Selection of effective hardened case depth of gears based on the tooth failure mode

ObjectiveThe depth of the hardened layer of gears is a significant factor influencing on strength and load-carrying capacity of gears. Modern research shows that different failure modes of gears require different effective hardened case depths. The traditional design of the hardened case depth often only considers the relation between the hardened layer and modulus, does not fully consider the influence of gear service environment, performance requirements and failure mode, and does not truly reflect the theoretical connotation of the hardened case depth. [Analysis] Taking the carburized and quenched gear as an example, the domestic and foreign literature and standards on the effective hardened case depth was summarized. The design method of the effective hardened case depth under different failure modes of gears was given, and the recommended value of the best hardened case depth was given.