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EDITORIAL REVIEW COMMITTEE P.W. Taubenblat, 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 J.W. Newkirk P.D. Nurthen J.H. Perepezko P.K. Samal H.I. Sanderow 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 (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) S. Saritas (Turkey) G.B. Schaffer (Australia) 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
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powder metallurgy Contents 2 5 9 11 15 16
44/4 July/August 2008
Editor's Note PM Industry News in Review PMT Spotlight On …Luis Bernardo Zambrano Merino Consultants’ Corner Harb S. Nayar, FAPMI 2008 APMI Fellow Awards Paul Beiss and Pierre Taubenblat 2008 Poster Awards H. Jorge and A.M. Cunha J. Martz, C. Braun and S.C. Johnson
20 Kempton H. Roll Powder Metallurgy Lifetime Achievement Award Arlan J. Clayton 21 2008 PM Design Excellence Awards Competition Winners P.K. Johnson
RESEARCH & DEVELOPMENT 27 Consolidation of Aluminum Powder During Extrusion V.V. Dabhade, P. Kansuwan and W.Z. Misiolek
GLOBAL REVIEW 37 Powder Metallurgy in India G.S. Upadhyaya
HISTORICAL PROFILE 43 Tungsten Filaments—The First Modern PM Product P.K. Johnson
ENGINEERING & TECHNOLOGY 49 State of the PM Industry in North America—2008 M. Paullin
DEPARTMENTS 53 Book Review 55 Meetings and Conferences 56 Advertisers’ Index Cover: Grand Prize–winning parts from MPIF’s 2008 Design Excellence Awards Competition. 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 © 2008 by APMI International. Subscription rates to non-members; USA, Canada and Mexico: $95.00 individuals, $220.00 institutions; overseas: additional $40.00 postage; single issues $50.00. 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:
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EDITOR’S NOTE
T
he 2008 World Congress on Powder Metallurgy & Particulate Materials is now history. By any yardstick this international event was a success. This post-show issue of the Journal includes the text of the “State of the PM Industry in North America—2008” address given by MPIF President Mark Paullin, and Peter Johnson’s review of the “2008 PM Design Excellence Awards” competition. Parts receiving a Grand Prize are displayed on the front cover. 2008 marks the centenary of the incandescent ductile-tungsten lamp filament. In a fascinating historical chronology, Peter Johnson traces the R&D leading to this invention by William Coolidge. Little has changed in the commercial process for fabricating ductile-tungsten filaments since they were introduced in 1908! India is experiencing a boom in its manufacturing base, including PM processing. In his “Global Review,” Gopal Upadhyaya has compiled a comprehensive update on metal powder and parts production, including cemented carbides, and advanced ceramics. Also included is a current assessment of R&D in academe, the PM industry, and government facilities. Reducing costs and increasing productivity to offset rising energy and raw material costs has become a necessary goal of PM parts producers in North America. To this end, Harb Nayar offers a simple but documented approach in the “Consultants’ Corner.” Reader reaction is encouraged. In the “Research & Development” section, Dabhade et al. examine the consolidation behavior of aluminum powder during extrusion, based on two-dimensional and three-dimensional density/porosity contour maps and attendant hardness levels. The study identifies the importance of particle shape on extrusion response. I offer congratulations to Paul Beiss and Pierre Taubenblat, the 2008 APMI Fellow Award recipients. Both are long-time professional peers and have made seminal contributions to APMI and the PM industry. Also, congratulations to Arlan Clayton, the first recipient of the Kempton H. Roll Powder Metallurgy Lifetime Achievement Award. Arlan served as a director of APMI from 1995 to 1999.
