Tribological influencing factors on the formation of micropitting on case-hardened gears

Micropitting is a fatigue damage which occurs during the loaded tooth flank contact primarily in the area of negative specific sliding. By micropitting, a notched, crack-affected tooth flank surface is created. This leads to a reduction of the pitting resistance as well as to an impairment of the dynamic and noise behavior of the transmission. In several FVA research projects, the mechanisms of pitting and micropitting has been investigated intensively, both theoretically and experimentally. This article summarizes selected results of the research projects FVA 4591 and FVA 459 II. Firstly, an overview of the primary tribological influences on the formation of micropitting is given. Secondly, a method for the targeted creation of micropitting is described. Finally, selected pitting damages are discussed which were created using gears both impaired and not impaired by micropitting.