Outstanding powder metallurgy (PM) parts won awards in the 2007 Powder Metallurgy Design Excellence Awards competition sponsored by the Metal Powder industries Federation (MPIF). The winning parts are examples of advances in conventional press & sinter PM processing, metal injection molding (MIM), and hot isostatic pressing (HIP).
Grand Prize Awards
Stackpole Automotive Gear Division, Mississauga, Ontario, Canada, and its customer Magna Powertrain, New Process Gear Division, East Syracuse, N.Y., received the Grand Prize for a high-precision PM steel clutch hub.
Stackpole selected a special low-cost lean-alloy material to meet strict dimensional-control, compressibility, and durability requirements in a demanding-performance environment. The complex six-level part operates in the clutching system of an active four-wheel drive transfer case in light trucks and SUVs.
The clutching system replaces a manual synchronizer system to allow full-time active control of torque transfer. It facilitates variable torque distribution to the vehicle’s front wheels on the fly. High-temperature sintering provides impressive properties: a minimum density of 7.0 g/cm3, 165,000 psi tensile strength, yield strength of 150,000 psi, and an apparent hardness of 35 HRC. The complex castellated geometry required innovative tooling to precisely control lengths, diameters, densities, weight, and run-out, as well as an even density distribution throughout the part. Annual production exceeds 600,000 parts.
Lawn and garden/off-highway
FMS Corporation, Minneapolis, Minn., and its customer Team Industries, Bagley, Minn., share the Grand Prize for an assembly of six net-shape precision PM parts that make up the forward–reverse actuator assembly in golf cart transmissions.
By changing the electrical switch, the assembly actuates the transmission linkage to engage either forward or reverse gearing. The parts are made to a typical density of 6.9 g/cm3. Most of the parts require heat-treated properties of 120,000 psi tensile strength, 110,000 psi minimum yield strength, 43,000 psi fatigue strength, and a typical hardness of 35 HRC.
While no machining is performed on the parts, secondary operations include zinc plating and vacuum oil impregnation. Team Industries estimates that PM delivered a 50 percent cost savings over the next most competitive fabrication process.
Metal Powder Products–Anaheim, Calif., won the Grand Prize for a 316L stainless steel secure cap cover that is used with two other PM parts in a fire protection locking system. The complex part features large external tabs that are precisely oriented to an internal depressed wave form that allows it to mesh with two other PM parts.
Made to a density of 6.5 g/cm3, the cap cover has a 20,000 psi yield strength, a 55 HRB hardness, and an as-sintered elongation exceeding 20 percent.
The customer subjects the part to a rigorous impact-and-abuse test to prove its integrity against vandals. The three external lugs must withstand the impact of a 10-pound sledge hammer and a torque loading of more than 500 pounds. The main body must be resistant to drilling. The customer realized cost savings of more than 80 percent by choosing PM over conventional machining.
The Grand Prize goes to Megamet Solid Metals Inc., Earth City, Mo., for a trigger guard made by metal injection molding for Modern Muzzleloading, Inc., Knight Rifles, Decatur, Ala. The MIM guard supports the trigger group and hammer in the “quick detachable trigger” mechanism in a 50 caliber muzzle-loading hunting rifle.
Made to a density of 7.4 g/cm3, the 3.1 ounce MIM steel part has an as-sintered tensile strength of 94,250 psi and a 58,000 psi yield strength. The part is held to critical dimensions of +/- 0.005 inches. Secondary operations include: reaming three holes, tapping two screw holes, and deburring. The customer applies the black oxide surface finish and drills one hole because of a design change. Choosing the MIM process provided substantial cost savings.
Flomet LLC, DeLand, Fla., and its customer Ormco Sybron Dental Specialties, Orange, Calif., won the Grand Prize for three parts—bracket, slide, and removable drop-in hook—used in the Damon 3MX self-ligation orthodontic tooth-positioning system.