Alan Lawley Editor-in-Chief
Diran Apelian, a Fellow of APMI International, is currently serving as the 52nd president of the Minerals, Metals and Materials Society (TMS). He has initiated a monthly “Presidential Perspective” (PP) and, with a foot in both camps (APMI and TMS), I found the focus of a recent PP of particular interest vis-à-vis APMI. The expanding field of minerals, metals, and materials is seen by Diran as a major challenge to TMS. He notes that, compared with two or three decades ago, the “new professional” schooled in materials science and engineering (MSE) can now be found working in diverse fields such as food processing, biomaterials, fuel cells, nanotechnology, microelectromechanical systems, computational sciences, advanced polymers, drug delivery, and pharmaceutical science. How can TMS be the voice of this new professional in the broadened domain of MSE? One can readily substitute APMI for TMS in this context. How will our scientific/technological society (APMI) embrace and engage the new MSE professional?
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Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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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.”
Big Tungsten Deal Signed The Plansee Group, Reutte, Austria, has agreed to purchase the Global Tungsten & Powders (GTP) business unit from OSRAM GmbH, Munich, Germany, a Siemens company, for an undisclosed amount. GTP, which posted fiscal year 2007 sales of approximately 280 million euros (about $437 million), employs 1,050 people in plants in Towanda, Pa., and Bruntál, Czech Republic. Atomization Course in U.K. Atomising Systems Limited, Sheffield, U.K., will conduct a course entitled Atomisation for Metal Powders, October 20–21, 2008, at the University of Salford in Manchester, U.K. The course will cover the fundamental principles of atomization and the primary methods of spraying metals. Chinese Auto Industry Booming Last year 5.2 million passenger vehicles were sold in China, reports Automotive News in its 2008 Guide to China’s Auto Market. Overall sales jumped 21 percent compared to 2006, while sales of SUVs surged 50 percent to 357,000 units. Web Site Re-Launched The NanoSteel Company has relaunched its Web site nanosteelco. com. The new site includes a new design, easier navigation, and new content enhancements. Furnace Company’s Silver Anniversary Abbott Furnace Company, St. Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
Marys, Pa., celebrates 25 years in business with a series of special events. Incorporated in 1983, the privately held company makes mesh-belt and pusher sintering furnaces, as well as annealing, brazing, and glass-to-metal-sealing furnaces. Sales Growth at European PM Parts Maker Sales for the 2007–08 fiscal year at Miba AG, Laakirchen, Austria, rose 17.5 percent to 387.7 million euros (about $600 million). Earnings before interest and taxes increased 24.5 percent to 27.6 million euros (about $43 million). Mammoth HIP Press Installed The Northwest regional service center of Bodycote–HIP in Camas, Wash., has taken delivery of an Avure Technologies Inc. high-capacity hot isostatic press (HIP). It is identical in size to a unit installed in 1998, with the two units ranking as the largest HIP presses ever built, Avure reports. New Line of Porous Metal Spargers Mott Corporation, Farmington, Conn., offers a new line of quickchange spargers that reduce the time to replace sparger elements in bioreactors and fermentors. The porous metal element can be purchased with an adapter that allows easy assembly to the mating sparger tip and easy removal for replacement.
American Axle Strike Settlement Brings Good News for the PM Industry American Axle & Manufacturing Holdings, Inc. (AAM), Detroit, Mich., has settled the 12-week strike with the International UAW representing about 3,650 workers at five plants in Michigan and New York. AAM says it expects to have its plants onstream again during the week of May 26. New Bodycote Acquisitions Bodycote International plc in the UK has acquired three UK companies: Plasma & Thermal Coatings Ltd., Greenhey Engineering Services, and NPE Innotek Ltd. The acquired companies join the Metallurgical Coatings division of Bodycote’s Thermal Processing Group. PM2008 World Congress Draws Large International Audience Beginning with the welcoming reception and dinner on June 8, the 2008 World Congress on Powder Metallurgy & Particulate Materials was attended by more than 1,600 delegates. Powder metallurgists and industry executives from 40 countries learned about hot new PM developments and the latest company news through networking and attending technical sessions and the trade exhibition. The International Business Picture The presidents of MPIF, the European Powder Metallurgy Association (EPMA), and the ijpm Japan
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Powder Metallurgy Association (JPMA) reviewed PM industry conditions in their respective regions at the Tuesday morning Global General Session of PM2008. Statistics they presented revealed that metal powder shipments declined in 2007 in North America while rising in Europe and Asia. SCM Enters South American Market SCM Metal Products, Inc., Research Triangle Park, N.C., has signed a joint development agreement with Metalpó Industria e Comercio Ltda., São Paulo, Brazil. The two companies will collaborate on process and product developments for Metalpó’s plant in Brazil.
