. 149–153. J.J. Walker and D.K. Rollins, "Detecting Powder Mixture Inhomogeneity for Non-normal Measurement Errors", Powder Technol., 1997, vol. 92, no. 1, pp. 9–15. J.J. Walker and D.K. Rollins, "Detecting Powder Mixture Segregation for Multicomponent Mixtures", Chem. Eng. Sci., 1998, vol. 53, no. 4, pp. 651–655. H.G. Kristensen, "Statistical Properties of Random and Non-random Mixtures of Dry Solids: Part II, VarianceSample Size Relationships Derived by Autocorrelation Theories", Powder Technol., 1973, vol. 8, no. 3–4, pp. 149–157. W.J. Diamond, Practical Experiment Designs: For Engineers and Scientists, Third Edition, 2001, John Wiley & Sons, New York, NY. G. Taguchi, Y. Yokoyama and Y. Wu, Methods/ Design of Experiments, (Taguchi Methods Series) 1993, American Supplier Institute (ASI) Press, Tokyo, Japan. S.H. Park, Robust Design and Analysis for Quality Engineering, 1996, Chapman & Hall, London, UK. D.R. Cox and N. Reid, The Theory of the Design of Experiments, 2000, Chapman & Hall/CRC, London, UK. C. Douglas: Design and Analysis of Experiments, Fifth Edition, 2001, John Wiley & Sons, New York, NY. R. Roy, A Primer on the Taguchi Method, 1990, Society of Manufacturing Engineers, Dearborn, MI. N. Vlachos, I.T.H. Chang, "Taguchi Optimization of the Distribution and Agglomeration of Nickel Powder (T123 & T110) in Blended Iron-Nickel Powder Mixture", Advances in Powder Metallurgy and Particulate Materials—2008, compiled by R. Lawcock, A. Lawley and P.J. McGeehan, Metal Powder Industries Federation, Princeton, NJ, 2008, vol. 1, part 2, pp. 1,479–1,489. A.W. Chester, J.A. Kowalski, M.E. Coles, E.L. Muegge, F.J. Muzzio and D. Brone, "Mixing Dynamics in Catalyst Impregnation in Double-Cone Blenders", Powder Technol., 1999, vol. 102, no. 1, pp. 85–94.

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

EFFECT OF AXIAL AND RADIAL METAL POWDER MIXING ON CHEMICAL HOMOGENEITY AND AGGLOMERATION

APPENDIX S2Np = estimated variance due to number of particles in measured sample S2o = estimated variance for choosing a particle of A when randomly sampling one particle in the mixture S2T = estimated total sample variance Np = number of particles pˆ = average measured composition of A for all NR regions p = overall true proportion of A in mixture σ 2Np = true variance due to number of particles in measured sample σ 2o = true variance for choosing a particle of A when randomly sampling one particle in the mixture σ 2T = true total variance which includes all possible sources of variation 2 = true total variance within a region excluσSE sive of σ2Np 2 σ τ = true variance due to segregation (different pjs) F = variance ratio SS = sum of squares ( = Σ (x – –x )2 ) (x – x– ) = deviation of observation from mean MS = mean square (amount of variation per degree of freedom) d.f. = degree of freedom n = total number of observations k = number of groups (surface areas) p-value = strength of evidence against null hypothesis α = percentage point of normal distribution S:N = signal to noise ratio VR = volume ratio ferrosilicon to iron ijpm

TRUST must be earned For 90 years, ACuPowder has been delivering the finest quality powders and the most conscientious service. Our customers know that serving their needs and solving their problems is our highest priority. Bring us your toughest assignments. We want to earn your trust, too. The finest powders are from ACuPowder: Copper, Tin, Bronze, Brass, Copper Infiltrant, Bronze Premixes, Antimony, Bismuth, Chromium, Manganese, MnS+, Nickel, Silicon, Graphite and P/M Lubricants.

901 Lehigh Ave., Union, NJ 07083 908-851- 4500, • Fax 908-851- 4597

6621 Hwy. 411 So., Greenback, TN 37742 865- 856- 3021 • Fax 865-856 -3083 e-mail: [email protected] web: www.acupowder.com ISO 9001 CERTIFIED

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

ISO 14001 CERTIFIED

37

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

OUTSTANDING TECHNICAL PAPER: PM 2008 WORLD CONGRESS

DEVELOPMENT OF A DUAL-PHASE PRECIPITATIONHARDENING PM STAINLESS STEEL Christopher T. Schade*, Thomas F. Murphy, FAPMI**, Alan Lawley, FAPMI*** and Roger D. Doherty****

INTRODUCTION In the competition between wrought and PM stainless steels, PM materials are at an extreme disadvantage due to the deleterious effect of porosity on mechanical properties such as tensile strength, ductility, and impact toughness. Furthermore, the use of increased alloy levels in PM stainless steels is both costly and counterproductive due to their negative effect on compressibility. The addition of graphite, which is used for increasing mechanical properties in ferrous PM, is detrimental to the corrosion resistance of PM stainless steels and reduces ductility. In order to achieve improved mechanical properties and enhance corrosion resistance in PM stainless steels, it is necessary to explore nontraditional strengthening mechanisms. It has been shown that utilizing a dual-phase microstructure can lead to increased strength in a PM stainless steel.1–3 The microstructure is a combination of ferrite and martensite, Figure 1. The ferrite allows for a higher sintered density, improving ductility and toughness, while the martensite imparts strength and hardness. The levels of martensite and ferrite can be balanced by adjusting the content of the austenite stabilizers (nickel and copper) and the ferrite stabilizers (chromium, silicon, and molybdenum). One of the most common dual-phase PM stainless steels, SS-409LNi (Table I), is commonly used for exhaust flanges. The ferritic microstructure of SS-409L is altered by admixing nickel which promotes the formation of high-temperature austenite during sintering, and which transforms to martensite during cooling. Precipitation-hardening stainless steels are not defined by their microstructure, but rather by the strengthening mechanism. These grades can have austenitic, semiaustenitic, or martensitic microstructures and can be hardened by aging at moderately elevated temperatures, 480°C to 620°C (900°F to 1,150°F). The strengthening effect is due to the formation of intermetallic precipitates from elements such

Stainless steels can now be fabricated by the pressing and sintering of wateratomized powder. PM grades embrace: ferritic, austenitic, martensitic, duplex (ferritic + austenitic), dual-phase (ferritic + martensitic), and precipitation hardening (martensitic). Development of dual-phase PM stainless steels reflects the growing need for higher strength, coupled with ductility and toughness. In the present study, a new low-cost PM stainless steel has been developed which combines the advantages of a dual-phase (ferrite + martensite) microstructure with precipitation hardening. Unlike other precipitation-hardening alloys, ductility and impact toughness increase significantly upon aging, notwithstanding attendant increases in hardness and strength. The mechanical properties of the new alloy are evaluated in terms of composition and microstructure.

The award for this technical paper will be presented at PowderMet2009 in Las Vegas, Nevada.

*Manager–Pilot Plants, **Scientist, Research & Development, Hoeganaes Corporation, 1001 Taylors Lane, Cinnaminson, New Jersey 08077-2017; E-mail: [email protected], ***Emeritus Professor, ****Professor, Department of Materials Science & Engineering, LeBow Engineering Building, Drexel University, Philadelphia, Pennsylvania 19104

38

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

Figure 1. Representative microstructures: (a) press-and-sinter PM dual-phase stainless steel; sintered density 7.20 g/cm3 (b) press-and-sinter PM 17-4 PH; sintered density 6.70 g/cm3

as copper or aluminum. Aluminum’s high affinity for nitrogen and oxygen in PM stainless steels necessitates strict atmosphere control during sintering and, for this reason, copper is the most commonly used element for precipitation hardening. These alloys generally have high strength and high apparent hardness while exhibiting superior corrosion resistance compared with martensitic stainless steels. This improved corrosion resistance is derived from the fact that the carbon levels are low and the martensite is formed from additions of nickel and copper. The low-carbon martensite that is formed is weaker but more ductile than the martensite formed in alloys such as SS-410-90HT (carbon bearing), but the strength of these alloys is developed by aging. One of the most common precipitation-hardening stainless steel grades in both the wrought and PM industries is 17-4 PH (Table I). This grade has a martensitic microstructure and its strength and hardness can be improved by aging treatments.4–7 The general corrosion response of this alloy is superior to that of standard martensitic stainless steels due to the higher chromium level. There are many applications in which stainless TABLE I. COMPOSITION OF STAINLESS STEEL PM ALLOYS (w/o) Alloy

C

P

Si

Cr

Ni

Cu

Mn

Mo

17-4PH 409LNi DP2 SS-410-90HT

0.018 0.013 0.015 0.200

0.025 0.01 0.014 0.012

0.85 1.00 0.84 0.81

17.1 11.3 11.6 12.0

4.00 1.30 1.03 0.14

3.55 0.04 0.29 0.01

0.15 0.12 0.10 0.11

0.03 0.25 0.05 0.56 0.22 — 0.05 —

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Cb

steels with only moderate corrosion resistance (compared with 17-4 PH) but excellent mechanical properties are required. A widely used alloy is SS410-90-HT. This is a PM 410L stainless steel in which graphite is added to the atomized powder and the alloy is sintered in a nitrogen-rich atmosphere. When carbon and nitrogen are added to 410L stainless steel, the microstructure becomes martensitic, thereby increasing both strength and hardness. This grade of stainless steel is used in applications where high strength and hardness are required. The disadvantage of using carbon and nitrogen is that they degrade corrosion resistance and also reduce impact strength and ductility. Many PM fabricators select this alloy because there are few alternative compositions. ALLOY DEVELOPMENT The purpose of this work was to develop an alternative composition that makes use of the two strengthening mechanisms. The combination of a dual-phase microstructure and precipitation hardening should allow for the development of a low-cost, high-strength alloy with moderate corrosion resistance. The development of this dualphase precipitation-hardening (DPPH) alloy can improve PM’s competitive advantage over wrought materials. Previous work by the authors focused on developing a dual-phase microstructure in a nominal 12 w/o chromium-containing stainless steel.3 This was accomplished by balancing the ferrite stabilizers (chromium, silicon, and molybdenum) and

