CERAMIC BALL, BALL BEARING, MOTOR WITH BEARING, HARD DISK DEVICE, POLYGONAL SCANNER AND METHOD FOR PRODUCING CERAMIC BALL

摘要

PROBLEM TO BE SOLVED: To provide a ceramic ball excellent in wear resistance and capable of preventing noise and vibration even when used as a bearing ball used in a hard disk drive or the like operated at high rotational speed. SOLUTION: The ceramic ball is characterized in that in the observation of the surface of the ceramic ball, a magnetic inclusion is not seen or in the case where a magnetic inclusion is seen, when the interval between circumscribed parallel lines having the maximum interval among circumscribed parallel liens not cutting the inside of the visible outline of each particle which appears on the observed surface is defined as dmax, the size dmax of the magnetic inclusion is <=20 μm. The ceramic ball is excellent in wear resistance and prevents noise and vibration even when used as a bearing ball for HDD(hard disk drive) or for a polygonal scanner.