PM Automotive Applications Growing New engines and six-speed transmissions contain more PM parts, reported Mark Paullin, MPIF president, in his address on the state of the North American PM industry at the recent PM2008 World Congress. The new GM HighFeature 3.6L V-6 DOHC engine contains about 36 pounds of PM parts and new six-speed transmissions contain from 18 to 26 pounds of PM parts. Miba Sales and Earnings Grow Miba AG, Laarkirchen, Austria, reports first-quarter fiscal year sales grew 20.2 percent to 102.2 million euros (about $160 million). Earnings before interest and taxes jumped by 47 percent to 13.3 million euros (about $21 million).
New Large Isostatic Press Avure Technologies, Kent, Washington, is building a very large hot isostatic press at the Bodycote plant in Surahammar, Sweden. The completion target is sometime during late 2009. New PM Main Bearing Cap Metaldyne, Plymouth, Mich., an ASAHI TEC company, is making a new powder metallurgy crankshaft main bearing cap for mediumduty diesel engines. Its customer is MWM International Motores in Brazil, a subsidiary of Navistar. Plansee Sales Rise Fiscal year 2007/2008 sales of Plansee Group, Reutte, Austria, rose 11 percent, exceeding $1 billion euros (about $1.56 billion). All three divisions—HPM, Ceratizit, and PMG—contributed to the growth, the company reports.
PURCHASER & PROCESSOR
Powder Metal Scrap (800) 313-9672 Since 1946
Ferrous & Non-Ferrous Metals Green, Sintered, Floor Sweeps, Furnace & Maintenance Scrap ijpm
1403 Fourth St. • Kalamazoo, MI 49048 • Tel: 269-342-0183 • Fax: 269-342-0185 Robert Lando E-mail:
[email protected] 6
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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International: powder injection molding. If you wish to produce complex ceramic and metal products using the PIM process, then come to the leading international specialists in this field: ARBURG. For you, we have the appropriate ALLROUNDER machine technology and the required know-how from our PIM laboratory. With our expertise, you will be able to manufacture efficiently and to the highest quality, prepare material, injection-mold components, debind and sinter - finished! You want to find out more about PIM processing? Simply talk to us!
ARBURG GmbH + Co KG Postfach 11 09 · 72286 Lossburg/Germany Tel.: +49 (0) 74 46 33-0 Fax: +49 (0) 74 46 33 33 65 e-mail:
[email protected] ARBURG, Inc. · 125 Rockwell Road · Newington, CT 06111 · Tel.: +1 (860) 667 6500 · Fax: +1 (860) 667 6522 · e-mail:
[email protected] www.arburg.com
PM 8 at Euro r 1, 200 Visit us r 29 - Octobe e b m y te n p a e S rm eim, Ge Mannh
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SPOTLIGHT ON ...
