Mixed lubrication of coated angular contact ball bearing considering dynamic characteristics

A mixed elastohydrodynamic lubrication (EHL) model for a coated angular contact ball bearing is developed by coupling the influence coefficients with the unified deterministic mixed EHL model. Based on the bearing quasi-dynamics analysis, the influences of the surface roughness, coating thickness, and boundary friction coefficient on the mixed EHL performance of the coated bearing are discussed. The results reveal that high surface root-mean-square roughness can be detrimental to bearing lubrication performance and increase the risk of coating failures. Coating thicknesses on the order of a few microns have a limited effect on the contact load ratio, film thickness ratio, and friction coefficient while having a significant effect on the maximum surface tensile stress and interfacial shear stress, especially for high-friction low-speed conditions. A low-friction self-lubricating coating can effectively improve the tribological performance and prolong the service life of the bearing, especially in the bad lubrication state with severe asperity contacts.