What is the difference between a silent fan and an ordinary fan?

The difference between a silent fan and an ordinary fan lies in the material chosen, speed control and the size of the sound. Silent fan using copper and iron and other materials with good thermal conductivity, in the fan at high speed will not be because of the blade heat and violent tremor, it has a speed control function, can control the speed of the fan in a zone, within a certain speed range of constant work, to avoid noise at high speed operation. Ordinary fans are made of materials with poor thermal conductivity, which make noise at high speeds, and their speeds are not controlled. Usually silent fan time use long time will happen fan blade rotation stiff, this time you need to apply lubricant on the fan spindle, if it is wear and tear caused by the fan blade does not rotate, you need to dismantle and replace the corresponding parts.