Effect of EHL film thikness distribution on the initial running -in under mixed lubricating condition

The following assumption is assumed to be correct, the surface asperities begin to contact when the sum of two contact surfaces roughness exceeds the minimum oil film thickness between these two surfaces. Further, this concept is applied to the rolling fatigue life design of gears and rolling bearings. However, there is no experimental verification of this concept To verify this concept, pure sliding tests were conducted using a roiling ball on a static plate, and the initial contact position was confirmed within the lubricated contact area. The surface roughness of the static plate was set between the minimum oil film thickness and the thicker oil film thickness found at the central contact area. Initial contact traces were compared with calculated oil film thickness distributions without taking surface roughness into account. Results obtained as follows. (1) The initial contact patterns on the plates closely matched the calculated oil film thickness distribution patterns. (2) It is thought that initial contact begins in near the position of minimum film thickness. (3) It is thought that there is no problem with using the ratio of surface roughness to minimum oil film thickness for rolling contact fatigue life design of gears and rolling bearings.