All U.S. Tsubaki sprockets are made from high quality steel. Since chain loadings are evenly distributed over all engaged sprocket teeth, tooth breakage or distortion is not normally a problem. It is seldom necessary to use special high strength material. Sprocket diameter and pitch determine the specific material used.
The hardening process of small diameter, small pitch sprockets is usually a one-step procedure: heat treatment (electrical induction). Large diameter, large pitch sprockets can usually be directly flame hardened. These methods are used to provide a high hardness at the wear areas, plus provide the ability of the tooth to absorb shock loads.
This is accomplished by hardening only the wear area of each tooth while maintaining a ductile tooth core which is tough and resilient. The hubs and bores remain soft to permit reworking. The general guidelines for sprockets are: