Gear-making value and efficiency results from having the fewest number of operations performed successfully in a synchronous manner with little or no work in process between operations.
Heat treating of gears is performed to achieve the necessary wear resistance and bending strength. A hardened outer layer on the gear flanks resists wear and scuffing as the mating gears slide in and out of mesh with one another. Additionally, surface hardness delays the occurrence of initial pitting and slows or minimizes the progression rate of pitting. Bending strength is dramatically improved when the root and flank area of the gear teeth are hardened. Most gear designs require root hardening, because heavy loads are generally being transferred (Fig. 1). Residual compressive stresses at the surface correlate to bending strength and fatigue life. Root bending crack propagation and other mechanical failures can be avoided with proper gear heat treatment.