LUIS BERNARDO ZAMBRANO MERINO, PMT Education: Mechanical Engineer, Universidad del Bio-Bio (Concepción, Chile), 1970 Industrial Administrator, Universidade de São Paulo, USP (São Paulo, Brazil), 1987 Why did you study powder metallurgy/particulate materials? When I graduated in Chile in 1970, I wanted to work in different fields of metallurgical processing. From 1970 to 1974 I was working with processes such as machining, tube and weld profiles, production of iron sheet, and engineering design. Then I moved to São Paulo, Brazil, and began working in the area of PM processing. When did your interest in engineering/science begin? Before finishing second grade in a Catholic industrial school in 1967, I decided to go to a university and study to be a mechanical engineer. My objective was to gain knowledge, and thereby improve my professional life. What was your first job in PM? What did you do? My first job in PM was with Brassinter, from 1974 until 1977, in São Paulo. At that time this company was the primary PM parts manufacturer in Brazil; it reflected high-quality technology, equipment, and technical staff. I was involved in designing tools, devices, and equipment for the production of PM parts, ranging from self-lubricating bearings to gears and gerotors for oil pumps, multi-level structural parts, and shock absorbing parts for automotive and home appliances. Describe your career path, companies worked for, and responsibilities. At Brassinter, I started my career as a tool designer. In my second year I was promoted to design-area supervisor and the following year I became head of the design area. I am familiar with all types of equipment
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
involved in the PM process, such as compaction and sizing presses, continuous and walking-beam furnaces, machines for secondary operations, and machining. I had to understand all types of machines in order to design tooling for the production of PM parts. My second PM job was with Metalpó, in São Paulo, from 1977 until 2001. I was responsible for developing their design department, putting into practice the knowledge gained from my industrial experience. In addition to the design department, I was also manager of the tool room and engineering sector. After an interrupted period from 1992 to 1995, I worked as a factory 1 coordinator, manufacturing complex structural parts. From 2001 until the present time, I’ve worked as technical director, Termosinter, a new company in Brazil. The company develops PM parts, and designs and builds its own equipment, presses, and furnaces. What gives you the most satisfaction in your career? I enjoy working on special PM processes because they always relate to improving new PM parts, researching better process materials and applications. I also enjoy sharing my knowledge with coworkers and helping customers and suppliers to identify the best possible product for their needs. The greatest satisfaction in my career has been the opportunity to, and capability of, improving the technology in the companies I have worked for, after my Technical Director Termosinter Ind. e Com. Ltda. Milton José Nunes Fernandes, 600 Chacara Santa Maria Guaratinguetá São Paulo CEP 12500-971 Brazil Phone: 012 3122 1146 Fax: 012 3122 1146 E-mail:
[email protected] 9
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SPOTLIGHT ON ...LUIS BERNARDO ZAMBRANO MERINO, PMT
first experience with Brassinter. This company provided an excellent background in PM, and from that time on I have striven to continue to improve my knowledge in order to stay up-to-date with PM developments. I have worked in most areas of PM processing, from tool design, product engineering, and production to maintenance and technical support. List your MPIF/APMI activities. I have been a member of APMI since 2000, when I obtained Level I PMT certification. I have attended many conferences and seminars, and visited PM companies in Brazil, Spain, and the U.S., for the purpose of technology transfer. What major changes/trend(s) in the PM industry have you seen? Since 1974, I have seen interesting and positive trends in all activities involved in PM technology, primarily in relation to raw materials and process evolution in order to increase density and the mechanical properties of PM parts. This has resulted in tool materials with improved properties to enable higher densities, new compaction presses capable of more rapid production of parts
