The Anatomy of a Micropitting-Induced Tooth Fracture Failure - Its Causation, Initiation, Progression and Prevention

摘要

Micropitting has become a major concern in certain classes of industrial gear applications, especially wind power and other relatively highly loaded, somewhat slow-speed applications, where carburized gears are used to facilitate maximum load capacity in a compact package. While by itself the appearance of micropitting (Fig. 1) does not generally cause much perturbation in the overall operation of a gear system, the ultimate consequences of a micropitting failure can, and frequently are, much more catastrophic. Micropitting is most often associated with parallel axis gears (spur and helical), but the authors have also found this type of distress when evaluating damage to carburized, hardened and hard-finished spiral bevel gears. This paper presents a discussion of the initiation, propagation and ultimate tooth fracture failure mechanism associated with a micropitting failure. The subject is presented by way of a discussion of detailed, destructive metallurgical evaluations of several micropitting failures that the authors have analyzed on both parallel axis and bevel gears.