The 2006 Powder Metallurgy Design Excellence Awards, sponsored by the Metal Powder Industries Federation (MPIF), recognized makers of automotive engine and transmission parts for demonstrating the benefits of powder metallurgy (PM).
A PM aluminum camshaftbearing cap made by Metal Powder Products Company's Washington Street Div., St. Marys, Pa., for General Motors Powertrain, Pontiac, Mich., took the grand prize in the automotiveengine category. Only two caps span each cam pair in the dualoverheadcam V6 engines in the Cadillac CTS, SRX and CTX, Buick LaCrosse and Rendezvous, and Saab 9-3. MPIF claims this is a first.
Made to a net shape, the part has a tensile strength of 17,000 psi (117 MPa) and hardness ranges from 85 to 90 HRH.
Choosing PM over an alternative manufacturing process, such as die casting, saves an estimated 50% in costs by eliminating preassembly machining, MPIF claims. PM caps need only one line-boring step during installation.
Stackpole Ltd., Carrier Systems Div., Ont., Canada, won the automotive transmission grand prize for a planetary gear output carrier. The carrier contains three steel PM parts — two spiders and a one-way clutch plate — weighing a total of 8.85 lb (4 kg).
The parts are sinter-brazed into the Le Pelletier planetary gear output carrier, which contains two separate decks of pinion gears. It is the first threepiece carrier designed and made for powder metallurgy. The carrier is used in GM's new Hydra-Matic 6L80 six-speed rear-wheeldrive automatic transmission. It debuted in the 2006 Corvette, Cadillac STS-V and XLR-V, and will be in several 2007 GM SUVs with the Vortec 6.2-liter V8 engine. The parts, formed to a minimum density of 6.8 gm/cm3, have an ultimate tensile strength of 65,000 psi (448 MPa) and 85 HRB hardness.
Metaldyne Corp., Plymouth, Mich., won the award of distinction in the engine category for a new fracture-split camshaft cap made for MWM International, Sao Paulo, Brazil. Several diesel engines, including 2.8, 3.0 and 4.2-liter engines in several truck models, use the steel cap. The 3.0-liter engine contains five caps adding 3.85 lb (1.75 kg) of PM per engine. As the first low-density PM part using fracture-splitting technology, the design eliminates almost 60% of machining time and the expense of locator bushings. The cap is made to a density of 6.8 gm/cm3. Mechanical properties include yield strength of 62,785 psi (433 MPa), tensile strength of 81,200 psi (560 MPa), fatigue strength of 25,375 psi (175 MPa), and a minimum 80 HRB hardness.
PMG Ohio Corporation, Dayton, won the award of distinction in the automotive-transmission category for a steel one-way clutch race. Chevrolet, Pontiac, and Saturn automatic transmissions use the high-strength part.
The PM race undergoes a proprietary surface-densification process on the part's complex, noncylindrical geometry. Surface densification offers a cost-effective alternative to conventional forging, powder forging, or broaching a steel tube. The process ensures full density on the cam surface. The race's minimum bulk density is 7.4 gm/cm3. Contact fatigue strength is more than 524,000 psi (3,615 MPa), and tensile fatigue strength is 111,000 psi (765 MPa). These values match forged, heat-treated steel.
Secondary operations performed on the part include the drilling of six oil holes and turning counterbores. The race passed severe validation testing, indicating a B10 life of 521,000 cycles at a torque value of 230 lb-ft (312 Nm).
The awards were presented at the MPIF Automotive Suppliers luncheon during the SAE 2006 World Congress.