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with enhanced density distributions, process stability, and sintering furnaces capable of handling sinter-hardening steels. In the engineering field, CAD, CAE and CAM have replaced tedious manual design and calculation. Why did you choose to pursue PMT certification? The pursuit of PMT certification in 2000 was, to me, confirmation of the background I obtained during my years involved with the PM process. How have you benefited from PMT certification in your career? Personally, I am now recognized at seminars, conferences, and customer technical meetings. I feel confident as a PM specialist and, therefore, the pursuit of PMT certification was a sound benchmark in my career. What are your current interests, hobbies, and activities outside of work? Because I live in a small city, GuaratinguetáSão Paulo, I can spend time with my family, and visit nearby cities. Every Sunday morning I play soccer with my grandson Luis Gustavo, who is 18 years old, at a sports club in our neighborhood. ijpm
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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CONSULTANTS’ CORNER
HARB S. NAYAR, FAPMI* Q
How can powder metallurgy (PM) parts makers reduce costs and increase productivity to offset rising energy and raw materials costs? This is an important question for any industry, but critical for the well-established conventional PM parts industry. I will answer the question in the form of a very simple thought process or step-by-step methodology that can be applied to any existing PM parts manufacturing plant. The process applies only to the production unit or building of any PM parts company. For purposes of explanation, we will assume that the existing plant is small with bare minimums: building or manufacturing space, a single press and a single sintering furnace, and quality control (QC) equipment as capital items. The operation produces a variety of single-press/single-sinter iron-base PM parts requiring no secondary operations and the plant uses pre-blended powders. Another assumption is that the company’s sales department has no problem getting orders to keep the plant operating 24/7. The simple thought process includes the following key phrases and words: • Walkthru • Snapshot • Utilization factor • Standardized yardsticks such as cost per unit weight (not cost per piece) • Bottlenecks The key to this thought process is “Let us take a walkthru” the plant or a single piece of equipment such as a press or furnace, or a process such as compacting or sintering. While the “walkthru” concept is simple and easy to follow, its full and diligent practice can be potentially effective in increasing productivity (weight of PM parts shipped per month or per year) in a given manufacturing plant and decreasing total manufacturing cost per unit weight of shipped PM parts. There are a minimum of two levels of walk, namely fast and slow. If need be, a third level walk (very
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slow) can be carried out to fine tune productivity in a given plant. Each level will have a starting point with an imaginary guard and an end point with another imaginary guard. In order to realize the benefits of the “walkthru” thought process, it is essential to take a 12-month “snapshot” (Step 1) of the PM manufacturing plant. One year is either the previous calendar year or the year just prior to the application of the “walkthru” process. This year-long “snapshot” provides reference points or benchmarks for comparison with future performance of the plant. STEP 1: One-Year “Snapshot” of the Plant Obtain the following information related to manufacturing from the purchasing and financial departments for the past 12-month period: • Total powder (by weight) received into the plant and dollars • Total labor (operators, supervisors, and managers) related to the plant in terms of employeehours and dollars • Total energy (electricity and gas) used by the plant in units and dollars • Total atmosphere (each type) used in volume and dollars • Purchase of major replacement items such as dies, belts, muffles, and heating elements in actual number and dollars for each item • Purchase of all other replacement items brought into the plant in terms of total combined dollars • Depreciation of major capital units such as the building, presses, furnaces, and QC equipment in terms of dollars for each type Ask the shipping department to provide the total amount of sintered product (by weight) shipped to customers during the same 12-month period. Using the preceding information received from the
*President, TAT Technologies, Inc., P.O. Box 1279, Summit, New Jersey 07902-1279; Phone: 908-391-9478; E-mail:
[email protected] Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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CONSULTANTS’ CORNER
