A Pin-on-disc Study of the Tribological Properties of Polyoxymethylene (POM) Gear Materials

Polyoxymethylene (POM) is now widely used as a gear material due to its excellent mechanical properties. There have been several studies on the tribology of POM however most of them focused solely on the material itself without integrating practical applications. This study investigates the tribological properties of POM-POM combinations in conjunction with the application of POM gears. Using a pin-on-disc machine, we simulate the sliding part of gear meshing. The influences of contact pressures (40 and 50 MPa), sliding speed (0.1 and 0.5 m/s), and lubrication on the tribological performance of POM pin sliding against POM disc was studied. The results showed that grease can reduce adhesion between sliding surfaces and effectively improve the tribological performance of the POM-POM combination. The friction coefficient decreases with increasing contact pressure which is consistent with existing models of the frictional behavior of polymer-polymer systems. The wear coefficient exhibits contrasting relationships with increasing contact pressure at high and low velocities. Because the wear mechanism changes from predominantly abrasion at low velocity to adhesion-peeling off at high velocity. The friction and wear coefficients both decrease with increasing sliding velocity. The specific mechanisms of the influence of different lubrication conditions, pressures, velocities, and PV values on friction and wear are described and discussed throughout the paper.