Bearing surfaces with isotropic finish

Abstract

A roller bearing has working surfaces, that is surfaces where its rollers and races contact each other, which have extremely shallow irregularities that are nondirectional and thus render the working surfaces isotropic. Moreover, the isotropic surfaces have very low average asperity slopes and likewise a very low plasticity indexes. To derive the high quality working surfaces, the races and rollers are first ground or otherwise mechanically machined to provide the working surfaces with the proper profiles. Then the races and rollers are immersed in a liquid chemical which reacts with the metal at the surfaces and contemporaneously forms a protective coating which inhibits further reaction. Abrading elements within the chemical come against the races and rollers as they are agitated and continuously remove the coating from higher elevations of the working surfaces, so that the chemical continues to react with the metal at those higher elevations. The irregularities diminish to very shallow pits of no particular orientation, thus leaving the working surfaces isotropic. Thereafter, in the absence of the chemical, the protective coating is removed, exposing the high quality working surface. The bearing requires no run in, that is to say, after the initial loading its torque and temperature remain steady at low magnitudes. Moreover, the isotropic surface imparts greater fatigue life.