39

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

TABLE II. COMPOSITION OF EXPERIMENTAL DPPH ALLOYS (w/o) Alloy

C

P

Si

Cr

Ni

Cu

Mn

Mo

Alloy A Alloy B Alloy C Alloy D Alloy E Alloy F Alloy G Alloy H

0.011 0.015 0.013 0.014 0.017 0.016 0.015 0.016

0.007 0.005 0.012 0 .007 0.010 0.008 0.011 0.012

0.65 0.82 0.83 0.83 0.78 0.73 0.92 0.80

11.81 11.71 12.11 12.65 12.13 12.77 11.82 12.17

1.05 1.22 1.06 0.97 1.05 1.08 1.06 1.07

0.04 0.35 0.99 2.13 2.55 3.06 3.48 3.95

0.10 0.12 0.07 0.05 0.06 0.15 0.08 0.06

0.35 0.31 0.38 0.33 0.35 0.35 0.36 0.34

austenite stabilizers (carbon, nitrogen, nickel, and copper) such that the microstructure consisted of ferrite and martensite (DP2 in Table I). The copper in this alloy was intended only to stabilize the austenite and was at too low a level for any significant precipitation. Therefore, a new set of alloys was made with copper ranging from 1 w/o to 4 w/o. ALLOY PREPARATION AND TESTING The powders used in this study were produced by water atomization with a typical particle-size distribution 100 w/o <150 µm (-100 mesh) and 38 to 48 w/o <45 µm (-325 mesh). All the alloying elements were prealloyed into the melt prior to atomization, unless otherwise noted. The powders were of the same base composition with only the copper content intentionally varied. Table II list the chemistry of the individual heats along with a letter designation indicating a change in copper content. The powders were mixed with 0.75 w/o Acrawax® C lubricant. Samples for transverse rupture (TR) and tensile testing were compacted uniaxially at 690 MPa (50 tsi). All the test pieces were sintered in a high-temperature Abbott continuous-belt furnace at 1,260°C (2,300°F) for 45 min in a hydrogen atmosphere with a dewpoint of -40°C (-40°F), unless otherwise noted. Prior to mechanical testing, green and sintered density, dimensional change (DC), and apparent hardness, were determined on the tensile and TR samples. Five tensile specimens and five TR specimens were tested for each composition. The densities of the green and sintered steels were determined in accordance with MPIF Standard 42. Tensile testing followed MPIF Standard 10 and impact-energy specimens were tested in accordance with MPIF Standard 40. Apparent hardness measurements were conducted on tensile, TR, and impact specimens, following MPIF Standard 43. Rotating-bending-fatigue (RBF) specimens were

40

machined from test blanks pressed at 690 MPa (50 tsi) and sintered at 1,260°C (2,300°F). The dimensions of the test blanks were 12.7 mm × 12.7 mm × 100 mm. RBF tests were performed using rotational speeds in the range of 7,000–8000 rpm at R equal -1 using four fatigue machines simultaneously. Thirty specimens were tested for each alloy composition, utilizing the staircase method to determine the 50% survival limit and the 90% survival limit for 107 cycles (MPIF Standard 56). Metallographic specimens of the test materials were examined by optical microscopy in the polished and etched (glyceregia) conditions. Etched specimens were used for microindentation hardness testing, per MPIF Standard 51. Salt-spray testing on TR bars was performed in accordance with ASTM Standard B 117-03. Five TR bars per alloy (prepared as previously described) were tested. The percent area of the bars covered by red rust was recorded as a function of time. The level of corrosion was documented photographically. RESULTS AND DISCUSSION Development of Dual-Phase Microstructure The compositons of the DPPH alloys were based on the dual-phase chemistry previously developed. This was a nominal 12 w/o Cr-1 w/o Ni-0.35 w/o Mo alloy. For this study the copper was varied up to 4 w/o. Since copper is an austenite stabilizer, it promotes the formation of martensite in the sintered microstructure. For this reason metallography was performed to confirm the level of ferrite and martensite in the final microstructure. This was to determine at what level of copper a dualphase microstructure still existed. Quantitative metallography was performed to measure the actual ferrite content of the PM alloys. Figure 2(a) shows the ferrite level as a function of the copper content. At low copper levels ferrite percentages exceed 40 v/o and at high copper levels the microstructure is predominately martensitic. There is a range of copper levels between 2 w/o and 4 w/o over which the ferrite level is relatively stable at ~30 v/o. In Figure 2(b) the sintered densities of the alloys are shown. Since higher copper levels lead to poor compressibility, the sintered density decreases as the copper level increases, with a dramatic drop-off in sintered density at 4 w/o Cu. For these reasons the study focused on DPPH P/M compositions with copper Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

Figure 2. Sintered properties of DPPH as a function of copper content: (a) v/o ferrite, and (b) sintered density

concentrations <3 w/o. Most of the studies of dual-phase steels have been on wrought low-alloy steels. In these studies the properties of the dual-phase steel have been related to the microstructure in terms of the levels of martensite and ferrite. The tensile strength and other properties have been shown to vary linearly with the volume fraction of the phases by the law of mixtures.8–9 Intuitively, the tensile strength and hardness should increase with the level of martensite, while the ductility and impact toughness should vary proportionally with the level of ferrite. The PM alloys were sintered to a density of 6.60 g/cm3 at temperatures ranging from 1,120°C to 1,260°C (2,050°F to 2,300°F). In this temperature range the alloys are in the two-phase austenite + ferrite region. Upon cooling, the austenite transforms to martensite. By varying the sintering temperature the level of each phase changes. In general, higher sintering temperatures and low copper levels favor the formation of ferrite. Figure 3 shows the mechanical properties as a function of v/o ferrite and the copper level. Similarly to the low-alloy dual-phase wrought steels, as the v/o of ferrite increases the tensile strength and apparent hardness decrease while the ductility (measured by the elongation) increases. For a given v/o ferrite, increasing the copper concentration increases the strength and apparent hardness. This is due to the solutionstrengthening effect of the copper in the matrix. The microindentation hardness measurements in Figure 3(d) support this conclusion with the higher copper contents having the higher microindentation hardness. Table III gives a summary of the mechanical properties of the DPPH alloys.

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Development of Precipitation-Hardening Component Strengthening, as a result of precipitation hardening, takes place in three steps:10 (1) Solution treatment, in which the alloy is heated to a relatively high temperature, allowing any precipitates or alloying elements to form a supersaturated solid solution. Typical solution treatment temperatures are in the range of 982°C to 1,066°C (1,800°F to 1,950°F). (2) Quenching, in which the solution-treated alloy is cooled to create a supersaturated solid solution. The cooling can be achieved using air, water, or oil. In general, the faster the cooling rate the finer the grain size, which can lead to improved mechanical properties. Regardless of the method of cooling, the cooling rate must be sufficiently rapid to create a supersaturated solid solution. (3) Precipitation or age hardening, in which the quenched alloy is heated to an intermediate temperature, or held at room temperature, for a period of time. During aging, the supersaturated solid solution decomposes and the alloying elements form small precipitate clusters. The precipitates hinder the movement of dislocations and consequently the metal resists deformation and becomes harder and stronger. In the DPPH PM alloys copper is the element involved in precipitation. Similarly to 17-4 PH, the DPPH alloys can be aged after sintering to enhance their strength and hardness. Figure 4 shows an aging profile (by temperature) for a range of copper levels in the DPPH PM stainless

41

Previous

1-Page View

2-Page View

Search

Next

Table of Contents

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

Figure 3. Mechanical properties of DPPH PM stainless steel vs. v/o ferrite and copper content. Sintered density = 6.60 g/cm3

TABLE III. MECHANICAL PROPERTIES OF DPPH PM STAINLESS STEELS (AS-SINTERED AND AGED) AISI

42

Impact Energy ft·lb. (J)

Apparent Hardness UTS (HRA) (103 psi) (MPa)

0.20% Offset Yield (103 psi) (MPa)

Elongation (%)

Alloy A Sintered Alloy A Aged

73 76

98 102

52 53

95 95

654 654

69 70

475 482

4.3 6.6

Alloy B Sintered Alloy B Aged

49 54

66 72

53 53

95 96

654 660

70 73

482 502

4.2 6.6

Alloy C Sintered Alloy C Aged

56 56

75 75

51 53

89 100

612 688

69 79

475 544

4.6 7.1

Alloy D Sintered Alloy D Aged

61 69

82 92

52 57

105 121

722 832

81 100

557 688

3.2 5.1

Alloy E Sintered Alloy E Aged

36 40

48 54

58 62

117 142

805 977

95 117

654 805

2.2 4.6

Alloy F Sintered Alloy F Aged

30 36

40 48

54 60

113 137

777 943

87 116

599 798

2.8 3.7

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

Figure 4. Effect of aging temperature and copper content on mechanical properties of DPPH PM stainless steels

alloys. Both the yield strength and apparent hardness behave as expected for an alloy in which precipitation hardening is occurring. As the alloy is heated, precipitates are formed impeding the movement of dislocations causing an increase in strength and apparent hardness. Above 427°C (800°F) the alloy starts to increase in strength and hardness, reaching a maximum in both properties at approximately 538°C (1,000°F). Above this temperature the precipitates start to coarsen and the hardness and strength decrease. The change in ductility of the DPPH alloys is more complicated. A ductility trough occurs in the 2 w/o and 3 w/o Cu alloys at 482°C (900°F), while the ductility of the 1 w/o copper is relatively constant at this temperature. For a given set of proVolume 45, Issue 1, 2009 International Journal of Powder Metallurgy

cessing conditions, as the copper level is increased there will be an increase in the level of martensite in the dual-phase alloy. Since both carbon and nitrogen are ferrite stabilizers, they segregate to the martensite. At low aging temperatures the carbon and nitrogen form carbides and nitrides in the matrix, strengthening the alloys. However, as the aging temperatures are increased, the elements diffuse to grain boundaries and embrittlement occurs. This is the reason for the decrease in elongation at 482°C (900°F). This effect is more pronounced as the martensite level of the alloy increases (1 w/o Cu vs. 3 w/o Cu). Normally the ductility of an alloy decreases as strength and apparent hardness increase. The DPPH alloys are remarkable in that, as the

43

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

strength and hardness increase, the ductility also increases. At 538°C (1,000°F), when the DPPH alloys reach their maximum strength and apparent hardness, the elongation of the alloys increases and in fact exceeds the as-sintered levels, Figure 4. The higher the v/o ferrite in the dual-phase microstructure, the larger the increase in ductility. Comparison of Dual-Phase PrecipitationHardening Alloy with 17-4 PH PM applications mandating strength and hardness with moderate corrosion resistance are limited. Adding carbon (in the form of graphite) to some of the ferritic grades such as SS-410L and SS-430L can provide a martensitic microstructure

with strength and hardness but the alloys are extremely brittle and exhibit poor corrosion resistance due to the formation of chromium carbides. 17-4 PH, a significantly more costly alloy, offers high strength and hardness with excellent corrosion resistance, but with limited ductility. Fıgure 5 shows a mechanical property comparison of 17-4 PH and the 2 w/o Cu DPPH alloy. Despite being a leaner alloy in terms of chromium, nickel, and copper contents, the strength, apparent hardness, and ductility of the DPPH alloy are all superior to the corresponding properties of 17-4 PH. Under identical processing conditions (pressing and sintering) the DPPH alloys, because of their leaner chemistry, achieve a high-