various departments, the following benchmarks can be calculated: Benchmark 1. Manufacturing cost per unit weight of shipped parts: Total weight shipped during the year divided by total of all the cited costs combined. Benchmark 2. Material utilization factor: Total PM parts shipped by weight divided by the total weight of powder received. Benchmark 3. Energy used per unit weight of shipped PM parts both in terms of Kw and dollars. Benchmark 4. Atmosphere used per unit weight of shipped parts in terms of volume and dollars. Benchmark 5. All labor related to manufacturing per unit weight of PM parts shipped both in terms of employee-hours and dollars. Benchmark 6. Purchased parts in each of the major replacement items in terms of dollars per unit weight of PM parts shipped. Benchmark 7. Depreciation cost per unit weight of shipped PM parts for each of the major capital units such as presses, furnaces, and the building. These seven calculated pieces of information are the benchmarks or reference points. By applying the “walkthru” thought process (steps 2 to 5) in a systematic, speedy and diligent manner, these calculated costs and units can be significantly improved—in my opinion by up to about 30% for each of the seven. STEP 2: Fast Walk The fast walk with the product is from point A (on one side of the plant where powder is received) to point B (on the other side of the plant), where finished PM parts are ready for shipment to customers. In walking from point A to point B, we break down the distance between points A and B into segments or departments. In our example of the plant, we break it down into three departments. Department #1 is compacting, Department #2 is sintering, and Department # 3 is packaging/shipping. We now assign an imaginary guard at the start of each of the three departments. The duties of the guard at the start of each department are: • Material Utilization (MU) Factor: Check the quality of the material (powder, green parts, or sintered parts) entering the guard’s department. Material that meets specifications is allowed to enter the department but the balance is rejected. The guard records the amount by weight that is allowed to enter the guard’s assigned department, compared with what was consid-
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ered for entry. The ratio of the two numbers is called the Material Utilization (MU) factor for that department. For the compacting department it is MUc. A value of 1 is ideal; a value 14J (10·3 ft.·lb.). Replacing forged and machined parts, PM offered substantial cost savings with a net-shape design that eliminated the need for machining. Capstan Atlantic, Wrentham, Massachusetts, captured the Grand Prize in the Hardware/
Appliances category for a PM steel gear set (Figure 5) used in a high-volume business machine printer. The gear is roll densified to a surface density of 7.8 g/cm3. It has an American Gear Manufacturers Association (AGMA) quality of precision level 10 and the pinion, an AGMA precision level of eight. The core density of the gear and pinion is 7.3 g/cm3. The gear-tooth-surface fatigue resist-
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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2008 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
Figure 6. Stainless steel articulation gear
AWARDS OF DISTINCTION Four parts were selected for Awards of Distinction, Figure 7. Cloyes Gear & Products Inc., Paris, Arkansas, received the Award of Distinction in the Automotive—Engine category for PM low-alloy steel intake and exhaust sprockets (Figure 8) used in a variable valve timing (VVT) system in a high-performance, double-overhead cam V-6 engine. Using warm compaction, the sprockets are formed to a density of 7.25 g/cm3. The powder and tooling temperature is controlled to within 2.8°C (5°F). The 7.7 mm (0.3 in.) fine-pitch inverted sprocket teeth are compacted to a nearnet shape. The complex design provides a multifunction part, namely, a high-strength timing sprocket that performs cam-phasing functions. The teeth are induction heat treated and tempered to a 70 HRA typical apparent hardness. The overall length, slot width, and minor diameter are ground to tolerances of .012 mm (0.00047 in.). Each sprocket has a typical tensile strength of 1,169 MPa (170,000 psi), a 358 MPa (52,000 psi) fatigue limit, and a compressive strength of 1,262 MPa (183,000 psi).
ance equals that of a wrought steel 8620 carburized gear. The apparent hardness is >40 HRC and the microindentation hardness is 60 HRC. The part, which has opposing helix angles, is formed to net shape, except for hard turning the datum journals. Single pressed, the PM gear replaced two machined gears at a cost savings of >40 percent. Parmatech Corporation, Petaluma, California, won the Grand Prize in the Medical/Dental category for a 17-4 PH stainless steel articulation gear (Figure 6) used in a surgical stapling device. It functions as the drive and locking mechanism to articulate the head of the device at different angles. Made by MIM to a density >7.65 g/cm3, the part has an ultimate tensile strength of 900 MPa (130,500 psi), a yield strength of 730 MPa (106,000 psi), and a 25 HRC hardness. The complex MIM design is formed to net shape and requires no finishing operations. It has tight tolerances and provided a 70 percent cost savings, compared with machining the gear from bar stock.
