Mating surface The surface finish of the mating component has a major effect on the performance of the bearing. Surface roughness should ideally be 32 microinches (0.8 Ra). Suitable materials for shafts, thrust faces, etc., would be hardened steels or stainless. Hard chrome plated steel surfaces cause high wear rates under certain conditions, and burnishing or other surface finish treatments should be considered as an alternative. The minimum hardness suggested is Rockwell 45C. The main criteria is that the mating surface should be free from cutting edges. Journals or thrust faces should be free of lubrication grooves or holes.