Figure 5. Mechanical properties of DPPH (2 w/o Cu) compared with 17-4 PH

44

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

er sintered density. This is one reason for their superior mechanical properties. One other factor contributing to the superior strength of the DPPH alloys may be the role that phase boundaries play in impeding dislocation motion.11 Not only do dual-phase steels contain boundaries between grains of the same phase but also boundaries between different phases. These boundaries act as barriers to dislocation motion and result in higher work hardening than in a conventional single-phase alloy. These barriers become more effective as the hardness of the two phases differs. The unique feature of this alloy is not only its excellent strength but the fact that, as the strength increases, the ductility also increases. At aging temperatures >482°C (900°F), work hardening occurs because of the formation of copper precipitates in both the martensite and the ferrite, but there is also a tempering of the martensite in the dual-phase structure. The net effect is an increase in both tensile strength and in ducility. To evaluate the corrosion resistance of the 2 w/o Cu DPPH alloy, it was compared with 17-4 PH and SS-410-90HT,12 both high-strength and high-hardness alloys. These three alloys were compacted at 690 MPa (50 tsi) and sintered at 1,260°C (2,300°F) in 100 v/o hydrogen. Saltspray testing, performed according to ASTM Standard B 117-03, was conducted for 240 h. The results are illustrated in Figure 6; this test is intended to serve as a general guide on performance of the alloys. As expected, due to the high carbon content SS-410-90HT performed poorly. The 2 w/o Cu DPPH alloy exhibited moderate corrosion resistance and the highly alloyed 17-4 PH performed the best. Since the mechanism for cor-

rosion varies by application, specific testing must be undertaken to ensure satisfactory performance of the alloy under a given set of conditions. Fatigue tests were performed on PM 17-4 PH and two of the new PM DPPH grades (Alloy D and Alloy F). The results of these tests, in terms of the 90% survival limit, are compared with other PM stainless steel fatigue data by Shah et al. 1 in Figure 10. The latter study compared the fatigue strength of various stainless steels as a function of tensile strength. The 17-4 PH (6.98 g/cm3) exhibited a fatigue strength comparable with that of SS-410L-90-HT. The excellent fatigue response of the two PM DPPH alloys is attributed to their high tensile strength. In general, fatigue-crack propagation rates in PM steels are high and the fatigue limit is dictated by crack initiation rather than crack propagation. Thus, resistance to crack initiation increases as the tensile strength increases. Both the DPPH alloys (D and F) have high tensile strengths and, therefore, high fatigue-endurance limits. It appears that the addition of copper, along with the addition of nickel and molybdenum, leads to harder martensite, which in this case has a positive effect on fatigue strength. CONCLUSIONS • A lean precipitation-hardening grade of stainless steel that utilizes a dual-phase microstructure and copper for precipitation hardening has been developed for applications that require high strength and toughness, but with moderate corrosion resistance. • The DPPH alloys exhibit a unique combination of high strength, high toughness and high fatigue resistance. This is attributed to

Figure 6. Representative appearance of salt-spray specimens: (a) SS-410L-90HT, (b) 2 w/o Cu DPPH, and (c) 17-4 PH. Shown actual size

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

45

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

DEVELOPMENT OF A DUAL-PHASE PRECIPITATION-HARDENING PM STAINLESS STEEL

Figure 7. Fatigue-endurance limit (90% survival) as a function of tensile strength for various PM stainless steels

•

• •

•

their microstructure, which is dual-phase and precipitation hardened. The DPPH alloys exhibit an improvement in ductility with an increase in strength and hardness. The mechanical properties of the DPPH alloys exceed those of 17-4 PH. The salt-spray-corrosion resistance of the DPPH alloys falls between that of SS-410L90HT and 17-4 PH. The DPPH alloys are cost effective when high strength, coupled with moderate corrosion resistance, are mandated.

5.

6.

7.

REFERENCES 1. S.O. Shah, J.R. McMillen, P.K. Samal and L.F. Pease, “Mechanical Properties of High Temperature Sintered P/M 409LE and 409LNi Stainless Steels Utilized in the Manufacturing of Exhaust Flanges and Oxygen Sensor Bosses”, 2003, SAE Paper No. 2003-01-0451. SAE International, Warrendale, PA. 2. P.K. Samal and J.B. Terrell, “Mechanical Properties Improvement of P/M 400 Series Stainless Steel via Nickel Addition”, Advances in Powder Metallurgy and Particulate Materials—1999, compiled by C.L. Rose and M.H. Thibodeau, Metal Powder Industries Federation, Princeton, NJ, 1999, vol. 3, part 9, pp. 15–28. 3. A. Lawley, E. Wagner and C.T. Schade, “Development of a High-Strength Dual-Phase P/M Stainless Steel”, Advances in Powder Metallurgy and Particulate Materials—2005, compiled by C. Ruas and T. Tomlin, Metal Powder Industries Federation, Princeton, NJ, 2005, part 7, pp.78–89. 4. K.A. Green, “PIM 17-4PH Actuator Arm for Aerospace

46

8.

9.

10.

11.

12.

Applications”, Advances in Powder Metallurgy and Particulate Materials—1999, compiled by C.L. Rose and M.H. Thibodeau, Metal Powder Industries Federation, Princeton, NJ, 1999, vol. 5, part 7, pp. 119–130. M.K. Bulger and A.R. Erickson, “Corrosion Resistance of MIM Stainless Steels”, Advances in Powder Metallurgy and Particulate Materials—1994, compiled by A. Neupaver and C. Lall, Metal Powder Industries Federation, Princeton, NJ, 1994, vol. 4, pp. 197–215. J.H. Reinshagen and J.C. Witsberger, “Properties of Precipitation Hardening Stainless Steel Processed by Conventional Powder Metallurgy Techniques”, ibid., vol. 7, pp. 313–323. A. Lawley, R.Doherty, P. Stears and C.T. Schade, “Precipitation Hardening Stainless Steels”, Advances in Powder Metallurgy and Particulate Materials—2006, compiled by W. R. Gasbarre and J.W. von Arx, Metal Powder Industries Federation, Princeton, NJ, 2006, part 7, pp. 141–153. A.K. Jena and C. Chaturvedi, “On the Effect of the Volume Fraction of Martensite on the Tensile Strength of Dualphase Steel,” Materials Science and Engineering, 1988, vol. 100, no.1–2, pp. 1–6. A. Bag, K.K. Ray and E.S. Dwarakadasa, “Influence of Martensite Content and Morphology on Tensile and Impact Properties of High-Martensite Dual Phase Steels”, Metallurgical and Materials Transactions A, 1999, vol. 30A, pp. 1,193–1,202. L.H. Van Vlack, Elements of Materials Science and Engineering, Sixth Edition, 1989, Addison Wesley Publishing Company, Reading, MA, pp. 304–309. E. Werner and H.P. Stuwe “Phase Boundaries as Obstacles to Dislocation Motion”, Materials Science and Engineering, 1984–1985, vol. 68, pp. 175–182. K.J. Irvine, D.J. Crowe, M.A. Cantab and F.B. Pickering, “The Physical Metallurgy of 12% Chromium Steels”, Journal Iron and Steel Institute, 1960, no. 8, pp. 386–405. ijpm

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

HISTORICAL REVIEW

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY Kempton H. Roll*

BACKGROUND A long time ago man discovered he could make a solid piece of metal out of lumps found in the bottom of a fire pit. All he had to do was pound them with a rock and throw them back into a bed of hot coals. The result was a heavy mass of metal that made a far better weapon than a rock. This was the beginning of a new technology that became a “lost art” when new generations of man learned how to melt that metal and simply cast it into whatever shape he wanted. Man re-discovered this “lost art” less than a century ago. By experimenting and communicating his results with others, he advanced it to become a “new technology,” one doing wondrous things for modern man: powder metallurgy (PM). The study, development, and application of machines and techniques for manufacturing and productive processes define a technology. It is the basic core of industrialization. Technologies know no boundaries—political or geographical. Industrialization anywhere in the world is totally dependent on technologies coupled with the skills and resources necessary to utilize them. The professional societies created for the practitioners of technologies, those engaged in experimenting and willing to communicate their results, are one of those resources. APMI is one of those societies. From its humble beginnings fifty years ago as a minor adjunct to a trade association based on a relatively unknown technology, APMI has risen to become an essential component in modern industrialization. Its original focus on the North American continent has now broadened to serve the interests and needs of PM practitioners in industrialized nations all over the world. APMI consists of professionals from all industries that recognize the significance of PM and particulate materials as a modern metalworking process and its impact on a quality-oriented, productivity-minded, cost- and energy-conscious world. This is how it began.

To help celebrate the fiftieth anniversary of the founding of APMI International (originally the American Powder Metallurgy Institute) in 1959, founding Executive Director Kempton H. Roll has put into words why and how APMI was created. Now that it has evolved into the respected international organization it is today, it is appropriate to recognize the tribulations and triumphs behind its creation. This history is not written as a personal memoir nor does it give adequate recognition to the many individuals who deserve credit for their fine contributions to the establishment, acceptance, and growth of this unique international professional society.

WHY AND HOW APMI GOT STARTED Post–World War II emigration to the United States of scholars, scientists, and engineers from war-torn European nations strengthened

*Founding Executive Director, Retired, Beaverdam Run, 38 Ridgeview Drive, Asheville, North Carolina 28804-2754; E-mail: [email protected]

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

47

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

entrepreneurial enterprise in an America busy trying to convert its vast wartime industrial base to a peacetime economy. Its embryonic PM community was one of the beneficiaries of this challenge. The presence of these immigrants in the New World certainly influenced the attitude of Americans toward the need to open more and broader means of communication. One result was the establishment of the Metal Powder Industries Federation, a composite of several new trade associations that had first been organized in 1945 and restructured in 1956. The Federation was already providing, within the PM industry itself, connections between raw material suppliers and finished-product makers but with limited outreach to powder metallurgists and technicians who were providing the operational know-how. The creation of the American Powder Metallurgy Institute was one of the efforts of America’s PM industry to broaden its outreach to these people through its trade association. In the beginning years—postwar ‘40s, ‘50s, and ‘60s—there were two PM worlds: the entrepreneurs who saw in this new technology the opportunity to build a new, hopefully rewarding, business and those who saw opportunities to develop an interesting, if not exciting, career for themselves in a technology just beginning to expand into new markets in the United States. PM offered an alluring opportunity for everyone. For those seeking such a career the greatest challenge was learning as much as possible about the specific details of this new technology that seemed to hold such an enticing potential. It was not that difficult to understand the principles of compacting particles of metal and then fusing them together into a useful metal component utilizing this low-cost, mass-production process. But finding out what was really happening to those particles during this process and exactly how it was being done in practice was extremely difficult. It was obvious that some critical details were being closely guarded by those already in the PM parts-making business. Nor were there college courses being given in PM back then. Earning a Bachelor of Science degree in metallurgical engineering provided minimal, if any, exposure. The metallurgy of compacting and sintering metal powder particles was too irrelevant and too new compared with traditional metalworking. Too few teachers knew enough to teach others. The MPIF trade association, itself a postwar establishment,

