The Role of Surface Tension and Disjoining Pressure in Starved and Parched Lubrication

Abstract

The starvation of a rolling, elastohydrodynamic contact has been examined both experimentally and theoretically. It has been shown that starvation occurs at a critical rolling speed which is determined by the rate of flowback of lubricant into the out-of-contact track due to oil/air surface tension forces. Above this speed, however, complete collapse of the oil film in the contact does not occur. Instead a film of approximately 10–20 nm thickness persists even to very high speeds. It has been shown that this behaviour can be explained by considering the flowback into the out-of-contact track due to solid/liquid van der Waals forces. Thus a combination of oil/air and oil/solid surface forces can fully explain the phenomena of starved and parched elastohydrodynamic lubrication.