The effect of surface grooves on film breakdowns in point contacts

Abstract

Surface roughness plays an important role in transition from full to mixed elastohydrodynamic regime. One kind of features appearing on a real rough surface are grooves longer than contact diameter. It has already been reported that these grooves cause a local film reduction or a complete collapse. In this study, a ball-on-disc optical tribometer was used to quantitatively study the effect of grooves on film thickness in a point contact. It was observed that the main dependence on speed, the so-called lift-off curve, generally follows the logarithm function. The effects of build-up material, load, slide/roll ratio and groove geometry are presented. These results were fitted to the analytical description, which enables the estimation of groove effects on point contact lubrication.

Surface roughness plays an important role in transition from full to mixed elastohydrodynamic regime. One kind of features appearing on a real rough surface are grooves longer than contact diameter. It has already been reported that these grooves cause a local film reduction or a complete collapse. In this study, a ball-on-disc optical tribometer was used to quantitatively study the effect of grooves on film thickness in a point contact. It was observed that the main dependence on speed, the so-called lift-off curve, generally follows the logarithm function. The effects of build-up material, load, slide/roll ratio and groove geometry are presented. These results were fitted to the analytical description, which enables the estimation of groove effects on point contact lubrication.