Tribological Investigation of Grease Used in Automotive Constant-Velocity Joints

摘要

High performance greases with separate additive formulations for low friction and wear have been developed specifically for constant-velocity (CV) joints. In this paper, CV joint grease performance was investigated using a versatile pin-on-disk tribometer. 4121-H modified steel disks were procured under the same conditions as an actual CV joint housing and were tested against 52100 steel pins, simulating the roller. To evaluate the effectiveness of CV joint grease, sliding friction and wear under dry and two different types of greases were measured. Experiments under different contacting conditions, such as normal load, contact area, and sliding velocity, were also performed to investigate the friction and wear dependencies. To quantify the surface changes and wear occurring with tribotesting, pin wear lengths and surface profiles of the disk wear tracks were measured. Finally, scanning electron microscopy images of the wear tracks were obtained to investigate the wear mechanisms. It is clear that CV joint grease offers significant improvement of friction reduction and shows stable and convergence tendencies under various contacting conditions.