A preliminary investigation on the use of the pin-on-disc test to simulate off-brake friction and wear characteristics of friction materials

Abstract

During off-brake driving, some unwanted contact between the brake pads and the rotating discs may occur, thus inducing inefficient fuel usage and additional environmental pollution. This paper addresses the frictional behavior of 5 commercial low-met and NAO friction materials dry sliding against a cast iron counterface disc, under low contact pressures, typical of off-brake driving. In the investigated conditions, kinetic and static coefficient of frictions (COFs) were found to be independent from the contact pressure. The static COFs were all found to be around 0.2, whereas the kinetic COFs were found to be higher in the low-met materials with respect to the NAO materials and they were found to be roughly independent from the contact pressure. The results were explained with reference to the adhesive theory of friction, highlighting the paramount role of the Fe-oxides embedded in the friction layer.