48

was still struggling to get the entrepreneurs in the PM parts business to work together toward common goals, market development being the most important. The acceptance of a steel gear made from iron powder instead of one machined from solid steel ran up against the natural skepticism of design engineers and purchasing agents. They already knew about self-lubricating bearings which had been introduced in the late ‘20s but that was porous bronze, not solid steel. BUILDING THE BRIDGE While the MPIF trade association was devoting its time and resources to building a bridge into the future for its enlightened business-owner members, the employees of these companies had to learn the hard way what worked on the manufacturing floor and what could result in a costly error. They needed help beyond that being provided by the metal powder producers, compacting press and sintering furnace manufacturers, and tool and die makers. A small number of consultants did their best to help spread the word about the merits and modus operandi of this new technology but that came at a price and was focused primarily on in-plant production. Technically trained persons—metallurgists and engineers alike engaged in the producing as well as consuming side of a technology-based industry—need to be able to get together and communicate without fear of corporate constraints. It is critical to their careers as well as their ability to accomplish what they are being paid to do. Too often in the early stages of adapting to any new technology their employers—the owners and management of their companies—are extremely reluctant to encourage infor mation exchange. Fortunately, in the PM industry there were other entrepreneurs—the strong and enlightened ones— who saw the benefits of such exchanges. They were willing to risk losing good employee technicians in order to help them gain more useful information about this intriguing technology, and to do it without having to hire a consultant whose knowledge might not be an accurate reflection of what was really happening in such a rapidly changing manufacturing environment. The first attempt to bridge this gap began in 1945 when the Metal Powder Association, predecessor of the Metal Powder Industries Federation, began sponsoring annual conferences. Here the suppliers to the industry could exhibit their prodVolume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

ucts, and powder metallurgists and company technicians were able to meet fellow neophytes struggling to understand what PM was all about. Published proceedings of these events helped preserve and spread the words of wisdom they generated for those unable to participate and for future reference. Unfortunately, yet understandably given the cloak of secrecy surrounding this technology, the presenters of papers published in early proceedings managed to skim over the critical know-how details when it involved actual PM parts-manufacturing techniques. Despite its shortcomings, the technical conference/trade exhibit concept back then was the best, if not the only, way to learn what was going on in the new PM industry. Beyond encouraging everyone in the industry to learn more about their future prospects by sponsoring and promoting attendance at technical conferences and trade shows, MPIF alone could do little more without creating conflicts of interest. The Federation had to focus its attention and resources on serving the best long-term interests of its corporate-member companies, not their employees. An obvious solution was to create an organization whose members were individuals, not corporate entities. And why not operate both under the auspices of one headquarters staff? It would not only be less costly but also offer an ideal way to coordinate areas of common interest so that all facets of the PM industry could speak with one strong, powerful voice to the rest of the metalworking world. CREATING THE AMERICAN POWDER METALLURGY INSTITUTE Operating a professional society for individuals within the framework of a trade association already established for the purpose of representing corporate management was, and still is, rare indeed. It is either one or the other. Either a trade association for the management personnel of companies representing an industry or a professional society for individuals involved in that industry’s technology. Living together under the same management roof requires two different styles of operation. Even the Inter nal Revenue Service recognizes the distinction between them: 501(c) 3 for the tax-exempt professional society vs. 501 (c) 6 for the tax-exempt trade association. When one precedes the other, and with both having an established staff and headquarters, arranging a Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

mutual management marriage is difficult to achieve. Invasion of one another’s turf, each competing for funding from the same sources and neither having complete control over responsibility for taking action can be debilitating, wasteful, and frustrating for any industry and certainly for the association executives trying to manage such a conglomeration. However, there seemed to be no reason why the still young, not-too-entrenched PM industry and its trade association could not coexist with its own professional society and manage it with the same staff. After all, the staff would be dealing with the same companies, only at different levels of authority and responsibility. No marriage vows necessary: just a newborn baby and its proud but powerful parent. MPIF’s newly hired executive director, Kempton H. Roll, was a member of, and well acquainted with, the professional societies for metals, the American Institute of Mining, Metallurgical and Petroleum Engineers, (AIME) and the American Society for Metals (ASM). He also belonged to the Society of Automotive Engineers (SAE) to stay abreast of the auto industry’s involvement with PM. He knew that they each had to reach out to companies in the metals industry to help support them with contributions but that their main financial resource came from the individual members. He saw no reason why the Federation could not do the opposite: start with the trade association and its corporate members and simply establish an adjunct professional society for individual members. Membership would be open to everyone in the industry: no special qualifications required, just the ability to pay nominal dues. This would provide an ideal connection for those who needed a way to keep in touch with others working in the PM field including those working for companies whose management had not yet seen fit to join the Federation, thus depriving them of a useful information source. In retrospect, these intentions, so noble and high-minded, were far from the thinking of the Federation’s executive director in 1959. The founding of the American Powder Metallurgy Institute was motivated at the outset by none of the above. It was simply based on the need to broaden and expand the market for MPIF’s activities. An organization for individuals would provide a captive market for MPIF to promote Federationsponsored conferences and trade shows and those

49

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

same individuals would be buying its books, standards, and conference proceedings. HOW APMI GOT ITS NAME Kempton Roll felt it should be known as an institute rather than a society. There were too many of the latter and the name did not sound as professional to him as institute. AIME was an institute. ASM was a society. Membership in AIME was a privilege and respected by professional engineers. Belonging to ASM got you into the Metals Show and a subscription to Metal Progress magazine. American was included because he knew, at least at that time, that anything American was of interest to overseas engineers who wanted to learn more about what Americans were doing to expand industrialization of this technology. In those days, the word American gained respect. Right from the start overseas powder metallurgists, engineers, technicians, educators, and equipment and raw material suppliers joined in large numbers and became a strong part of the Institute. He deliberately decided not to recommend designating APMI’s local groups chapters because ASM used that designation. Sections seemed the more appropriate alternative. Later, however, the term chapters was applied so, for the purpose of this article, they will be referred to as chapters. The Federation’s Board of Governors, chaired by George A. Roberts, whose judgment was respected by everyone in the PM industry and considered without prejudice, concurred with his proposal to create a professional society with the name American Powder Metallurgy Institute. The Board of Governors approved unanimously. Legal counsel saw no problems. It was a win-win situation for everyone. That’s why and how the American Powder Metallurgy Institute, now more appropriately designated APMI International, became an integral, yet independent, part of the MPIF trade association operation. EARLY GOVERNANCE At first the Institute was governed by the Federation’s Board of Governors, consisting of the president of each association, the Federation president, and the executive director, to which was added the APMI president. He was appointed, not elected; the selection was based on consultation with its Institute’s executive director who also

50

served the Federation in that capacity. It was a no-hassle arrangement. The first appointed president of the new APMI was a member named Roy E. Blue. He accepted what was then perhaps a dubious honor with the understanding that he would not have to attend any meetings, answer letters, or do anything that would interfere with his responsibilities as the Chrysler Corporation’s Chief Engineer who was responsible for the application of PM products in Chrysler automobiles. He did not report to Andy Langhammer, the powerful, strong-willed, innovative president of its Amplex Division, which made PM parts for Chrysler as well as other companies willing to buy them. Amplex refused to join the Federation but the door had been opened by enlisting support for the Federation’s efforts through individuals like Roy Blue who became members of the Institute. Roy and the executive director got along well sharing their dedication to the advancement of PM technology and its application, regardless of who made the parts. He served as president from 1959 through 1962. During those first three years he succeeded in avoiding every meeting of the Board of Governors, knowing his views were being presented in absentia by the executive director. George G. Karian succeeded Roy Blue for the next two years. In contrast, he never failed to attend board meetings. George played a strong role in initiating publication of the International Journal of Powder Metallurgy and promoting its acceptance. He also championed, by example, the role that golf tournaments could play in encouraging local chapter membership. From then on APMI presidents played active roles in the growth and governance of the Institute. Starting in 1987, APMI established its own board of directors with the executive director, his staff, and legal counsel continuing to serve in their customary capacity. THE ORIGIN OF LOCAL CHAPTERS In the ‘60s the number of companies involved with some aspects of the PM industry, in-plant as well as those making parts for customers in their area, began to expand. Automobile manufacturers, the largest users of PM parts, were centered in Detroit. Philadelphia was focused on metal powder production and equipment manufacture. New York was the heart of the business world. Sequestered in the mountain region of Western Pennsylvania, St. Marys was home to the greatest Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

concentration of custom PM parts makers anywhere in the United States. To a far lesser extent, Chicago had a large number as well. The West Coast area surrounding Los Angeles began to emerge as a center of PM, spurred by the pioneering spirit of its business owners and their isolation from the rest of America’s industrialized regions. New England, in response to the declining textile industry, was rapidly adapting its manufacturing skills to this new technology. Innovative metal workers and machine-tool manufacturers in Connecticut and Massachusetts spawned many PM parts makers, both custom, those selling parts on the open market, and inplant, those producing parts for themselves. While Institute members provided a support base for the technical conference and trade show events sponsored each spring by the Federation, it was becoming obvious that there was a growing need for some way to enable PM-oriented individuals to congregate more than once every twelve months. In Chicago, Detroit, Los Angeles, New York, and Philadelphia, individuals sharing a common interest in PM were already getting together informally—some spontaneously, some deliberately. Now was clearly the time for the Federation to either do something locally for the individuals working in the PM industry or not do anything but serve the interests of its trade association members. In the ‘50s, it was traditional for professional societies to hold monthly dinner meetings. Before APMI, those working in the PM industry had the choice of two well-established ones serving the metals industry at that time: AIME and ASM. The executive director of MPIF and now of APMI, a metallurgical engineer himself with degrees from Yale University and the Polytechnic Institute of Brooklyn, had belonged to both since graduation and regularly attended their local chapter meetings in New York City. In fact, he often gave talks there about PM as well as at their chapters in other cities. PM was still relatively new and unknown at that time so the idea of encouraging local PM groups to meet every month in order to get to know one another, establish contacts with customers, and try to ferret out tidbits of technical know-how made good sense. Nor could the added incentive of a night out with the "boys" be ignored (there were no female metallurgists in those days). The behind-the-scenes story about the foundVolume 45, Issue 1, 2009 International Journal of Powder Metallurgy

ing of some APMI chapters deserves noting on the occasion of this 50th anniversary. For instance, there is an explanation as to why it took so long— seven months—before the New York Chapter was officially established. (One would think it should have been the first, considering its proximity to the new Institute’s headquarters.) Members of AIME’s New York chapter, mostly metallurgists, held a dinner meeting each month at a local restaurant. So did ASM at a different time and location. These meetings offered those working in the metals industry or in any way associated with it an opportunity to get together and relax over pre-dinner cocktails often provided by a supplier to the metals industry. It was a popular, if not essential, means for anyone whose career involved metallurgy to keep up with what was currently happening. Besides attending these technical society-sponsored dinner meetings, powder metallurgists and anyone else interested in the PM industry realized shortly before the creation of APMI that this technology was evolving rapidly. Some started getting together after work, usually at a restaurant for cocktails and dinner followed by a guest speaker. For those working in the New York City area it became known as the Hob Nob Club after the name of the restaurant where they met. All the local PM companies, spearheaded by the powder producers, were participating. So were MPIF’s executive director and his assistant, Peter K. Johnson. As soon as APMI was officially established, one of its first objectives was to convince the Hob Nobbers to affiliate themselves as the organization’s first local chapter. But it was a greater challenge than anticipated because AIME, also headquartered in New York City, had already established a Powder Metallurgy Committee headed up by an APMI member employed by a company belonging to the Federation. The Committee’s purpose was to hold independent AIME-sponsored dinner meetings devoted exclusively to PM. Meanwhile, primarily because APMI’s staff and office facilities would take care of printing and mailing meeting notices, etc., at no cost to its participants, the Hob Nob group had been persuaded to become the nucleus of an APMI New York chapter, effective November 13, 1960. This made it much easier to convince AIME’s Powder Metallurgy Committee to abort and instead affiliate themselves with the new APMI group.

