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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MPIF Awards of distinction
A three-level range sleeve used in a differential in a Magna Powertrain NPG 226 transfer case took the Ferrous award of distinction. Keystone Powdered Metal Co., St. Marys, Pa., forms the 2-lb part via warm compaction to a density of 7.2 gm/cm 3 . Magna Powertrain USA Inc. (formerly Magna Drivetrain of America Inc.), East Syracuse, N.Y. , is the first to use P/M in a transfer-case differential for GMC Envoys and Chevrolet Blazers. The part links the transmission and the wheels, transferring power to the rear wheels when in two-wheel-drive mode and into all four wheels when in four-wheel drive. All three splines are net formed along with the pointed teeth. Properties include ultimate tensile and yield strengths of 18 kpsi and a typical 40 HRC hardness. P/M dropped part cost more than 30%.
A second ferrous award of distinction went to Pennsylvania-based, GKN Sinter Metals-Emporium, for a differential cap made for the Chrysler Group. Two caps go into the differential gear assembly in the rear axle of Jeep Grand Cherokees, Wranglers, Liberties, Dakotas, and Durangos. It's the first time that a proprietary machinable P/M material was used in a high-volume, automotive differential cap. GKN assembles the parts with cast iron housings and simultaneously bimetal machines inside diameter bores and threading. The part is made to a density of 6.7 gm/cm 3 in the arch. It has an ultimate tensile strength of 70 kpsi, an elongation of 3%, a fatigue endurance limit of 26 kpsi, and a 75 HRB apparent hardness.
GKN uses a patented Z-loc technology that reportedly improves subassembly alignment between the differential cap and the case. P/M let GKN eliminate five secondary operations previously needed on the casting it replaced.
Asco Sintering Co., Commerce, Calif., won the stainless steel award of distinction for a safety cam made for Buck Knives, Post Falls, Idaho. The cam operates in several knife models using Buck's new ASAP one-handed quick-release system for opening the knife blade; the blade cannot open until the safety cam has been released. Asco devised an innovative tool to form the complex net-shape part from 410 stainless steel. The cam sports a 6.5 gm/cm 3 density, a 23 HRC hardness, and ultimate tensile yield strengths of105 and 90 kpsi, respectively.
FloMet LLC, DeLand, Fla., and its customer SDS Ormco, Orange, Calif., garnered the first of two Injection Molding awards of distinction for a Damon 3 Molar Buccal Tube system used in orthodontic braces. The system consists of 32 MIM brackets and two MIM slides made from 17-4PH stainless steel. The parts are heat treated and have an ultimate tensile strength of 185 kpsi, yield strength of 160 kpsi, 7% elongation, and range in hardness from 38 to 42 HRC. The tube system was first introduced in the all-metal Damon self-ligating orthodontic appliance.
MIMflow Technologies LLC, Euclid, Ohio, and its customer, The Star Dental div. of DentalEZ Corp., Lancaster, Pa., earned the second Injection Molding award of distinction for a manifold used in a handheld fiber-optic swivel dental system that delivers air, water, and fiber-optic light simultaneously into a patient's mouth. The complex 17-4PH stainless-steel part has a density of 6.7 gm/cm 3 and features 19 critical dimension callouts that require tolerances be held to ±0.003 in. or less. The part has seven cores including a 0.023-in. core that must be drilled in the green state. That's because it features a compound plane to the centerline that could not be machined as a postsintering operation due to the small diameter of the drill. MIM replaced a machined part that had yielded a useable rate of only 60%.
A kinematic optical mount used in laboratory equipment won an Innovative Functional Assembly award of distinction. Precision Powdered Metal Parts Inc., Pomona, Calif., forms the 316L stainless-steel part that is fabricated to a density of 6.4 gm/cm 3 with a yield strength of 25 kpsi. The optical mount holds a mirror lens that
directs and deflects a laser beam with two 100 pitch-thread adjustments. The assembly replaces a machined aluminum part. Secondary operations include deburring, drilling, tapping, and blasting with glass beads to improve appearance.
Engineered Sinterings & Plastics Inc. (ESP), Watertown, Conn., won a second Innovative Functional Assembly award of distinction for a lower-arm assembly used in a proprietary application in the publishing and copying industry. The assembly consists of six complex P/M parts; plastic, laser cut, steel plate, and screw machined parts; and standard purchased components. The four P/M steel parts are made to a minimum density of 6.8 gm/cm 3 and are steam treated. The two 316 stainless-steel parts are made to a typical density of 6.6 gm/cm 3 . The assembly was originally designed with all of the components either machined or stamped. ESP designed and built the plastic and P/M molds, machining fixtures, and inspection and true-position fixtures.