To reduce costs, "Cooling Fan Manufacturer" will consider a single miniature ball bearing fan, the so-called single ball bearing, sliding friction and rolling friction hybrid approach, a ball bearing plus an oil bearing the way it's rotor and stator that before lubricated with ball, and with oil, it overcomes the short oil bearing life, running instability problems, "Cooling Fan Manufacturer" rising costs are extremely limited, life can reach 40,000 hours, the drawback is the noise increases after joining the ball, large as 6CM above specifications DC fan is you can use this program, because his speed is relatively low, bearing volume is relatively large, usually with 830, but for "Cooling Fan Manufacturer", in the general speed of 7000 rpm or more, and bearings are used, high-precision ball bearings 520 and relatively coarse oil bearing often have different core issues, the high fan speed if different cores will cause miniature fan stuck phenomenon, or the emergence of friction sound.