51

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

In the interim, while all this political maneuvering was going on at headquarters, Chicago and Philadelphia managed to beat New York out of the #1 spot as the first “charter founder” of a local APMI chapter. It began with Philadelphia, an area that included Hoeganaes, America’s largest iron powder producer, as well as leading press manufacturers F.J. Stokes and Baldwin-Lima-Hamilton and a major sintering furnace maker, the Drever Company. Persons in that area involved with PM had already established an independent local group, a move initiated by a Hoeganaes’ sales manager as an effective marketing strategy. They held their first dinner meetings in the heart of Philadelphia at the historic Engineers’ Club founded by Ben Franklin. They agreed to affiliate themselves with APMI on March 31, 1960. Later they moved their meetings to the outskirts of the city to make attending more convenient for those driving in from the environs. Meanwhile, the Hoeganaes sales representative in the Chicago area, following the lead of his company’s marketing strategy, quickly organized a group of interested PM people to meet monthly. When he learned that the Philadelphia people were going to affiliate themselves with APMI, he managed to beat them to it by one week. That’s how Chicago became the first local chapter to be officially chartered in the American Powder Metallurgy Institute. The date was March 24, 1960. The greatest challenge to the new Institute and its executive director was a group that preexisted APMI: the Detroit Powder Metallurgy Society. This was when Detroit was the heart of the automotive PM parts industry. Copper powder was the primary raw material, not iron. Ford had a big inplant facility in Dearborn. Amplex was perhaps the largest PM custom parts maker at the time, serving Chrysler Corporation’s needs as well as any other companies using self-lubricating bearings. Most of the tool and die makers were also in the area. The Society’s founding had been inspired years before the creation of APMI by the local sales representatives of equipment manufacturers and powder producers in collaboration with powder metallurgists working in that area. Their primary inspiration came from Amplex and Ford personnel who had no objections to being wined and dined by sales representatives anxious to accommodate them. With the exception of Amplex, most companies

52

supporting the Detroit Society were corporate members of the Metal Powder Industries Federation. But the only one headquartered there was Greenback Industries, a copper powder producer headed up by a dynamic ex-bond salesman, Earl Lowe, who deliberately established in a Detroit suburb their storefront corporate headquarters, sales office, and a test laboratory, including a staff powder metallurgist. Persuading the Society to give up its independence and become the Detroit Chapter of APMI was difficult. Its members saw little benefit to be gained from a headquarters organization located in New York City. They had already established the tradition of monthly meetings at the Chop House where they would be entertained and otherwise spoiled by all of the powder producers’ sales representatives serving that area. PM equipment makers and certainly the local tool and die makers also did their share of entertaining their customers on these occasions. It was only when Greenback Industries’ powder metallurgist, Joe Farmer, was elected to the Society’s governing body that APMI’s executive director was able to persuade the group to become its Detroit Chapter (now the Michigan Chapter) on April 21, 1960. Again, the primary lure was the offer to fund their operational expenses with a dues rebate; the same “carrot” that had been dangled before each of the previous independent organizations devoted exclusively to PM-oriented people. Other chapters were soon established wherever there was a concentration of interest in or involvement with the rapidly expanding PM industry. The first West Coast chapter was established in the Anaheim, California, area where Kwikset was operating a large in-plant PM facility. The date was October 5, 1960. Later the San Francisco area began expanding its PM connections with parts makers in Oakland and other PM interests in Silicon Valley. Eventually companies up in the State of Washington and as far away as Colorado Springs were embraced by the West Coast Chapter. The powers of persistent yet gentle persuasion combined with the fact that almost all of the companies involved belonged to MPIF and, perhaps most compelling, that the costs of operating the chapter would be borne by the new Institute via a rebate from members’ dues (coupled with the benefits of their connection with the MPIF headquarters staff, reduced registration fees at spring Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

technical conferences and trade shows, etc.) led to the growing number of APMI’s local chapters. During its first 50 years of existence, the American Powder Metallurgy Institute established eighteen chapters. Consolidations reduced that number to thirteen, largely reflecting shifts in PM industry concentrations. The New York Chapter closed; its members, scattered between Philadelphia and Connecticut, had little interest in coming to New York City for a dinner meeting. Easton was folded into Philadelphia. Northern California merged back into the West Coast Chapter after five years of independence. Detroit expanded to become the Michigan Chapter. PennYork, based largely on one company in Towanda, Pennsylvania, closed when that company shifted its PM operations elsewhere. The latest addition was the founding of the Mexico Chapter in 2004, a reflection of the globalization of the PM industry and broadening of APMI International’s importance to PM industry employees located in any of North America’s industrialized nations. Following are the official founding dates recorded at APMI International headquarters for each local chapter since its creation in 1959: 1. Chicago March 24, 1960 2. Philadelphia March 31, 1960 3. Detroit April 21, 1960 4. West Penn June 2, 1960 5. West Coast October 5, 1960 6. New York November 30, 1960 7. Cleveland March 20, 1961 8. Penn-York April 17, 1961 9. Dayton May 18, 1961 10. Indiana October 22, 1962 11. Boston March 27, 1963 12. N. California February 16, 1965 13. Hartford September 29, 1966 14. Easton January 30, 1967 15. Canadian January 23, 1969 16. Pittsburgh April 6, 1970 17. Southeast May 9, 1985 18. Mexico August 23, 2004 THE INTERNATIONAL JOURNAL OF POWDER METALLURGY Besides being an obvious APMI membership benefit (AIME had its Journal of Metals and ASM its Metal Progress), the same motivating force for founding the Institute—promoting the broadening and acceptance of powder metallurgy technology—resulted in the decision to initiate publication Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

of a journal devoted exclusively to PM. It could not be perceived as a magazine that would put the Federation in conflict with its associate members in the publishing world, Precision Metal Molding and Materials & Methods. It had to be more like a professional journal that would depend on voluntary submission of technical papers and not on articles written by a salaried editorial staff. Adding international to its title broadened its potential readership base which, hopefully, would attract submissions by overseas authors who were less inhibited than domestic ones when it came to revealing technical processing details. Publishing more frequently than quarterly was out of the question: not enough funding and definitely not enough worthwhile material, at least from American sources due to the processsecrecy syndrome. The powder producers and equipment makers were perfectly willing to write about PM parts manufacturing techniques but could not risk alienating their PM parts-maker customers. PM was then, and doubtless still is, a very competitive business. The most compelling motivation for launching the Journal was the awareness that if APMI did not do this, someone else would. The Metal Powder Report published in England by W.D. Jones was already underway. Dr. Henry H. Hausner, a well-respected PM consultant, was also editing an English-language PM publication for Paul Schwarzkopf and his company, Metallwerk Plansee. The challenge in this instance was persuading Henry Hausner, a friend and former professor of the executive director at Brooklyn Polytechnic Institute, to serve as the editor-in-chief of a new international journal devoted exclusively to all aspects of the PM industry. For this he would be paid a stipend and have his name prominently displayed on its masthead as Editor-in-Chief. The latter was a significant inducement to someone who earned his living as a consultant. Henry and his secretary, Helen Friedemann, accepted the offer and, with Peter Johnson’s close support and involvement on our staff as its Business Manager, they made the new PM publication into the highly respected, very professional international Journal it still is today. Volume 1, Number 1, of the Inter national Journal of Powder Metallurgy was issued in the Fall of 1965. Kempton Roll was listed as Publisher, Henry as Editor -in-Chief, Helen as

53

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

Associate Editor, and Peter Johnson as Business Manager. Also listed were Earl Lowe, MPIF president; Jerome Kuzmick, APMI president; and George Karian, APMI past-president. George’s name was included in the masthead as a way of acknowledging his strong role in creating the Journal. An Editorial Advisory Committee had been appointed comprising the best-known international powder metallurgists at the time representing Argentina, Austria, Canada, Finland, France, Germany (D.D.R. and D.B.R.), India, Italy, Japan, Netherlands, Poland, Sweden, Switzerland, the UK, and the U.S. The Journal projected an impressive image of America’s young PM industry and helped strengthen its emerging role in the global PM community. Now in its 45th year of publication, the Journal has gone through several iterations. Henry continued to serve as its Editor-in-Chief long after MPIF/APMI moved its headquarters from New York City to Princeton, New Jersey, in 1973. He commuted by train from his residence on Long Island to his desk at the Institute’s new headquarters in Princeton until his decision to retire and return to his native Austria. His responsibili-

ties as Editor-in-Chief—as well as his desk at Princeton headquarters—were taken over by Alan Lawley, FAPMI, Emeritus Professor at Philadelphia’s Drexel University. As well known and respected in the international PM community as was Henry, Alan expanded the scope of the Journal to include all particulate materials and added an Inter national Editorial Review Committee. The familiar name of Peter K. Johnson, now semi-retired, remains on the masthead as a Contributing Editor, his original business management responsibilities now handled by James P. Adams, as Managing Director. THE ORIGIN OF WHO’S WHO IN PM Most small societies and local clubs issue a printed roster of members’ names and addresses plus other useful information. The larger professional ones seldom do: too costly to print and distribute. The roster usually bears the mundane title of “directory.” There were none that even came close to being considered a Who’s Who, a designation based on the title of a book, Who’s Who in Engineering, that provided biographical details about “carefully selected, professionally

The cover and masthead of the first issue of the International Journal of Powder Metallurgy published in 1965 by the American Powder Metallurgy Institute

54

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

significant” individuals engaged in any field of engineering. No society membership directories had ever been issued using the “Who’s Who” designation. That name came to mind when the young MPIF executive director found his name listed in the Who’s Who book the year following his purchase of an edition for reference purposes. He realized it was his purchase that prompted his name being included in so coveted a publication, not his “professional significance” as an engineer nor any notable contributions of his to the engineering profession! It was very close to being a sales gimmick. APMI had grown to the point where it needed a directory identifying its members. The name directory sounded too ordinary to the executive director. A more impressive title was needed, if only to help bolster the image of the new Institute. The un-copyrighted Who’s Who title seemed to him to be an appropriate designation for an APMI membership directory, if only to attract new members seeking peer recognition. More than a roster of members, he envisioned it also serving as an effective advertising medium for members of the Federation’s associations looking for ways to market their products and services to the PM industry. Advertising also offered a painless way to fund its publication and distribution. The first Who’s Who in PM was published in 1963, thanks to the advertising support provided by the Federation’s member companies selling to the industry. In later years, the Who’s Who connotation enhanced its value to members by also becoming an excellent place for recognizing individuals serving on governing boards: a subtle way to encourage members to contribute their time and talents in governing the industry’s trade associations. It has since become especially appropriate for listing the recipients of honors and awards bestowed by MPIF and APMI. Such listings of all those recognized by the PM industry for their service and dedication provides a permanent record of their notable achievements as well as becoming an invaluable historic reference source. Over time, Who’s Who in PM has become an indispensable asset to everyone involved with the PM industry anywhere in the industrialized world. Updated annually, it is a handy reference source for locating and identifying every individual and company having any connection with PM by virtue of being a member of APMI International or Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

the Metal Powder Industries Federation. It serves the interests of both the Federation and its trade association members as well as the worldwide community of individual APMI International members and their local chapters. In recent years it has also offered details about the headquarters staff of both APMI and MPIF and their areas of responsibility: now one can actually get to know and speak with a real person when seeking help or information. There is no doubt that the benefits of APMI’s Who’s Who in PM far exceed those offered by the Who’s Who in Engineering that inspired its name. WHAT WILL THE FUTURE HOLD? It has already become obvious in this rapidly changing world that science and technology will continue to play an ever-increasing role in the advancement of civilization. Those whose intellectual energies and talents embrace PM and particulate materials technology are destined to provide inspiration and, often, the means to achieve yetunknown goals vital to this advancement: • The increasing awareness of the significance of nanotechnology—smaller and smaller particles of metals and non-metallics—will foster mankind’s ability to create new materials with properties and applications unheard of, or even unimagined. • Working with finer, purer particles of matter, PM will surely play a significant role in the “greening” of our planet and relieving our dependence on non-renewable energy sources. • PM is now well entrenched globally at the leading edges of tomorrow’s technologies seeking paths to goals that lie ahead. MPIF and APMI International working in close collaboration with other such organizations located throughout today’s industrialized world will continue to play a vital, dynamic role in realizing the glowing future of mankind’s place on planet Earth. • The continuing role of APMI International in the metalworking world will be changing to reflect what has already begun to take place. Like the powerful, irrevocable impact that globalization has had on the world’s PM industry, the efficiency coupled with multiplicity of means for conducting business— global or otherwise—and the rapidity with which essential information can be conveyed

