Winners of the 2008 Powder Metallurgy Design Excellence Awards exhibit the cost savings and superior precision that can be attained through use of fine metal powders. Other benefits cited by the Metal Powder Industries Federation (MPIF) are innovative design ability, superior performance and sustainable technology.
A notch/braking plate and a pocket plate used in a mechanical diode one-way clutch saved 70 percent over wrought steel parts. Processes used to make the award winners include high-density gear rolling, warm compaction and metal injection molding. The awards were announced June 11 at the annual meeting of the MP World Congress in Washington, D.C.
The grand prize in the automotive engine category was awarded to a stator used in a variable valve timing (VVT) system in a 1.4-liter engine. Made from a modified iron-copper PM material, the part is formed to a density of 7.0 g/cm3. The stator, featuring five intricate center holes, is a one-piece design that replaced two parts. Very tight tolerances help to minimize any internal oil leakage between the adjoining pressurized chambers.
The PM stator helps reduce fuel consumption and the formation of exhaust gases, as well as improving engine performance, especially torque at low rpms. It has two functions: a spline for the timing-belt pulley and the VVT housing. The award went to PMG Füssen GmbH, Füssen, Germany, and its customer Schaeffler Group Automotive, Hirschaid, Germany. The PM process is said to have offered substantial cost savings despite finishing operations such as sizing, machining, deburring and steam treating.
One of the pioneers of metal injection molding (MIM), Parmatech of Petaluma, CA, won the grand prize in the medical/dental category for a 17-4 PH stainless-steel articulation gear used as part of a surgical stapling unit. The complex design is formed to net shape and requires no finishing operations, one of the key advantages of the MIM process, generally speaking.
The part has tight tolerances and provided a 70 percent cost savings, compared to machining the gear from bar stock. The part has a density of more than 7.65 g/cm3 and an ultimate tensile strength of 130,000 psi, yield strength of 106,000 psi, and a 25 HRC hardness. MIM uses tools that are very much like those used in plastic injection molding. They can range from simple prototype to multi-cavity production tools. Parmatech’s feedstocks typically start with a fine metal or ceramic powder (particle size approximately 1-20 microns) which is incorporated into a fluid binder.
In the hardware and appliances category, the grand prize was awarded to Capstan Atlantic of Wrentham, MA for a powder metal steel gear set used in a high-volume business machine printer. The gear is roll densified to a surface density of 7.8 g/cm3. It has an AGMA quality 10 precision level and the pinion, an AGMA 8 level.
The core density of the gear and pinion is 7.3 g/cm3. The gear-tooth-surface fatigue resistance equals that of a wrought steel 8620 carburized gear. The part, which has opposing helix angles, is formed to net shape, except for hard turning the datum journals. Single pressed, the PM gear replaced two machined gears at a cost savings of more than 40 percent. AGMA standards are established by the American Gear Manufacturers’ Association, Alexandria, VA.