Reduction of NRRO in a Ball Bearing for HDD Spindle Motors (3rd Report, Influence of lubrication on NRRO of a Ball Bearing)

摘要

In this paper, we experimentally analyzed the influence of lubrication for Non Repeatable Run -out (NRRO) of a ball bearing, and proposed the best design for a ball bearing used in HDD spindle motors with regard to NRRO and acoustic endurance. The results are summarized as follows f (1 ) In grease lubrication, NRRO fluctuated in accordance with torque fluctuation caused by grease splush. On the other hand, NRRO fluctuation was not observed in oil lubrication. (2 ) When ceramic balls were used, the acoustic increase was very small even when bearing was lubricated with minute amount of oil. (3 ) It was thought that the best design for a ball bearing used in HDD spindle motors was that the number of balls was 12, the material of balls was ceramic and the lubrication was minute amount of oil.