55

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

THE ORIGIN AND ROLE OF APMI INTERNATIONAL IN NORTH AMERICA’S PM INDUSTRY

will soon render obsolete the original motivation for local chapter meetings. The shift will be from verbal communication (abetted by libation or not) to an overwhelming array of visuals combined with swift, no-nonsense electronic voiceovers and text-messaging. The advent of the Internet no doubt contributes greatly to this impersonal connection. No martinis, wine, or beer to humanize the transactions. Or so it seems. • The demands of space technology will generate increasing awareness of the advantages PM offers as a most effective, energy-efficient method for creating metal and particulate

56

materials components on site elsewhere in our universe beyond the boundaries of planet Earth. There can be no doubt that PM and particulate materials technology has just begun to scratch the surfaces concealing what lies ahead. The ancient art that saw its origins before mankind discovered how to melt metals has evolved into an indispensable tool for achieving mankind’s goals. As Minerva, the Roman Goddess of Wisdom, is credited with saying, “ad astra per aspera”: “to the stars through hardships.” Let those in the PM world continue doing the same. ijpm

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Search

Table of Contents

Next

57

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 WEB SITE DIRECTORY EQUIPMENT MANUFACTURERS ABBOTT FURNACE COMPANY www.abbottfurnace.com Abbott Furnace Company specializes in continuous furnace technology for sintering, steam treating, heat treating, annealing, tempering and brazing. Technical innovations include Ceramic Muffles and Belts, Advanced VariCool System, Quality Delube Process and Computerized Controls. Abbott also offers custom fabrication of replacement parts, a full line of spare parts and repair and calibration service. ABTEX CORPORATION www.abtex.com Abtex Corporation is a single-source manufacturer for abrasive deburring brushes and the machines needed to apply them. Brush line additions include 6” a composite hub radial wheels in one-half and one inch widths. Supplementing its end deburring machines, the deburring systems group now offers both wet and dry process planetary head flow-through systems for flat parts, and rotary indexing systems for addressing more complex part geometries. ALLOY ENGINEERING COMPANY www.alloyengineering.com Since 1943, The Alloy Engineering Company has been recognized as the premier designer and manufacturer of high-quality, alloy equipment for furnace and high-temperature corrosive industrial applications. Our heritage of design and manufacturing innovation is as important as our commitment to sharing our application expertise with customers and providing responsive technical support of products throughout their operational life. We believe that customers satisfaction defines quality, And, delivering, or surpassing, expected performance and life is essence of customer satisfaction. BRONSON & BRATTON INC. www.brons.com We are designers and fabricators of PM Tooling Design: your part, your press, our finished design Engineering: our experience, our CAD, equals totally integrated tooling Technology: our computer database

58

with design variations will conform to your equipment requirements Processing: our CAM system integrates the engineering and machine data required for quality tools Quality: has been a tradition at Bronson & Bratton since 1948. We are ISO 9001:2000 Certified CAD + CAM = CIT (Computer Integrated Tooling) CENTORR VACUUM INDUSTRIES INC. www.centorr.com CVI is a 50-year-old manufacturer of custom high-temperature vacuum and controlled-atmosphere heat-treat and sintering furnaces for the Metals and Ceramics industries. Applications include heat treating, brazing, sintering, hot pressing, diffusion bonding, and injection molding of metals or ceramics. Furnaces are available with either refractory metal or graphite hot zones in sizes from 1 cu. in. to several cu. meters, from 1,000°C to 3,000°C. CIECO, INC. www.ciecocontrols.com CIECO offers five levels of press controls for the powder metal industry. From low-cost PPC1100R to the Automator II controller. Our dual microprocessor controls eliminate the high cost of dual plc packages and comply with OSHA, ANSI and CSA safety standards. Visit our Web site at www.ciecocontrols.com to view these controls. For an Internet Webinar demonstration on the Automator II controller, call our customer service department at 412-262-5581. C.I. HAYES, A GASBARRE PRODUCTS COMPANY www.cihayes.com For the past 103 years, C.I. Hayes has manufactured industrial furnaces and generators for many industrial applications. The furnace line includes high-temperature pusher furnaces, single-chamber and continuous vacuum furnaces with air or oil quench capabilities, tube strip furnaces, and conventional continuous mesh belt furnaces for sintering, steam treating, delubing. Endothermic, exothermic, and dissociated ammonia generators are manufactured in various sizes. Custom-designed furnaces are manufactured for specific parts and processes.

CM FURNACES, INC. www.cmfurnaces.com Furnaces & Equipment: Furnaces operating at temperatures from 1,200°F to 4,000°F. Batch and continuous pusher furnaces from lab scales to fully automated production units. All electric with high-efficiency insulation packages. Atmospheres: Furnaces available to operate in hydrogen, nitrogen, inert or air atmospheres. Continuous dew point and oxygen-level monitoring and control are offered. Other Products/Services: In-line delube and debind ovens with air, inert and/or reducing atmospheres. Debind ovens for BASF binder system. Toll firing and process development. ELMCO ENGINEERING, INC. www.elmco-press.com ELMCO Engineering Inc. is a leading manufacturer of new and rebuilt PM equipment. We service all makes of presses, provide control and feeder upgrades, and have an extensive parts inventory at three locations. We offer our own new ELMCO multimotion mechanical presses, and standard molding mechanical presses, hydraulic specialty presses, plus inclined and upright mechanical sizing presses. As Yoshizuka’s North American representative, we offer a full line of compacting presses, including state-of-the-art CNC hydraulic servo models. ELNIK SYSTEMS, DIV. OF PVA MIMTECH, LLC www.elnik.com ONE SOURCE Debinding & Sintering Equipment for MIM Catalytic Debinding Oven Model CD3045 is designed exclusively for catalytic debinding of parts made from BASF Catamold feedstock. Solvent Debinding System Model SD3045 is designed for wax-based feedstocks. ELNIK’s MIM 3000 Sintering Furnaces process any metal with any binder in a “ONE STEP” debinding and sintering cycle without having to move the parts. Laminar gas flow guarantees uniformity during debinding and sintering. AccuTemp assures that the sintering temperature is within ± 1°C of the actual temperature.

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 WEB SITE DIRECTORY

FETTE COMPACTING www.fetteamerica.com FETTE GmbH, the world leader in tablet press technology, also offers a range of high-precision hydraulic presses for the manufacturing of carbide cutting inserts. These systems can be provided complete with Pickand-Place robots for off-loading and the touch-screen control system includes advanced data-acquisition capabilities. Our Web site is: www.fette.com GASBARRE PRODUCTS, INC. www.gasbarre.com Provides full-service design, manufacturing and marketing of capital equipment for the particulate materials and thermal processing industries. Featuring Gasbarre Mechanical Presses, Best Hydraulic Presses, PTXPentronix High Speed Presses and Part Loaders, SIMAC Isostatic Presses, Sinterite Furnaces, C.I. Hayes Furnaces, McKee Carbide Tooling and related services. Gasbarre supplies all processing equipment for the PM industry, from atmosphere generators to powderhandling equipment, presses, sintering & annealing furnaces, sizing presses and oil-impregnation equipment. HERNON MANUFACTURING INC. www.hernonmfg.com Since 1978, Hernon Manufacturing has produced high-performance impregnation resins and processing equipment. Hernon Impregnation Resin (HPS™) offers a breakthrough in sealing leaking porous metals such as powder metal castings and sintered metal parts. HPS™ also offers other benefits such as increased lubricity, which lowers tool wear, and resistance to degradation by hydrocarbon solvents such as gasoline, motor oil, and transmission fluid. Hernon Manufacturing provides complete impregnation systems including design and installation. HOLROYD EDGETEK www.holroyd.com For over a century Holroyd has been a builder of precision machine tools for the manufacturing of high-precision gears, worms, worm wheels and rotors. For the powdered metal industry Holroyd also produces the line of Edgetek Superabrasive Machining

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

and Turning Systems. The Edgetek process has been effective for removing difficult-to-machine materials, interrupted cuts, and high metalremoval rates for powdered metals and sinter-hardened powdered metals. Additionally a substantial increase in tool life over conventional machining methods will result in lower cost per part. MINOX/ELCAN INC. www.minox-elcan.com Minox/Elcan works with customers to provide high-performance screening solutions for their advanced powdered metal products. Our technology offers significant advantages over any other screening machines. These performance advantages can be demonstrated on production-sized equipment in our full-scale testing/tolling facility. At our facility in Mamaroneck, NY, we provide production solutions for many leading powdered metals companies. Come see why we have the best screening machines! OSTERWALDER, INC. www.osterwalder.com OSTERWALDER AG develops and manufactures state-of-the-art hydraulic and mechanical-hydraulic powder presses. The wide product range offers system solutions for pressing iron, ceramic, tungsten carbide powders and other materials to small precision parts or sophisticated structural parts of first-class quality. OSTERWALDER AG provides a useroriented press technology exceeding today's requirements. SELEE CORPORATION www.selee.com SELEE Corporation, a member of the Porvair Group, manufactures hightemperature, low-mass kiln furniture in seven different ceramic compositions to meet your application’s specific needs. We make both open-cell foam kiln furniture as well as microporous kiln furniture. We are also a distributor for Ferro Process Temperature Control Rings. Our manufacturing facility is located in the beautiful Blue Ridge Mountains in Hendersonville, North Carolina, U.S.A. Certified ISO 9001:2000 and ISO 4001:2004.

