AGMA 04FTM4

In earlier studies, surface roughness had been shown to have asignificant influence on gear pitting life. Within a relativelysmall range of surface roughness (Ra = 0.1 – 0.3micron), gearpitting life asmeasured by the FZG pitting test decreases as gearsurface roughness increases. This inverse relationship between gearsurface roughness and pitting life is well understood in the field.To determine whether this inverse relationship is applicable to awider range of surface roughness values, we have conducted apitting study using gears whose surface roughness ranges from0.1 -0.6 micron. The results were not completely expected. The studyshows that themicropitting area is radically larger when the gearsurface roughness is close to the upper limit of the range studied.Plasticity index, which approaches a value of around 3.7 for therougher gear surface, appears to be responsible for the formationof such large micropitting area. At the same time, the formation ofa pit is also greatly delayed. Not only is the pitting lifesignificantly longer, but the initiation of pits can occur near thepitch line. This paper discusses how high surface roughnessintroduces a wear mechanism that delays the formation of pits.

Edition:

04

Published:

10/01/2004

Number of Pages:

12

File Size:

1 file , 6.8 MB