Study of Orientation Effects of Grooves on the Film Thickness in Hydrodynamic Lubrication

For better understanding of the effects of surface irregularity orientation on lubrication behaviors, a custom-built test apparatus was used. By a moving transparent disc and a stationary fixed-incline slider with different surface groove patterns, the film thickness of hydrodynamic lubrication was measured to range from about one hundred nanometer to several tens of micron. Numerical calculations were also carried out under the experimental conditions. The results indicated that the load-carrying capacity, as well as the film thickness, is closely related to the orientation angle. For PST (partial surface texture)-type grooves at parallel gap condition, LGS (longitudinally grooved slider) has higher film thickness than TGS (transversely grooved slider) in most cases for both experimental and numerical results. All optimal convergence ratio for each grooved pattern is smaller than that (convergence ratio K = 1.2) of the classical smooth slider. Grooves slotted along the entrainment direction have a big oil reserving capacity, and the side leakage can be reduced to a large extend.