SMS MEER GMBH www.sms-meer.com SMS Meer GmbH is part of the SMS group and is located at Mönchengladbach, Germany. The hydraulic press division offers forging and powder compaction presses. We are over 50 years a competent partner for the metal powder, ceramics and tungsten carbide industry and have sold more than 1,800 pf powder presses. Range of powder presses and adapters: - Hydraulic CNC presses from 600 up to 20,000 kN - Hybrid CNC up to 2,500 kN - High-speed mechanical presses from 30 up to 450 kN - Controlled punch adapters (CPA) with up to eight integrated CNC press axes

METAL POWDER PRODUCERS ACUPOWDER INTERNATIONAL, LLC www.acupowder.com ACuPowder, with plants in NJ & TN, is a major U.S. producer of metal powders. Products include: antimony, bismuth, brass, bronze, bronze premixes, chromium, copper, copper oxide, copper premixes, diluted bronze premixes, graphite, highstrength bronze, infiltrant, manganese, MnS+, nickel, phos copper, silicon, silver, tin, tin alloys and PM lubricants. New products include powders for MIM, thermal management. "Green Bullets," lead-free solders, copper brazing, plastic fillers and cold casting. AMETEK SPECIALTY METAL PRODUCTS www.ametekmetals.com Major producer of stainless steel and high-alloy powders for PM, filtration, MIM, and thermal spray. Fully dense consolidation capability via proprietary pneumatic isostatic forging (PIF) process to make bars, rods, and specialty shapes from a wide variety of alloys. Full range of thermal management products like AlSiC, coppertungsten, copper-molybdenum, and copper clad-copper/molybdenum copper heat sink for telecommunication, advanced radar systems, and

59

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 WEB SITE DIRECTORY

other high-heat-dissipation requirements. U. S. manufacturer of CP Ti and Ti 6/4 powders through our Reading Alloys operation. ARC METALS CORP. www.arcmetals.com ARC Metals is the industry leader in the production of remill materials. ARC Metals also offers custom blending and full metallography with in house technical support. ASBURY GRAPHITE MILLS, INC. www.asbury.com Asbury Graphite Mills, Inc., and its Southwestern Graphite Division continue to be the world leader in supply of quality and consistency of graphite and carbon powders for admix applications. Since the inception of the powdered metal industry, Asbury has been providing both natural and synthetic graphite products for every application. Asbury also offers graphite-based lubricants and sintering trays to the industry. For strength and dimensional stability, choose Asbury. HENGYUAN METAL & ALLOY POWDERS LTD. www.hengyuanpowders.com Hengyuan Metal & Alloy Powders Limited (www.hengyuanpowders.com) supplies a variety of fine metal and alloy powders for PM and MIM applications. Ferroalloy powders such as Ferro-molybdenum, low-carbon ferromanganese, high-carbon ferro-manganese, low-carbon ferro-chromium, high-carbon ferro chromium, ferrophosphorus, ferro-tungsten, ferroboron, ferro-titanium, chromium metal powder, copper and copperalloy powders, stainless steel powders. Contact elleny@hengyuan powders.com. Phone 416-997-8780. HOEGANAES CORPORATION www.hoeganaes.com Hoeganaes Corporation, world leader in ferrous powder production, has been a driving force within the PM industry for 55 years. The company has seven manufacturing facilities in the USA and Europe to meet customers' needs worldwide. It continues to invest in manufacturing capacity to support industry growth while providing design, process and material system education worldwide. Hoeganaes holds these certifications: ISO 14001, ISO/TS 16949, and ISO 9001, QS 9000.

60

MAGNESIUM ELEKTRON POWDERS www.magnesium-elektron.com Magnesium Elektron Powders, a world leader in the manufacture of magnesium particulates and specialty niche alloy powders. At our three facilities in North America, we manufacture atomized and ground particulates in a wide range of shapes and sizes: chips, granules, coarse powders and fine powders. Our products are used for a variety of applications & markets including: military, steel desulphurization, chemical synthesis, welding, powder metallurgy, specialty pyrotechnics, and flameless rationheaters. METALPÓ IND. E COM. LTDA. www.metalpo.com.br Since its opening, in 1967, Metalpó has had its activities pointed to powder metallurgy as a nonferrous powders and sintered parts producer. Typical Metalpó powder metallurgy products are self-lubricating bearings (bronze and iron), structural parts (iron, stainless steel, bronze and brass) and metal powders (copper, bronze premix, prealloyed bronze and tin). Using modern methods and quality management systems Metalpó has had since its early years the acknowledgment for highest level of quality. This has earned the Metalpó quality management system the ISO 9001/2000 and ISO TS 16949 assessments. NORTH AMERICAN HÖGANÄS, INC. www.nah.com North American Höganäs, Inc., a subsidiary of Höganäs AB, is a supplier of iron-based metal powders and stainless steel powders designed for a broad spectrum of applications, including components, friction, welding, brazing, thermal coating, soft magnetic composites, electro photographic and numerous chem/met applications. Production takes place in four strategic locations: Stony Creek Plant, located in Hollsopple, PA, is the world's most integrated production resource for atomized iron and steel powders. St. Marys Plant, located in St. Marys, PA, is a mixing facility which is capable of producing small to truckload-size custom mixes. Niagara Falls Plant, located in Niagara Falls, NY, produces a comprehensive range of products ranging

from friction materials, powder metallurgy and soft magnetics, to food additives and general chemical use. Johnstown Plant, located in Johnstown, PA, produces a broad range of products including stainless steel powders, iron-alloy powders, nickel-alloy powders, electrolytic iron powders and chips, manganese and silicon powders, and GLIDCOP® dispersion-strengthened copper products. OM GROUP (OMG) www.omgi.com OM Group, Inc. (OMG) is a diversified global developer, producer and marketer of value-added specialty chemicals and advanced materials that are essential to complex chemical and industrial processes. With more than 30 years of experience in cobalt powders, OMG’s powders serves the needs of many industries including but not limited to hardmetals, diamond tools, PM, thermal spray and magnets. Other key technology-based end-use applications include affordable energy, portable power, clean air, clean water, and proprietary products and services for the microelectronics industry. Headquartered in Cleveland, Ohio, OM Group operates manufacturing facilities in the Americas, Europe, Asia and Africa. For more information, visit the company’s Web site at http://www.omgi.com. QMP AMERICA www.qmp-powders.com QMP, registered to ISO 9001, ISO 14001, and ISO/TS 16949, provides a full product line of iron and steel powders in the Americas, Europe, and Asia. ATOMET standard grades and prealloys, binder treated FLOMET™ mixes, diffusion-bonded ATOMET DB powders, machinable (sulphur-free) grades, sinter-hardening grades, and soft magnetic composite materials are available to customers worldwide. SCM METAL PRODUCTS, INC. www.scmmetals.com With manufacturing facilities in the U.S. and China, SCM Metal Products is a global, technological leader in the manufacturing and distribution of copper powders, pastes, flakes, alloys and oxides, as well as the North American sales and marketing arm for AMTIX ferrous and nonferrous MIM powders. SCM’s products serve

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 WEB SITE DIRECTORY

a wide array of applications including powder metallurgy, MIM, brazing, electronics, chemicals (silanes) and numerous industrial applications. Visit us at www.scmmetals.com.

www.advancedmetalworking.com for more information about the consistent quality of our feedstocks, discussion of dimensional precision, and background.

SUPERIOR GRAPHITE CO. www.superiorgraphite.com Superior Graphite specializes in thermal purification, advanced sizing, blending, and coating technologies, providing value-added graphite and carbon-based solutions globally. Combining 90 years of experience and advanced technologies into every facet of the organization, a wide range of markets are served such as: agriculture, battery/fuel cells, ceramic armor, carbon parts, ferrous/nonferrous metallurgy, friction management, hot metal forming, polymer/composites, powder metals, lubricity, and performance drilling additives.

BASF CORPORATION www.basf.com/catamold BASF Catamold® is a ready-to-mold feedstock for MIM and CIM. Our material portfolio includes various low-alloy steels, stainless steels, tool steel, soft magnetic alloys, super alloys, special alloys (Ti, W, others) and oxide ceramics. New grades will be developed as needed for our customers. Catamold® incorporates catalytic debinding and offers high green strength and dimensional stability. It is well suited for both batch and continuous PIM operations. www.basf.com/catamold.

UMICORE www.umicore.com Umicore Tool Materials is a business line of Umicore, serving the markets of diamond tools and hardmetal applications. We offer a wide range of cobalt powders, nickel powders and prealloyed alternatives (from our Cobalite range). Being a worldwide market leader, we see successful use of our products in tools for stone-cutting and construction, as well as hardmetal or cemented carbide applications. Our products provide the perfect solution to create bonds with other constituents like diamonds or tungsten carbide. Due to our extensive application know-how and R&D facilities, we can provide you with the necessary technical support.

MIM/PIM ADVANCED METALWORKING PRACTICES, LLC. www.advancedmetalworking.com Producer of high-quality feedstock for MIM since 1988—longer than any other supplier. ADVAMET® feedstocks are available for many steels and stainless steels and some nonferrous compositions. We can customize feedstocks for different target shrinkages. On-time shipments of feedstocks in tonnage quantities. Test lots for new customers or new applications. Visit our Web site Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

FLOMET LLC www.flomet.com FloMet is an ISO 9000:2000 registered custom manufacturer of precision, high-volume metal components with extremely difficult tolerance requirements, through the metal injection molding (MIM) process, producing custom components for various manufacturing markets, including Medical/Surgical/ Orthopedic, Dental/Orthodontic, Health/Hearing, Aerospace/Defense, Electrical, Telecommunications and Industrial. FloMet specializes in custom-blended feedstocks made of stainless steel, cobalt and nickelbased alloys, providing low-carbon and high-density components, which provide superior properties of strength and versatility. NETSHAPE TECHNOLOGIES, INC. www.netshapetech.com A manufacturer of engineered, complex, high-strength components using powder metallurgy and metal injection molding, focused on industrial markets. NetShape is a Lean-focused, global supplier with 5 PM and 1 MIM operations worldwide, including a facility in Suzhou, China. Industryleading technologies include high-performance materials, unmatched shape complexity, tolerances and part size. Our innovative Conversioneering® process and strong engineering support offer unmatched value and support for converting parts to PM.

REMINGTON ARMS COMPANY, INC., Powder Metal Products Division www.remingtonpmpd.com The Powder Metal Products Division has been a MIM parts producer since the mid-1980s and continues to supply Remington and a number of commercial customers with high-quality MIM parts, in medium-to-high volumes. We offer low-alloy steels, stainless steels, and soft magnetic materials for markets including ordnance and medical applications. Please visit our Web site at www.remingtonpmpd.com to learn more about MIM technology and our MIM product offering. RYER, INC. www.ryerinc.com Ryer, Inc., is a manufacturer, developer and supplier of custom and standard feedstocks for the metal injection molding industry. We offer the widest range of particle sizes, material types and de-binding methods in the MIM industry. As a custom compounder, Ryer can match your current material shrink specifications and flow characteristics. Ryer Feedstocks are inspected, tested and documented to assure you receive consistent, predictable results with "batch to batch" repeatability. SCM METAL PRODUCTS, INC. www.scmmetals.com With manufacturing facilities in the U.S. and China, SCM Metal Products is a global, technological leader in the manufacturing and distribution of copper powders, pastes, flakes, alloys and oxides, as well as the North American sales and marketing arm for AMTIX ferrous and nonferrous MIM powders. SCM’s products serve a wide array of applications including powder metallurgy, MIM, brazing, electronics, chemicals (silanes) and numerous industrial applications. Visit us at www.scmmetals.com.

OTHER GLOBAL PM CONSULTANTS www.globalpm.net Specializing in: PIM technology, metal powder production technology. Structural parts production technology incl. tooling, compaction and sintering. PM materials technology, properties and applications, PM semi-finished,

61

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 WEB SITE DIRECTORY

fully dense and hard materials. Services offered: Market research, technical forecasting and technology assessments; business developments; global licensing and technology transfer; international strategic partnership formation; reviews of international development trends; industrial applications of PM products and selection of PM materials; international recruitment consultancy.

and nuances of PM machining optimization. We don't offer a single solution for all PM alloys because it's simply not possible. Shape-Master utilizes over eight different PCBN grades for PM due to the differences between iron-carbon, Fe-Cu, Fe-Ni, low-alloy, as-sintered, copper-infiltrated, steam-treated, hardened, sinter-hardened, and powder-forged components.

