Patent ID: 7641850

Claim:
A method for net shaping gear teeth of a high performance power transmission gear from a powder metal workpiece, comprising the steps of: (a) heating a powder metal workpiece in the form of a near net shaped gear blank having gear teeth surfaces above its critical temperature to obtain an austenitic structure throughout its surfaces; (b) isothermally quenching the workpiece at a rate greater than the critical cooling rate of its surfaces to a uniform metastable austenitic temperature just above the martensitic transformation temperature; (c) rolling the gear teeth surfaces of the workpiece to a substantially finished outer peripheral profiled gear tooth shape from tooth tip to tooth root on both sides of the gear teeth between opposed dies, each die having an outer peripheral powder metal gear tooth finishing surface that substantially deviates from a nominal involute tooth geometry, the outer peripheral powder metal gear tooth finishing surface being configured to geometrically finish the powder metal surface of each tooth, from tooth tip to tooth root on both sides of the gear tooth, during rolling so that the geometrically finished tooth, from tooth tip to tooth root on both sides of the gear tooth, has dimensional tolerances for power transmission gearing, while holding the workpiece at the uniform metastable austenitic temperature, the gear teeth surfaces undergoing densification, plastic deformation, strengthening and final shaping as a result of the rolling operation; and (d) cooling the workpiece through the martensitic range to thereby harden the surfaces of the gear teeth.