Figure 7. Award of Distinction winners
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Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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2008 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
Figure 9. Stainless steel bobbins
Figure 8. VVT low-alloy steel intake and exhaust sprockets
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
ASCO Sintering Company, Commerce, Califor nia, and its customer Per for mance Friction Corporation, Clover, South Carolina, won the Award of Distinction in the Automotive— Chassis category for a series of 316 stainless steel bobbins (Figure 9) used in a new braking system for race cars and high-performance vehicles. The
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2008 PM DESIGN EXCELLENCE AWARDS COMPETITION WINNERS
two-level part is available in 14 variations with eight or more bobbins used in a single brake rotor assembly. The new bobbin design aids in tripling the brake-rotor fatigue life, reducing drag at elevated temperatures, as well as reducing vibration and temperature. PM was chosen over a wrought machined design. The parts are made to a density of 7.0 g/cm3 and have a tensile strength of 480 MPa (70,000 psi), a yield strength of 310 MPa (45,000 psi), 130 MPa (19,000 psi) fatigue
Figure 10. 17-4 PH stainless steel lock-cylinder parts
Figure 11. Hearing aid receiver cans
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strength, 13 percent elongation, 65 J (48 ft.·lb.) impact strength, and HRB 65 hardness. Kinetics Climax, Inc., Wilsonville, Oregon, won the Award of Distinction in the Hardware/ Appliances category for three 17-4 PH stainless steel lock-cylinder parts (Figure 10) made by MIM for Black & Decker Hardware and Home Improvement, Lake Forest, California. The MIM parts (a locking bar, pin, and rack) operate in the Kwikset SmartKey lock cylinder, which contains one locking bar, five pins, and five racks, totaling 11 MIM parts. The high-precision parts have a typical density of 7.7 g/cm3, a tensile strength of 900 MPa (130,500 psi), and a yield strength of 730 MPa (106,000 psi). The complex PM design provides significant cost savings and allows the consumer to re-key the lock easily, without removing it or getting professional help. FloMet LLC, Deland, Florida, and its customer, Starkey Laboratories, Inc., Eden Prairie, Minnesota, won the Award of Distinction in the Electrical/Electronic Components category for a hearing aid receiver can (Figure 11) made by MIM. The thin-walled part is made from a nickel–iron–molybdenum alloy that provides the magnetic shunt effect required in the hearing aid to separate the internal receiver signal from the telecoil signal. The part was previously deep drawn and required several interim annealing steps to achieve the necessary depth, in addition to forming the internal undercuts. Choosing the MIM manufacturing process provided a 50 percent cost savings over deep drawing as well as improved performance. FloMet performs a special sizing/coining operation to maintain tolerances on the OD and ID. The awards were presented during the PM2008 World Congress held in Washington, D.C., June 8–12, sponsored by MPIF and APMI. Past winners of the MPIF PM Design Excellence Awards Competition can be viewed by visiting www.mpif.org.
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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RESEARCH & DEVELOPMENT
CONSOLIDATION OF ALUMINUM POWDER DURING EXTRUSION Vikram V. Dabhade*, Panya Kansuwan** and Wojciech Z. Misiolek***
INTRODUCTION Due to their attractive physical and mechanical properties, aluminum powder metallurgy (PM) components have found numerous applications in automotive, aerospace, power tools, and appliances, and as structural elements. Aluminum PM components exhibit low density, good corrosion resistance, high thermal and electrical conductivity, and excellent machinability, and respond well to several finishing processes. In addition they offer the ability to produce complex netor near-net-shape parts, thereby eliminating or reducing the operational and capital costs associated with intricate machining operations. 1,2 The mechanical properties of aluminum alloys can be significantly improved by forming aluminum matrix composites, including a new generation of nanocomposites.3,4 PM compacts are subjected to secondary processing techniques such as extrusion, rolling, and forging to provide the desired shape to the product, reduce the level of porosity (enhance density), and modify the microstructure to improve mechanical properties. These secondary operations are usually perfromed after sintering as the component achieves sufficient strength to withstand the forming operations.5,6 Although sintering has the beneficial role of imparting strength and improving density, it leads to grain growth (with an attendant reduction in mechanical properties), and the formation of oxides or other undesired products via reaction with the sintering atmosphere (especially for highly reactive materials). Sintering also adds to the manufacturing cost. Of the secondary forming operations applied to PM components, extrusion is particularly attractive as the three principle stresses in the deformation zone are compressive6 and the extrusion parameters can be adjusted to obtain the desired structure.7 Powder extrusion can be used to make useful shapes such as seamless tubes, wires, and complex solid and hollow sections from materials that would be difficult (or even impossible) to process by casting or other metalworking operations. The extrusion process also offers the ability to form wrought structures from powders without the need for sintering. Additionally, reduced extrusion pressures and a wider range of temperature and
The present investigation focuses on the consolidation of aluminum powder by extrusion. Three grades of aluminum powder with average particle sizes of 365 µm, 135 µm, and 89 µm were precompacted to ~73% of their pore-free density. The precompacted billets were extruded at an extrusion ratio of 2.1 for different ram displacements in the range of 12%–99% of the initial billet length. The consolidation behavior of each grade of powder was determined from two-dimensional (2D) and three-dimensional (3D) density/porosity contour maps and from hardness levels following extrusion.
