The Metal Powder Industries Federation, Princeton, N. J., held its annual Design Excellence competition in conjunction with the 2011 International Conference on Powder Metallurgy & Particulate Materials. The organization awarded prizes for innovative powder-metal (PM) parts in several categories, including hand tools/recreation, aerospace/military, hardware/appliances, medical/dental, off-highway, industrial motors/controls and hydraulics, and automotive transmissions, chassis, and engines.
The grand prize in the automotive transmissions category went to GKN Sinter Metals LLC, Auburn Hills, Mich., for the carrier and one-way rocker clutch assembly it made for Ford Motor Co., Dearborn, Mich. The 17-lb PM steel assembly, used in Ford’s Super Duty TorqShift six-speed automatic transmission, combines the cage, spider, carrier plate, and rocker plate into a sinter-brazed subassembly, then adds a cam plate that is doubled-pressed and double-sintered to a density of 7.3 gm/cm3, an ultimate tensile strength of 170 ksi, and a mean tempered hardness exceeding 40 HRC. The assembly required tooling and press development as well as durability and fatigue testing. Using PM costs an estimated 20% less than competitive processes.
GKN Sinter Metals also took the automotive-chassis grand prize for a differential bearing adjuster made for American Axle & Manufacturing, Detroit, Mich. The diffusion-alloyed PM steel part preloads bearings on the GMT 900 rear differentials in GM’s Tahoes and Yukons. It has 6.8-gm/cm3 density, 155-ksi transverse rupture strength, 63-ksi yield strength, and 90-HRB hardness. The design replaces a machining-intensive casting and saves $320,000/year in production costs for the two models.
Cloyes Gear & Products Inc., Paris, Ark., earned the award of distinction in the automotive engine category. Its intake sprocket and exhaust gears accept torque from the timing chain for General Motors Korea’s 2.0 and 2.2-liter diesel engines. The gears are warm compacted so the teeth have a minimum density of 7.2 gm/cm3. The carburized-finished part has 161-ksi yield strength, 55-ksi fatigue limit, and 74-HRA hardness. Going to PM saves the company 8.5 lb of machining waste over wrought steel for the gear set.
Aerospace and military
The grand prize for aerospace and military components went to Capstan California, Carson, Calif., for a gravity-sintered porous bronze filter made for Chase Filters and Components, Newport News, Va., and its medical and emergency breathing devices. The fluted filter’s large surface area gives it a higher flow rate and more dirt-holding capacity. A molded-in retention feature eliminates secondary operations and saves money over a previous stainless-steel design.
Megamet Solid Metals Inc., Earth City, Mo., received the aerospace/military award of distinction for a nickel-steel metal-injection-molded (MIM) rear rifle sight. The 7.5-gm/cm3, 55-ksi ultimate-tensile-strength part was made for Yankee Hill Machine Co. Inc., Florence, Mass., to use on its sporting and military rifles such as the AR-15, M4, and M16. The part’s close tolerances and complex geometry required elaborate tool design.
Hand tools and recreation
A 420-stainless-steel arrowhead for hunting large game won the grand prize in the hand tools/recreation category for Parmatech Corp., Petaluma, Calif. The MIM part, made for Optek Precision Tooling Ltd., Mississauga, Ont., and called the 300Xtreem broadhead, has a thin, straight blade for targeting accuracy. A molded-in external thread lets arrowmakers attach the arrowhead to a shaft. Its final density is 7.7 gm/cm3 and its hardness is 48 to 52 HRC. MIM costs 50% less than machining the blade from stainless-steel bar stock, and the only secondary operation now is sharpening the arrowhead.
Indo-US MIM Tec Pvt. Ltd., Bangalore, India, took home the award of distinction in the hand tools/recreation category for a 17-4PH stainless-steel hammer that’s part of a multipurpose utility tool for Leatherman Tool Group, Portland, Oreg. The MIM part performs five of the tool’s 27 functions, has a formed density of 7.5 gm/cm3, yields at 158 ksi and at least 6% elongation, and is heat treated to a hardness of 35 to 40 HRC. Secondary operations include threading two tapped holes, age hardening, glass-bead blasting, and blackening.
A second award of distinction in this category went to Webster-Hoff Corp., Glendale Heights, Ill., and its customer ACCO Brands Inc., Lincolnshire, Ill., for a steel cam and bushing. The cam transfers power to the cutters of a manual paper-hole-punching machine, and the bushing supports the shaft. Both parts have 6.7-gm/cm3 density, 120-ksi ultimate tensile strength, and 27-HRC apparent hardness after forming to net shape, sinter-hardening, and tempering. The cam is vibro finished and treated with oil. The customer saved $410,000/year over machining.
Hardware and appliances
The grand prize in the hardware/appliances category went to a copper–steel outer-hub exit spindle found in electronic door locks made by ASCO Sintering Co., Commerce, Calif., for Ingersoll Rand Security Technologies’ (Carmel, Ind.) Schlage brand. The spindle rotates to engage a standard lock when a code or electronic-card reader is activated. Its density is 7.7 gm/cm3, and it has 95-ksi ultimate tensile strength, 8% elongation, and 90-HRB hardness. The PM process lowered energy use by 90% and let the company make use of 95% of the materials, as opposed to only 45% used when it was machined from a wrought blank.
Burgess-Norton Mfg. Co., Geneva, Ill., earned the award of distinction in this category for a steel crimp retainer in a gas-flow-regulating valve for commercial-refrigerator compressors. The part has at least 7.1-gm/cm3 density, 150-ksi yield strength, and 74-HRA hardness. Secondary finishing operations include soft machining of three gas holes in the counterbore, carburizing, quenching, tempering, and hard turning to form the counterbore diameter and face. The part costs 30 to 50% less than casting or stamping.
Medical and dental
FloMet LLC, Deland, Fla., earned the grand prize in the medical/dental category for an antimagnetic housing cup and lid used in an EMI-shielding audio device. The MIM cup has four thin walls for proper assembly, and the lid fits securely to keep out moisture and foreign matter. The parts have 8.30-gm/cm3 density, 32-ksi yield strength, and 40% elongation. MIM let FloMet combine several parts into a two-part assembly, cut scrap by 40%, and reduce costs.
A 17-PH-stainless-steel MIM retainer brought the medical/dental award of distinction to Kinetics Climax Inc., Wilsonville, Oreg. The complex part, for an articulating stapler/cutter used in endoscopic surgery, is formed to 7.7 gm/cm3, 158-ksi yield strength, and 6% elongation. The MIM process was 25 to 30% less expensive than other manufacturing options.
Industrial motors, controls, hydraulics, and off-highway applications
A PM diffusion-alloyed rotor made by Lovejoy Sintered Solutions LLC, Downers Grove, Ill., won the award of distinction in the industrial motors, controls, and hydraulics category. The 6.95-gm/cm3 steel rotor spins inside an industrial gear pump. It has a yield strength of 55 ksi, is hardened to 89 HRB, and passes a tooth-hub-joint crush test with a break strength over 6,000 lb. The company turns and mills the rotor, then impregnates it with resin to prevent leaks and make it easier to machine. The part costs 22% less than casting or machining rolled bar stock.
Capstan California won the award of distinction in the off-highway category for a net-shape, gravity-sintered bronze filter plate it made for Knorr-Bremse GmbH, Austria, and its commuter-train brake. A graphite mold incorporates a 8.2-mm cross-hole, eliminating a machining operation. The design uses 8.8% less material and costs 27% less than competitive processes.