Heat treatment is a key and complex factor in gear manufacturing, which greatly affects the performance of each gear in transmitting power or transmitting motion to other components in the assembly. Heat treatment optimizes performance and extends the life of gears in use by changing their chemical, metallurgical and physical properties. These characteristics are determined by considering the geometry of the gear, the power transmission requirements, the stress at different points in the gear under load, the load cycle rate, the type of material, the design of the mating components and other operating conditions.

Heat treatment improves physical properties, such as surface hardness, which imparts wear resistance to prevent simple wear of the tooth and bearing surface; heat treatment also improves the fatigue life of the gear by generating underground compressive stress to prevent high contact stress on the gear teeth. Pitting and deformation. These same compressive stresses can prevent the gear root from fatigue failure due to periodic bending.

Physical properties such as surface hardness, core hardness, surface depth, ductility, strength, wear resistance and compressive stress distribution can vary greatly depending on the type of heat treatment applied. For any given type of heat treatment, the results can be adjusted by changing the process parameters (such as heating source, temperature, cycle time, atmosphere, quenching medium and tempering cycle) to meet specific application requirements.