On the Performance of EHL Contacts with Textured Surfaces

The effect of surface patterns created by laser on the running-in and the steady-state behavior of ST37 disk is studied both experimentally and analytically using a mixed-lubrication model. Experiments are conducted using a pin-on-disk apparatus. Circular dimples with a radius of 200 mu m and depth of 30 mu m are textured via a laser on the surface of the disk. The geometry of the dimples is selected based on the optimum size of dimples reported in the literature. The head of the pin is shaped such that the pin and the disk form a line contact configuration. Each experiment was performed using a new contact pair to investigate the running-in as well as the steady-state behavior of textured disks. The results indicate that by means of surface texturing the friction coefficient and wear rate can be reduced by 12-23 and 50%, respectively. The usefulness of the dimples highly depends on the speed, which has a tremendous effect on the film thickness. Increasing the velocity and decreasing the applied load result in a reduction in the wear rate. A parametric simulation study was also performed to gain insight into the relationship between the input parameters such as speed, applied load, and the size of dimples on the film thickness, pressure distribution, and the load-carrying capacity. The model is also able to predict the friction coefficient in the mixed-lubrication regime. Comparison of the friction coefficient values obtained experimentally is found to be in good agreement with the results predicted by the computational model.