Experimental simulation of the friction, temperature, and wear distributions for polyamide–steel gear contact using twin-disc setup

Abstract

The friction and wear phenomena in metal–polymer gears are directly connected to the kinematic and load conditions at each location on the flank and face of the tooth. This study investigates the characterization of the distribution of friction, temperature, and wear in the regions close to the pitch point of the contact between the teeth of a polyamide–steel gear. Twin-disc test configuration is considered using polyamide (PA66) disc and nonalloyed structural steel C45 disc with different diameters. The effect of the slip ratios (4%, 12%, 20%, and 28%) were studied at a constant pressure of 34 MPa, and a constant rotational speed of 300 r/min. The contact conditions were controlled with the measurements of the friction coefficient and the two discs surface temperatures using a thermal imager. The results have proven that the wear and friction are closely related to the contact temperature generated by the sliding phenomenon. For points closer to the pitch point, the coefficients of friction and temperature are characterized by a quasi-linear increase with time, and have a similar pattern at both flank and face sides. For these points, the wear increases slowly. For points far from the pitch point, the coefficients of friction and temperature reached a steady state after an initial linear increase. For these points, the friction coefficient and temperature evolutions with the test duration show a gap between the flank and face sides of the tooth. The wear increases dramatically at the flank side, whereas it increases slowly at the face side of the tooth. During the test, a transferred film of PA66 was formed on the steel surface causing the development of adhesive interactions between the contacting discs which increase the friction coefficient and the contact temperature.