Improved cryogenic frictional properties of thrust ball bearings in liquid nitrogen through PTFE cages and dimple-type textures

To improve the working performance of thrust ball bearings in liquid nitrogen, self-lubricating PTFE cages and surface-textured raceways are introduced into the bearings. Circular dimple-type textures are generated by the laser process. The frictional characteristics of a full-steel bearing and a bearing with a PTFE cage are tested and compared at first on a self-developed cryogenic rotating-type tribometer. The micrographs of the worn surfaces are analyzed together. Then, the surface-textured raceways are employed into the bearings with PTFE cages. The influence of different circular dimple diameters of the textures on frictional performance is analyzed. Finally, an influence mechanism of the PTFE cage and surface textures on the cryogenic frictional performance of thrust ball bearings is proposed based on the experimental results.