July/August 2005

Inventiveness and business nous characterise Montréal award winners

The winning entries in the International PM Design Competition announced at PM2TEC in Montréal showed the industry's technical strengths in no uncertain terms, and once again demonstrated powder metallurgy's powerful abilities to slash production costs…

The 2005 International PM Design Competition sponsored by the Metal Powder Industries Federation has once again highlighted outstanding examples of powder metallurgy's cost savings and engineering benefits. The winners showcased new applications in automobiles, laboratory equipment, electrical devices, dental products, sporting goods, and outdoor power equipment.
BorgWarner Powdered Metals of Livonia, Michigan, and its customer BorgWarner Transmission Systems of Auburn Hills, won the plum grand prize in the ferrous category for its input and third-position outer races used in GM's 4T65-E transmission. The transmission operates in several GM engines-2.5L, 3.0L, 3.1L, 3.4L, 3.8L, and the supercharged 3.8L.

The parts are formed by an innovative tooling system and are selectively densified on the surface of the pocket form to eliminate high wear that can be encountered by the assembly when free-wheeling. The races are heat treated to meet stringent strength and fatigue-life specifications while minimising part distortion.

The inside diameter of both parts has six pocket forms that contain locking pawl and spring elements during operation. The input position outer race has a unique wave form on its outer diameter. The third-position outer race's skirt is split into four quarter-circle arcs the entire length of the skirt. The parts have an ultimate heat-treated tensile strength of 131 000 psi, an impact energy of 12 foot pounds, and 32 HRC minimum apparent hardness. The races are the first production release of a patented BorgWarner pawl-clutch design that replaces a sprag clutch. Manufacture via powder metallurgy provided a 20 per cent cost savings over forged outer races. The parts are produced at a rate of 5000 units daily for each race, or 1.375 million annually.
In the stainless steel category the grand prize was won by a complex 316 stainless steel support cover. It is made by Webster-Hoff Corporation of Glendale Heights, Illinois, and is used in a high-security military application. The cover is made to a net shape, except for deburring. It has a density of 6.5 g/cm3, an ultimate tensile strength of 41 000 psi, yield strength of 34 000 psi, and 59 HRB hardness. During compaction, two levels and the weight of the part are measured every hour for statistical process control. The levels maintain a CPK of 1.33 and the weight is held to within 3 per cent with a CPK of less than 1.0. The flatness and slot width are held to .005 inches.

Metal injection moulding (MIM) specialists Advanced Material Technologies of Singapore are no strangers to success in this competition and this year were back among the prizes, taking the MIM grand prize for a highly complex electrical connector made for Eubiq and used in a plug and adaptor.
The complex part is made from copper powder to a density of 8.8 g/cm3. It has an ultimate tensile strength of 36 000 psi, a yield strength of 8700 psi, and an elongation of 45 per cent. The electrical plug and adaptor that contains the MIM copper connectors is a new product used in the electrical appliance industry. The plug can be engaged anywhere along the power track and is ergonomically designed to make direct contact with it. The electrical adaptor with the MIM copper connectors allows existing three-pin plugs to engage the power track. Using a MIM copper part replaced processes such as stamping, turning, machining, and press fitting, offering the customer a cost saving of more than 20 per cent.

Automotive parts and BorgWarner featured once again as Sinterstahl Füssen GmbH of Füssen, Germany, took the overseas grand prize for a camshaft sprocket used in a 4.0L V-6 engine. The BorgWarner Engine Group Morse Tec Europe Srl of Milan, Italy, is the customer. The net-shape part is made with innovative tooling that utilises three lower and two upper punches. It has a density of 7.0 g/cm3, a tensile strength of 119 000 psi; yield strength of 99 000 psi, and a transverse rupture strength of 206 000 psi. The material is an iron carbon-molybdenum-chromium composition and is the first known application of a chromium-based sinter-hardened material for a camshaft drive. PM offered cost savings of more than 10 per cent.

Burgess-Norton Mfg Co., Geneva, Illinois, won the innovative functional assembly grand prize for a free-wheel steering system axle assembly containing 16 PM parts weighing 5.9 pounds. Used in a snowblower, the assembly consists of a stamped steel frame, bronze and plastic bearings, and a wrought steel axle, and functions as an on-demand operator-controlled differential traction system.

The operator manually activates the system by pressing a hand lever mounted on the handle bars of the machine. The PM parts range from single-level parts to intricate multi-level parts. The clutch pawl is produced to a net shape peripheral geometry that is not practical or economic by other manufacturing or material processes. All parts are close to net-shape and have a density range of 6.7 g/cm3 - 6.8 g/cm3. Secondary operations are limited to vibratory deburring and honing.

The clutch pawl is sinter hardened, which allows oil impregnation. Because the sinter hardened material is quenched in air rather than in a liquid medium, the porosity can be filled with liquid lubricants. PM provided minimum cost savings of 50 per cent over machine castings and wrought materials. Annual volumes of 25,000 to 30,000 assemblies mean the production of more than 400 000 PM parts.

2005 Grand Prize Winners: Left to right, foreground: Support cover and electrical connectors. Middle: Camshaft sprocket. Background: Transmission outer races and snowblower steering assembly.

