The Influence of Temperature and Metal Pairs on the Scuffing of a Commercial Oil

Abstract

A modified type of 4-ball machine—a ball running on three asymmetrically placed pegs—allows the scuffing behaviour of a commercial extreme pressure lubricant to be investigated. Particular emphasis has been placed on the reactivity of the steels used as test specimens and their position relative to the contact. The constant failure temperature hypothesis is found to be obeyed only under certain well defined conditions. It is shown that the friction-temperature behaviour measured at slow speed can be correlated with scuffing results at high speed. Little evidence is found to support the minimum film thickness failure criterion.