Starved Film Thickness: a Qualitative Explanation

Numerically calculated film thickness can accurately predict measured film thicknesses under fully flooded conditions. However, as more detailed information concerning real life applications becomes available, the validity of the “fully flooded” assumption becomes less tenable. Starved films are much thinner than those formed under fully flooded conditions and it is of great practical importance therefore to be able to predict the ensuing lubrication level. Previous researchers have investigated the relation between the position of the inlet meniscus and starved film thickness. This paper combines a hydrodynamic lubrication approach with a physical boundary condition: the oil inlet film thickness distribution on the surface. Three different cases are investigated; a constant and a harmonic oil inlet film thickness distribution, and the effect of repeated passes. The results are compared qualitatively with experimental observations of starved EHL.