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Advanced powder metal technology is capable of producing carburized, low alloy steel bearings and gears that deliver mechanical performance comparable to conventional steel. This quantum leap in PM technology has been accomplished by applying cold work densification to surfaces that require enhanced durability in the application. Using various test methods, core and surface properties are compared for the PM and conventional steel materials; namely tensile, impact toughness, bending fatigue, and contact fatigue. A back to back durability test for automotive manual transmission gears has been used to compare PM gears with conventional steel gears. Test data shows that PM gear teeth can endure equivalent contact stress and, by employing design benefits which are exclusive to PM tooling related gear tooth manufacture, similar tooth loading as conventional gears. PM manufacturing can achieve AGMA 10 gear quality.

Conventional powder metal (PM), at typical press and sinter densities of around 7.0 g/cm3, cannot be considered as a viable manufacturing technology for automotive transmission gears because of deficits in mechanical durability. The durability limitations are mainly a consequence of density restrictions. However, alloying element selection for hardenability and sintering condition selection are secondary but important factors to consider. It is shown that by development of PM densification and alloying technologies, gearing related mechanical properties can be achieved that closely match those of heat treated wrought alloy steels. It is now possible for PM to be considered as a substitution technology for automotive transmission gears. Traditionally, to satisfy stringent durability requirements, such gears are manufactured by costly extensive machining of steel forgings or nodular iron castings.