Effects of Asperities in Elastohydrodynamic Lubrication

Optical interferometry was used to study rough surfaces under lubricated point contact. Three dimensional “asperities” of chromium were sputtered onto a steel ball which was run against a smooth glass plate under both rolling and sliding. The experimental results were compared with the various published theories. The film thicknesses found in sliding are different from those observed in pure rolling, which are nearly equal to the theoretical values. Film thickness collapse occurred when the central film thickness/half asperity height ratio (λ ratio) reached a critical value.