Direct observations of a micropit in an elastohydrodynamic contact

A hard steel roller from a disc tester which had an isolated micropit and associated cracks on its surface was pressed against a glass plate and subjected to a range of lubricated, rolling–sliding conditions, with the objective of observing the effect on the distribution of film thickness in an EHL contact. The results show a remarkable interaction between the micropit, the direction of sliding and the thickness of the elastohydrodynamic film. Fluid expulsion into the cavitated region can be observed as the micropit emerges from the contact.