JENIKE & JOHANSON, INC. www.jenike.com Jenike & Johanson, in business over 40 years, is an experienced consulting and engineering firm that specializes in powder flowability and engineering system for powders. We have a full service powder test lab to determine powder flow properties and behavior. We troubleshoot existing systems and design new processes to store, transport, feed, and reliably deliver powder consistently. We provide modeling, functional design, detailed design, and courses on powder flow to clients worldwide.

SINTER-PACIFIC (a Div. of International Sintered Components Pty Ltd) www.sinter-pacific.com Sinter-Pacific was established in October 1993 with a focus on providing our Asia Pacific customers with cost-effective design solutions using powder metal technology from the world’s best. Diversification has now provided PM products, specialty dry bearing technology, PM processing machinery & equipment along with NDT solutions for our customers.

KITTYHAWK PRODUCTS www.kittyhawkinc.com Kittyhawk Products—qualified experts in the field of hot isostatic processing. HIP is an affordable process of unique benefit in solving complex design problems while increasing the strength of properties. Together with our sister company, Synertech P/M Inc., we offer unmatched net-shape capabilities with powder metal parts design and manufacture. PSM INDUSTRIES, INC. www.psmindustries.com A symphony of PM solutions. Our 6 manufacturing divisions will find an answer to your most pressing PM problem. Specialties include highdense high-speed steels, high-shapecomplexity MIM and PM, steel-bonded carbides, tungsten carbides, highconductivity copper, and a wide variety of other specialties. Come visit our Web site at www.psmindustries.com. SHAPE-MASTER TOOL COMPANY www.shapemastertool.com Shape-Master Tool manufactures polycrystalline cubic boron nitride (PCBN) cutting tools for PM machining. With a metallurgical engineer on staff, Shape-Master understands PM

62

ULTRA INFILTRANT www.ultra-infiltrant.com Ultra Infiltrant is a wrought, homogeneous copper-based alloy that offers significant benefits over powder-form copper infiltrants. Benefits like less waste, improved productivity and increased strength. Ultra Infiltrant is available in custom configurations to accommodate virtually any automated process. Ultra Infiltrant was designed for copper infiltration of ferrous PM parts in today's cost-competitive manufacturing environments, where the handling of fragile green infiltrant slugs is difficult and can lead to excessive waste.

PM PRODUCTS OR PARTS PRODUCERS ACE IRON & METAL CO., INC. Ace Iron & Metal is a full-service metal recycling company in business since 1945. We purchase all types of powder metal scrap inclusive of green, sinter-floor sweeps, and all maintenance scrap, along with furnace scrap. We can be contacted via our e-mail address or our toll free number. [email protected] ALLREAD PRODUCTS LLC www.allreadproducts.com Allread Products is a very versatile

company which will manufacture large or small volumes of parts. Our pressing capabilities range from 4 ton presses up to 100 ton presses. We process multitudes of materials including ferrous and ferrous alloys, most nonferrous, stainless steel, aluminum, and Teflon. Our secondary department is quite extensive including 6 CNC machines and a number of small automatic machines for special applications. Along with these capabilities we also do assembly of various parts. ASCO SINTERING CO. www.ascosintering.com Manufacturer of precision complex multilevel structural powdered metal parts & assemblies. Experienced sintered metal engineering & metallurgical staff. Serving the automotive, lock, hardware, lawn & garden, irrigation, medical, hand tools, computer & cutlery industries. Capabilities include tool design, tooling, metallurgy, warm compaction, high-temperature sintering, sinter hardening, heat treat, resin impregnation, deburring, secondary machining, assembly & plating. Materials include low-alloy, diffused, copper, carbon & infiltrated steels, 300 & 400 stainless steels, brass, nickel silver, Monel®, soft magnetics, copper & bronze. ATLAS PRESSED METALS www.atlaspressed.com Atlas Pressed Metals has been a producer of powdered metal components since 1976. Atlas specializes in production of high-performance bearings, structural and gear components using iron, iron alloys, soft magnetic alloys, stainless steel, bronze, brass and custom materials. BODYCOTE HIP www.bodycote.com Bodycote is the world's leading provider of metallurgical services. Hot isostatic pressing (HIP) of PM components is just one of the many services that Bodycote provides, from CAM designs and fabrication to powder filling evacuation, sealing and HIP. FMS CORPORATION www.fmscorporation.com FMS Corporation is a precision manufacturer of high-performance sintered metal components, serving the off-road vehicle, aerospace, computer and home appliance industries, Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

2009 WEB SITE DIRECTORY

among others. Material capabilities include high-performance, high-density steels, stainless steel, soft magnetic materials, and many nonferrous alloys. Production capabilities include in-house tool design and manufacture, conventional and wire EDM, compaction from 2 to 1,100 tons, high-temperature vacuum sintering, CNC machining, grinding, lapping, resin and oil impregnation. METALPÓ IND. E COM. LTDA. www.metalpo.com.br Since its opening, in 1967, Metalpó has had its activities pointed to powder metallurgy as a nonferrous powders and sintered parts producer. Typical Metalpó powder metallurgy products are self-lubricating bearings (bronze and iron), structural parts (iron, stainless steel, bronze and brass) and metal powders (copper, bronze premix, prealloyed bronze and tin). Using modern methods and quality management systems Metalpó has had since its early years the acknowledgment for highest level of quality. This has earned the Metalpó quality management system the ISO 9001/2000 and ISO TS 16949 assessments. METAL POWDER PRODUCTS COMPANY www.metalpowderproducts.com Metal Powder Products Company is an international provider of customengineered powder metallurgy product solutions to customers in a variety of industries. MPP has developed a number of innovations in material formulation, sintering, densification, powder metallurgy joining techniques, and value-added secondary operations. MPP is the largest manufacturer of powder metal aluminum structural parts in North America. MI-TECH METALS, INC. www.mi-techmetals.com Mi-Tech Metals, Inc., located in Indianapolis, Indiana, produces tungsten heavy alloy and copper and silver tungsten composite materials. Additional materials include tungsten carbide and pure molybdenum and tungsten. Mi-Tech maintains inventory to meet immediate requirements and our extensive machine shop manufactures parts to print.

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

NETSHAPE TECHNOLOGIES, INC. www.netshapetech.com A manufacturer of engineered, complex, high-strength components using powder metallurgy and metal injection molding, focused on industrial markets. NetShape is a Lean-focused, global supplier with 5 PM and 1 MIM operations worldwide, including a facility in Suzhou, China. Industryleading technologies include high-performance materials, unmatched shape complexity, tolerances and part size. Our innovative Conversioneering® process and strong engineering support offer unmatched value and support for converting parts to PM. PLANSEE SE www.plansee-group.com With the four divisions PLANSEE High Performance Materials, GTP Global Tungsten & Powders, CERATIZIT Hard metals & tools and PMG PM-Products, the Plansee Group worldwide delivers excellence in powder metallurgy. The Group is active in 23 countries with 73 companies and has a headcount of 10,000 employees. The Group generates sales of 1.5 billion euros. Our powders and powder metal manufactured pre-finished components, semi-finished products and tools/production tools are used in the following industries: Electronics, lighting and medical technology, power engineering and mechanical engineering, automotive and construction industry. PSM INDUSTRIES, INC. www.psmindustries.com Six divisions offer highly engineered, technology-driven solutions which provide optimum performance at the lowest cost. Material experts – Technologies include PM, MIM, tungsten carbide, steel-bonded titanium carbide and fully dense tool steels. Small parts to large. Low and high volume. High-temperature sintering. Completed assemblies. Experienced new product development including prototypes and cost reducing existing components. Serving all markets including automotive. www.psmindustries.com.

SELEE CORPORATION www.selee.com SELEE Corporation, a member of the Porvair Group, manufactures hightemperature, low-mass kiln furniture in seven different ceramic compositions to meet your application’s specific needs. We make both open-cell foam kiln furniture as well as microporous kiln furniture. We are also a distributor for Ferro Process Temperature Control Rings. Our manufacturing facility is located in the beautiful Blue Ridge Mountains in Hendersonville, North Carolina, U.S.A. Certified ISO 9001:2000 and ISO 4001:2004. SMC POWDER METALLURGY www.smcpowdermetallurgy.com SMC Powder Metallurgy is a 57-year young PM manufacturer, diverse in the materials supplied, the business markets served, and the parts manufactured. SMC Powder Metallurgy manufactures in a modern 112,000 sq. ft. facility located in Galeton, Pennsylvania, dedicated solely to the manufacturing of powder metal components. SMC Powder Metallurgy is TS-16949 certified company. For additional detail, please visit our Web site at www.smcpowdermetallurgy.com. STERLING SINTERED TECHNOLOGIES www.sterlingsintered.com Sterling Sintered Technologies, an ISO 9001-2000 company, is an innovative leader in the manufacture of powdered metal components. The Sterling team works with customers to concurrently design parts and processes for them. This approach has allowed Sterling Sintered and its customers to develop new applications and push PM technology to the forefront of our industry. Let Sterling Sintered do this for you. For additional information explore our Web site at www.sterlingsintered.com WESTERN SINTERING CO. INC. www.westernsintering.com Manufacturer of custom powder metal parts. Presses to 300 tons. Steel, stainless steel, and copperbase materials. Complete secondary facilities and heat treat in-house. ijpm

63

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

ADVERTISERS’ INDEX

ADVERTISER

FAX

WEB SITE

PAGE

ACE IRON & METAL CO. INC.___________________(269) 342-0185 _________________________________________________________5 ACUPOWDER INTERNATIONAL, LLC _____________(908) 851-4597 ___________www.acupowder.com ___________________________37 CM FURNACES, INC. _________________________(973) 338-1625 ___________www.cmfurnaces.com ___________________________7 HOEGANAES CORPORATION ___________________(856) 786-2574 ___________www.hoeganaes.com ___________INSIDE FRONT COVER NORTH AMERICAN HÖGANÄS INC. ______________(814) 479-2636 ___________www.nah.com __________________INSIDE BACK COVER SCM METAL PRODUCTS, INC. __________________(919) 544-7996 ___________www.scmmetals.com ____________________________3 QMP ______________________________________(734) 953-0082 ___________www.qmp-powders.com ________________BACK COVER

ADVERTISER’S REQUEST FOR INFORMATION FAX FORM Need more information on products or services seen in this issue? Complete the form below and fax to the advertiser(s) of your choice. Fax numbers are listed in the advertisers’ index above.

international journal of

powder metallurgy

To:___________________________________ Fax #: ____________________________________________________________________ Company: _______________________________________________________________________________________________________ Please send me more information on: __________________________________________________________________________ __________________________________________________________________________________________________________________ as advertised in the __________ issue of the International Journal of Powder Metallurgy. Please send information to: Name: Title:______________________________________________________________________________________________________ Company: _______________________________________________________________________________________________________ Address: _________________________________________________________________________________________________________ City:____________________________ State:_______________ Postal Code: ____________________________________________ Country: _________________________________________________________________________________________________________ Phone:___________________ Fax:___________________ E-Mail: ______________________________________________________

64

Volume 45, Issue 1, 2009 International Journal of Powder Metallurgy

Previous

1-Page View

2-Page View

Search

Table of Contents

Next

Previous

1-Page View

2-Page View

Search

Table of Contents