Members of the Metal Powder Industries Federation (MPIF), Princeton, N.J., once again prove inventive powder-metal (P/M) parts can outperform their machined, stamped, cast, and forged counterparts.
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Grand prize winners
The Ferrous grand prize went to BorgWarner Powdered Metals Inc., Livonia, Mich., and its customer BorgWarner Transmission Systems, Auburn Hills, Mich., for input and third-position outer races used in GM's 4T65-E transmissions. The parts are selectively densified on the surface of the pocket to thwart wear. The races are heat treated to minimize part distortion and meet stringent strength and fatigue-life specs. Inside diameters of both parts have six pocket forms that hold locking pawl and spring elements. The parts sport an ultimate heat-treated tensile strength of 131 kpsi, an impact energy of 12 ft-lb, and a minimum 32 HRC hardness. P/M dropped part cost 20% compared to forged outer races.
A complex, 316 stainless-steel support cover used in a high-security military application captured the Stainless Steel grand prize. Webster-Hoff Corp., Glendale Heights, Ill., forms the cover as a net shape (except for deburring) with flatness and slot width tolerances of 0.005 in.
During compaction, technicians measure two level dimensions and part weight hourly for statistical process control. The levels maintain a CPK of 1.33 and weight is held to within 3% with a CPK of less than one. The cover has a density of 6.5 gm/cm 3 , a 59 HRB hardness, and ultimate tensile and yield strengths of 41 and 34 kpsi, respectively.
Advanced Materials Technologies Pte. Ltd., Singapore, garnered the Injection Molded grand prize for a highly complex copper connector used in an electrical appliance plug and adapter. Singapore-based Eubiq Pte. Ltd. designed the metal injection-molded connector to let existing three-pin plugs engage anywhere along a power track. The connector has a density of 8.8 gm/cm 3 , an elongation of 45%, and respective ultimate tensile and yield strengths 36 and 8.7 kpsi. MIM let Eubiq shave 20% off part cost compared to stamped, turned, machined, and press fit alternatives.
A camshaft sprocket used in a 4.0-liter V6 engine raced away with the Overseas grand prize. Sinterstahl Füssen GmbH, Füssen, Germany, devised innovative tooling with three lower and two upper punches to form the net shape sprocket from an iron carbon-molybdenum-chromium alloy. This is the first known application of a chromium-based sinter-hardened material for a camshaft drive. The sprocket features a density of 7.0 gm/cm 3 and a transverse rupture strength of 206 kpsi as well as 119 kpsi tensile and 99 kpsi yield strengths. P/M gave BorgWarner Engine Group Morse Tec Europe S.r.l., Milan, Italy a cost savings of more than 10%.
A 16-part assembly from Burgess-Norton Mfg Co., Geneva, Ill., blew away the Innovative Functional Assembly competition. The grand-prize-winning free-wheel steering-system axle assembly for a snowblower weighs in at 5.9 lb and consists of a stamped steel frame, bronze and plastic bearings, and a wrought steel axle. The assembly functions as an on-demand operator-controlled differential traction system. The P/M parts range from single-level to intricate multilevel designs. All parts are close to net shape and have a density range of 6.7 to 6.8 gm/cm 3 . Secondary operations are limited to vibratory deburring and honing. P/M halved part cost compared to machine castings and wrought materials.