The winning parts in the MPIF 2003 International Powder Metallurgy Design Competition operate into automotive, power-tool, and other tough applications. Produced through conventional press and sintering, warm compaction, metal injection molding (MIM), and hot isostatic pressing (HIP), these powder metal components replaced die castings, investment castings, forgings, and cold headed and machined parts. Here's a look at the grand-prize winners:
BorgWarner Powdered Metals Inc. and its customer, BorgWarner Inc., TorqTransfer Systems received the grand prize award in the ferrous category for a planetary carrier made up of three sections joined into a single unit. The heat-treated center section of the carrier has an ultimate tensile strength of 138,000 psi, and the end plate has 66,000 psi. The center section has a density of 7.0g/cm³ and the end plates, 6.8g/cm³. Used in GM four-wheel drive torque transfer systems, each carrier section has oil grooves and thrust rings pressed, rather than machined, into its surface. Simultaneous sinter brazing of the three components creates two different pinion windows, eliminating more machining. The 38 fine spline teeth all meet AGMA Class 7 quality. BorgWarner's tests show that the ultimate tensile strength of the P/M carrier is 40% greater than a machined cast iron carrier.
Webster-Hoff Corporation won the grand prize in the nonferrous category for a copper CT bus used in a global circuit protection device. Made for Siemens Energy & Automation, Inc., it has a density of 8.3g/cm³, an ultimate tensile strength of 28,000 psi, a yield strength of 8,600 psi, and a 60 HRH hardness. With a copper hub press-fitted into the bus, this design combines powder metal and machined componets to achieve the final complex shape.
In the injection molding category, Kinetics Inc. and Black & Decker, Inc. took top honors for a low alloy steel MIM blade clamp used in the DeWalt DW303MK professional reciprocating saw. This keyless blade clamp, which is designed to secure the saw blade to the power head, combines two former MIM parts into a single component with a complex net-shape that required a mold with four slides, three cores, and 15 seal off surfaces per cavity. The part also was required to meet stringent precision requirements. The clamp features an ultimate tensile strength of 240,000 psi and a yield strength of 215,000 psi, as well as a 48-51 HRC hardness range. The part is typically formed to a 7.56g/cm³ density.
Metso Powdermet AB and its customer, VM Alliansen II DA, received the grand prize in the advanced particulate materials category for designing an 8.2-ft-long, 11-ton manifold used to collect oil or gas from off shore wellheads. Formed by hot isostatic pressing from a duplex stainless steel material, this manifold replaces a forged manifold that needed more machining and welding.
Stackpole Limited (Mississauga, Ontario, Canada) and its customer, General Motors Powertrain, won the grand prize in the innovative functional assembly category for a variable displacement transmission oil pump. Designed by Stackpole, the pump assembly contains four powder metal parts—a slide, rotor, body, and lid. The assembly's base is an aluminum casting design that mates to the transmission valve body. In addition to designing the product, Stackpole conducted performance tests, including thermal and acoustical testing, along with a 1,000-hour durability trial.
A clamshell housing used in an auto bicycle roof rack won the grand prize in the stainless steel category. Produced by Metal Powder Products for WaterMark Sports, maker of Yakima roof racks, the housing component has a density of 6.5g/cm³, tensile strength of 60,000 psi, a yield strength of 39,000 psi, and a 50 HRB minimum hardness. Powdered 316L stainless steel offered a 65% cost savings over a comparable investment cast and machined part.