One bracket and one slide go on each tooth with the hook an option for about five percent of the teeth. The very tiny, intricate parts are made by metal injection molding from 17-4 PH stainless steel powder to a density of 7.5 g/cm3. They have impressive physical properties: a tensile strength of 172,000 psi and yield strength of 158,000 psi. All of the parts are made to a net shape. The customer tumble polishes them and performs a brazing operation before assembly.
Industrial motors/controls and hydraulics
Lovejoy Sintered Solutions LLC, Downers Grove, Ill., and its customer Petrotec–India/Portugal, Gujarat, India, won the Grand Prize for a complicated five-level rotor. The rotor functions as part of an assembly in hydraulic pumps that draw petroleum fuels from an in-ground tank to the above-ground nozzle.
The part has nine legs, each 50 mm long and 10 mm wide, creating a five-to-one aspect ratio. The legs are pressed to a density of 7.1 g/cm3. Made from MPIF F-0005-25 PM material, the rotor has a tensile strength of 33,000 psi, a yield strength of 27,550 psi, and a 56 HRB hardness. Lovejoy performs some machining on the hub and cup. The customer estimates a 30 percent cost savings versus the machined casting used previously.
Other market segments
A dipole cryomagnet end cover fabricated by Bodycote HIP–Surahammar in Sweden for Metso Materials Technology Oy, Finland, for delivery to the particle physics center of CERN, the European Organization for Nuclear Research, Switzerland, won the Grand Prize in this category. The end cover is used in the Large Hadron Collider, the world’s largest and highest energy sub-atomic particle accelerator.
Made from 316LN stainless steel powder, the part is hot isostatically pressed to full density. The superconducting dipole cryomagnets operate in a cryogenic environment at minus 450°F. As HIPed to a near-net shape of 253.5 pounds, the finished end cover weighs 153.3 pounds.
Bodycote incorporated finite element analysis, computer aided design, numerically controlled sheet metal cutting technology and cutting-edge robotic welding and part manipulation to produce the end covers. This resulted in a more than 50 times increase over the typical production rate of fully-dense HIPed PM near-net shapes, an unprecedented breakthrough in productivity. About 2,700 end covers have been delivered to CERN.
The design of the part features several complex configurations. For example, both the inner and outer surface of the broad face is radiused with the inner surface approximately parallel to the outer surface. The exterior of the curved surface has either eight or 10 projections, depending upon which version of the part is produced. The design differs slightly depending on which side of the dipole magnet it is located. The PM HIPed part meets the equivalent mechanical properties of 316LN wrought stainless steel, including internal toughness and high ductility.
Awards of Distinction
Capstan Atlantic, Wrentham, Mass., won the Award of Distinction for an assembly of two parts, called the sprocket assembly–drive and sprocket–driven, used in an SUV transfer case. The three-level sprocket has a precision-machined tooth radius, hub diameter, and tapered inside diameter, as well as a precise involute profile to facilitate a smooth chain roll-off in operation.
Made from a modified MPIF FL-4405 PM material, the parts feature a density of 7.4 g/cm3, a tensile strength exceeding 200,000 psi, an apparent hardness of 45 HRC, and a microhardness of 60 HRC. The sprockets are carbo-nitrided for tooth wear resistance.
Lawn and garden/off-highway
Burgess-Norton Manufacturing Co., Geneva, Ill., won an Award of Distinction for two actuator arms—right-hand and left-hand—used in a zero-turning-radius control system for high-end commercial and residential riding lawnmowers.
The innovative PM arms replaced two six-piece assemblies, eliminating 12 parts and related labor and assembly costs.
The PM lever arms incorporate a bevel gear and stop lug into a lever that controls a hydraulic system. Made from MPIF FC 0208-50 material, the actuator arms have a density of 6.7 g/cm3, a tensile strength of 50,000 psi, and a hardness range of 75 to 100 HRB, providing good wear properties. More than 200,000 of the parts are produced annually.
