With fast development of electronic and computing technologies and methodologies in the last 20 years, the speed controlling technique applied in the electrical motor industry had great improvement. For precise CNC machinery, numerous wide-range speed regulated DC motors were replaced by permanent magnet synchronous brushless AC motors, particularly in robots and mechanical arms.

To maintain motors at proper operating condition, there are several crucial components require regular maintenance. Bearings, certainly to say, should be the top of the importance, which coupling most mechanical operations. As such a critical element, its material, accuracy,rotating speed, working temperature and the load capability have significant impacts on the equipments’ overall performance and referred service life. For the reasons, more and more customers started moving their eyes from regular bearings to high-speed, high-precision, high corrosion-resistant, low noise and long service life miniature bearings.