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 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) however, 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 the discussion of detailed destructive
metallurgical evaluations of several example micropitting failures that the authors have analyzed on both
parallel axis and bevel gears.