While the winners were very good indeed, it is hard to detract from the entries that won the runners-up Awards of Distinction.

A three-level steel range sleeve used in a differential in a Magna Powertrain NPG 226 transfer case won an award of distinction in the ferrous category. Made by Keystone Powdered Metal Company of St Marys, Pennsylvania, for Magna Drivetrain of America of East Syracuse, New York, the two-pound part is a link between 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.

This new application for powder metallurgy - a transfer case differential - is used in the GMC Envoy and Chevrolet Blazer. The part is formed by warm compaction to a density of 7.2 g/cm3. All three splines are net formed along with the pointed teeth. Properties include an ultimate tensile and yield strength of 180 000 psi, and a typical 40 HRC hardness. PM offered a cost savings of more than 30 per cent.

The GKN Sinter Metals plant in Emporium, Pennsylvania, won the other award of distinction in the ferrous category for a PM differential cap made for the Chrysler Group and used in the differential gear assembly in the rear axle of the Jeep Grand Cherokee, Wrangler, Liberty, Dakota, and Durango models. Two caps are used in each assembly. This is the first PM differential cap used in a high-volume automotive application. Made from a proprietary machinable material, the part is assembled with a cast iron housing and simultaneously bi-metal machined with an inside diameter bore and threading. The new PM design eliminated five secondary operations previously required on the casting it replaced. The part is made to a density of 6.7 g/cm3 in the arch. It has an ultimate tensile strength of 70 000 psi, an elongation of 3 per cent, a fatigue endurance limit of 26 000 psi, and 75 HRB apparent hardness. Annual production could exceed 1.8 million parts. The part uses GKN's patented Z-Loc® technology, which improves subassembly alignment between the differential cap and the case.

Asco Sintering Company based in Commerce, California, won the award of distinction in the stainless steel category for a safety cam made for Buck Knives of 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. The 410 stainless steel part reflects an innovative tooling design to form its complex net shape. It is made to a density of 6.5 g/cm3, and has an ultimate tensile strength of 105 000 psi. Its yield strength is 90 000 psi and hardness is 23 HRC.

2005 Award of Distinction Winners: Left to right, foreground: Optical mount, knife safety cam, orthodontic tube system and dental manifold. Background: Range sleeve, differential cap and lower arm assembly.

The entries in the injection moulding category could be said to have "embraced" dentistry in their search for perfection. The first, from FloMet LLC of DeLand, Florida, and its customer SDS Ormco from Orange, California, won their award of distinction in the injection moulded category 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 185 000 psi, yield strength of 160 000 psi, 7 per cent elongation and a 38-42 HRC hardness range. The tube system was first introduced in the all-metal Damon self-ligating orthodontic appliance. When in full production, this application will total more than 12 million parts annually. The Damon system shortens adjustment time by dentists.

The other winners here were MIMflow Technologies LLC of Euclid, Ohio, and its customer, The Star Dental division of DentalEZ Corporation based in Lancaster, Pennsylvania. They won the other MIM award of distinction for a manifold used in a hand-held fibre-optic swivel dental system that delivers air, water, and fibre-optic light simultaneously into a patient's mouth. The complex part is made from 17-4PH stainless steel powder to a density of 6.7 g/cm3. It has 19 callouts of critical dimensions allowing a tolerance of +/- 0.003 inches or less. The part has seven cores. The 0.023-inch core is a compound plane to the centre line of the part and could not be machined as a post-sintering operation due to the small diameter of the drill. The part is drilled in the green state. Metal injection moulding replaced a machined part that had yielded a useable rate of only 60 per cent.

And it should not be assumed that a place as a runner-up to the grand prizes betokens a lack of skill or complexity. In the innovative functional assembly category a kinematic optical mount used in laboratory equipment rightly won an award of distinction. Made by Precision Powdered Metal Parts of Pomona, California, the optical mount holds a mirror lens that directs and deflects a laser beam with two 100 pitch-thread adjustments.

The 316L stainless steel part is fabricated to a density of 6.4 g/cm3 and has a yield strength of 25 000 psi. The patented PM assembly replaced a machined aluminum part. Powder metallurgy offered improved precision, aesthetic appearance, and minimal thermal expansion at room temperature. The complex part is deburred, drilled, tapped, and blasted with glass beads to enhance its appearance.

Perhaps less public, but just as functionally effective, the other award of distinction went to a lower arm assembly used in a proprietary application in the publishing and copying industry. It was manufactured by Engineered Sinterings & Plastics (ESP) of Watertown, Connecticut.

It consists of six complex PM parts; plastic, laser cut steel plate, and screw machined parts as well as standard purchased components.

ESP designed and built the plastic and PM moulds, machining fixtures, and inspection and true-position fixtures to produce the assembly to stringent requirements. The assembly is an outstanding example of a family of parts representing different manufacturing processes.

The four PM steel parts are made to a minimum density of 6.8 g/cm3 and are steam treated. The two 316 stainless steel parts are made to a typical density of 6.6 g/cm3.

The assembly was originally designed with all of the components either machined or stamped. PM replaced machined parts, providing outstanding cost savings.