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A novel approach to the manufacture of high-performance powder metallurgy (P/M) sprockets and gears has been developed. The result is advanced components with a unique combination of properties tailored to the current needs of the marketplace. This dual material or “Duplex” method allows for the selective application of dissimilar yet compatible P/M alloys in order to optimize properties and reduce costs. In the example described, expensive sinter-hardening or induction-hardening materials were used for the teeth of an automotive camshaft timing sprocket, while the core consists of a low density and low cost material. Key advantages of this approach are reduced weight and rotational inertia, increased sound dampening properties, lower cost, and a reduction in the size of the press required for compaction. The paper describes this development and contrasts the advantages to the current manufacturing methods for components of this type.

Virtually all automotive systems are subject to intense commercial, market and legislative pressures to evolve in new directions. The exhaust system is no exception. The relentless drive to: reduce costs, to extend warranty and service life, to respond to customer cosmetic preference for bright metal under hood combined with emission legislation demanding zero leakage stretch the imagination and resourcefulness of the industry. Powder metallurgy (P/M) has a role to play in this regard. The complex and accurate net shape capability and material versatility of P/M provides an attractive combination for several components especially flanges. A hindrance, however, is lack of a materials property database relating to the special properties required for service. High burnt gas temperatures in exhaust systems produce internal corrosion oxidation attack, and stress relaxation of joints while road salt attacks the external surfaces.