1. Surface quenching: The common surface quenching methods of precision reducers are high-frequency quenching (for small-size gears) and flame quenching (for large-size gears).When the hardened layer of surface quenching includes the bottom of the tooth root, the tooth surface hardness can reach 45-55HRC.

　　2. Nitriding: The use of nitriding can ensure that the gear can achieve high tooth surface hardness and wear resistance under the condition of minimum deformation. After heat treatment, no finishing is required, which improves the load-bearing capacity.

　　3. Carburizing and quenching: The carburizing and quenching gear of the precision reducer has a relatively large load-bearing capacity, but the finishing process (tooth grinding) must be used to eliminate heat treatment deformation to ensure accuracy.

　　Carburized and hardened gears are commonly used alloy steels with a carbon fraction of 0.2%-0.3% before carburization. The tooth surface hardness is often in the range of 58-62HRC. If it is lower than 57HRC, the hard surface strength will decrease significantly, and it will be brittle if it is higher than 62HR. Increase.

　　The hardness of carburized hardened gear gradually decreases from the surface of the gear to the deep layer, and the effective carburizing depth is specified as the depth from the surface to the hardness of 5.25HRC.

　　The effect of carburizing and quenching of precision reducer in gear bending fatigue strength not only increases the hardness of the core, but also lies in the residual compressive stress on the surface.It can reduce the stress in the stress zone, so the root part of the tooth cannot be ground when grinding the tooth.