Facilitating effective hydrodynamic lubrication for zero-entrainment-velocity contacts based on boundary slip mechanism

The paper presents a new idea of using boundary slip to facilitate hydrodynamic lubrication for zero-entrainment-velocity (ZEV) bearing contacts. The idea entails the bearing contact composed of an oleophobic (slip) and an oleophilic (nonslip) surface. While the nonslip surface drags oil into the ZEV contact, the opposite moving slip surface cannot bring the oil out. The net entrainment of oil thus facilitates hydrodynamic lubrication for the ZEV contact. The idea was validated by ZEV experiments, such that a new retainerless bearing type that incorporates alternately slip and nonslip rolling elements was conceived. The new bearing design fits for wide speed range applications. The optimal characteristics of oleophobic coating required in the new bearing are discussed.