"Micro Cooling Fan" bearing system generally recommend the best selection of ball bearings, fan heat fan because life often depends on the reliability of its bearings, ball bearing system has been shown to have the characteristics of high efficiency and low heat generation. Belong to rolling friction ball bearing, metal beads by rolling contact surface is small, the friction coefficient is small; and "Micro Cooling Fan" oil-bearing sliding friction, a large contact surface, after long-term use, the oil will be volatile, bearing easy to wear, friction coefficient late noisy, short life. In addition to good quality fan ventilation volume, high pressure outside, reliability is very important, bearing in the form of "Micro Cooling Fan" is used in this is very important.