*Post Doctoral Research Associate, ***Loewy Professor of Materials Forming and Processing, Institute for Metal Forming, Lehigh University, 5 E. Packer Avenue, Bethlehem, Pennsylvania 18015, USA; E-mail:
[email protected], **Lecturer, Department of Mechanical Engineering, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
Volume 44, Issue 4, 2008 International Journal of Powder Metallurgy
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CONSOLIDATION OF ALUMINUM POWDER DURING EXTRUSION
ram velocity are possible in powder extrusion, compared with those in the extrusion of cast billets. Powder extrusion has been used in the processing of composite materials, superalloys, dispersion-strengthened materials, ferrous alloys, and light metals.8 Ductile metal powders such as aluminum and copper can be cold consolidated to their pore-free density by extrusion without the need for sintering if plastic deformation follows the consolidation stage. 9 This leads to the retention of the microstructure of the powder particles, and achieves the desired density and mechanical properties. This is particularly useful in the case of aluminum alloys in which sintering is difficult due to the presence of an oxide layer on the powder particle surfaces and the necessity to control dew point during sintering.10 The extrusion of aluminum powders also leads to shear deformation which, in combination with pressure, ruptures the oxide film on the particle surfaces and facilitates metallurgical contact between the particles and enhanced mechanical interlocking of the particles.8 Powder extrusion has been used to consolidate/improve the mechanical properties of aluminum powders,7 aluminum alloy powders,11 and aluminum particulate composites. 12,13 In the present investigation the effects of aluminum particle size, shape, and ram displacement on densification of the precompacted billet and extrudate has been investigated. The objective was to better understand the densification behavior of aluminum powders in extrusion as a precursor to nanocomposite processing. EXPERIMENTAL Powder Characterization Air-atomized aluminum powders of three different grades (AM 603, AM 605, and AM 625) obtained from AMPAL Inc. were used in the present investigation. The chemical analyses of the three powder grades, as obtained from the supplier, are shown in Table I. These analyses were
determined using inductively coupled plasma– atomic emission spectroscopy (ICP-AES). The average particle sizes of the three grades of powder were determined using a laser particle-size analyzer. The flow rates of the three powder grades were measured using a standard Hall flow apparatus. Optical micrographs of the mounted powders (Figure 1) were used to determine the grain size and shape distribution of the powders. The epoxymounted powders were polished and etched with 50 v/o concentrated H 2 SO 4 for 3 min and observed under a light optical microscope. Precompaction of Powder Billets Precompacted powder billets were fabricated by uniaxial compaction of the aluminum powders into cylindrical billets in an extrusion container. Approximately 16 g of each grade of powder were compacted into cylindrical billets 40 mm height × 15.97 mm dia., to a green density of approximately 73% of the pore-free density of aluminum. Zinc
(a)
(b)
TABLE I. CHEMICAL COMPOSITION OF POWDERS (w/o) Powder Grade AM 603 AM 605 AM 625
Other Metallics Al
Si
99.7 min* 0.13 0.08 Cr