NetShape Technologies, Inc., Cambellsburg, Ind., has captured the other Award of Distinction in the category for a new differential carrier gear made for Ariens Company, Brillion, Wis.
The part is used in a transmission for the Ariens professional Snothro line of 8.5 horsepower-and-higher snow blowers. The new design improved the drive torque output of the unit by speeding up the pinion and increasing the ratio after the friction disc in the transmission. The gear enables remote locking and unlocking of the differential.
Formed as a net shape to a density of 6.8 g/cm3, the complex five-level part has a minimum tensile strength of 75,000 psi, a transverse rupture strength of 130,000 psi, a yield strength of 90,000 psi, and a fatigue limit of 34,000 psi. Quenching and tempering is the only secondary operation performed on the part.
SSI Technologies, Inc., Janesville, Wis., won the Award of Distinction for PM and MIM parts used in tactical hinge-style handcuffs made by ASP, Inc., Appleton, Wis., a law enforcement products supplier. The handcuffs use 14 PM parts, of which five are different designs—a lock pawl, bow, side and center links, and main links.
Twelve parts are made from three stainless steel materials and two parts are made from MPIF FD-0405-60 steel. The four main links are made by metal injection molding to a minimum density of 7.5 g/cm3 and have a tensile strength of 78,000 psi.
The other parts are processed by conventional or high-temperature sintering. The bow has a tensile strength of 103,000 psi, and has a large 0.090 inch radius in the areas where it touches the wearer’s wrist. These radii had been machined in the previous design. Three modified 316 stainless steel parts and two duplex stainless steel MIM parts make up the linkage assembly. A proprietary and patent-pending design allows the assembly to be swaged together without using rivets. The stainless steel parts meet stringent government corrosion resistance requirements.
PMG Holding, S.A., Mamer, Luxemborg, won the Award of Distinction for a stainless steel camshaft pulley made for Yamaha Marine Co., Ltd., in Japan.
The pulley operates in the timing control mechanism for a 4-stroke 115-horsepower outboard motor. With an outer diameter of 4.36 inches, it is considered large for PM stainless steel. It is made to a density of 6.7 g/cm3 and has a tensile strength of 49,300 psi and yield strength of 21,750 psi.
Successfully producing the large pulley required a special powder-mixing technique of first coating the particles with a liquid binder, followed by the addition of a substantial amount of a special lubricant. These additives were completely removed by precisely controlled vacuum dewaxing. Machining the inner diameter counter bore is the only secondary operation.
Kinetics, a Climax Engineered Materials Company, Wilsonville, Ore., has earned the Award of Distinction for a 316L stainless steel metal injection molded pin shroud made for ArthroCare Corporation, San Juan Capistrano, Calif. The critical part is used in the company’s Opus Magnum Knotless Implant device for arthroscopic surgical repair of torn rotator cuffs. The implant device secures a sutured tendon to the shoulder bone. The pin shroud is implanted into a patient and is critical to the functioning of the rotator cuff surgical procedure.
Made close to a net shape, the MIM pin has a typical density of 7.85 g/cm3, a tensile strength of 78,000 psi, and yield strength of 29,000 psi. Metal injection molding replaced an assembly made by wire-EDMing three parts and assembling them to each other by laser welding. Choosing the single MIM part reduced the customer’s final assembly time by two-thirds, from 15 minutes to just five minutes per unit.
Industrial motors/controls and hydraulics
This final Award of Distinction was captured by Webster-Hoff Corporation, Glendale Heights, Ill., and its customer, Norgren Automotive Inc., Mt. Clemens, Michigan, for a PM aluminum lever block. The part is used in a quick-change vacuum cup system that handles parts and/or materials. Made to a density of 2.45 g/cm3, the multi-level shape has a tensile strength of 16,000 psi and yield strength of 7,000 psi.
Awards were presented during the 2007 International Conference on Powder Metallurgy & Particulate Materials held in Denver, May 13–16 and sponsored by MPIF and APMI International.