How to determine the cooling of the cooling fan is good or bad?

From appearance to choose from the cooling on the cooling fan surface should be overall thick, color is more pure, Especially in black, with the color of the cooling fan is not important) , at the edge of the box leaves no burrs, see the thickness of the heat dissipation dc cooling fan blades ( Thin is very important because it's too easy to break) , with the hand knead frame without too much deformation. Cooling fan functioning later choose cooling dc cooling fan after normal operation, seize the cooling fan feel it vibrate with the hand, and different point of view, the feeling is the same for the cause that the vibration of the cooling fan is very good, if there are vibrations, may produce a total shock, in case some people before a loud sound when the phone is switched on mainly the cooling fan starts shaking. With his hand to stop the cooling dc cooling fan rotation ( Don't put the blade broken) A minute or so, with the hand to touch the blade center feels its temperature, if the high temperature is not qualified to prevent heat dc cooling fan in the die was burned down and cause a fire. Should only hear the wind, Some high speed may have electromagnetic acoustic) , if there are other voice shows its quality is not very good. If heat dc cooling fan speed is not very high as 7 cm cooling fan of no more than 3500 RPM, but the wind that the poor quality of the cooling fan. Coming up from bearing selection for bearing is divided into two kinds of ball bearings and oil bearing. Ball bearing service life is long, the noise is small, but very expensive requirements; The service life of oil bearing a third shorter than ball bearings, in use after a period of time may be some noise ( More than one year) , but the price is cheap. If some ball bearing of the cooling fan with the price of oil price is the same as the cooling fan, explain the ball bearing or out products for the old, don't buy. With each manufacturer of pushing the new bearing ( In addition to the clear oil bearing) Life won't have more than ball bearings, but also in the later use have noise. Watch to select various parameters on the outer packing is to provide the following two parameters for your reference: voltage: 5 v12v24v48v in 7, 8 cm radiator cooling fan speed does not exceed 3500 RPM without other function parameters. Choosing brand from the brand good heat dissipation dc cooling fan means choose quality, so the quality of heat dissipation dc cooling fan is an important guarantee.