For the radiator, although water cooling is a very effective way of heat dissipation, but the higher cost expenditure, still can not shake the important position of air-cooled heat dissipation. But compared with water-cooled radiators, the most headache of air-cooled radiation is the huge noise generated by the fan when it works.

Of course, there are many factors that determine the noise level of heat dissipation fans, including fan speed, fan size, fan dynamic balance, use environment and so on. One of the most important factors is the type of fan bearings, such as hydraulic bearings, ball bearings, magnetic bearings and other diverse, so what impact do these bearings have on the silence and life of fans? What's the difference?

Ball bearings are generally recommended for fan bearing systems, because the life of cooling fans usually depends on the reliability of their bearings. Ball bearing systems have been proved to be efficient and low heat generation. Ball bearings are rolling friction, rolling by metal beads, small contact surface, small friction coefficient; while oil bearing is sliding friction, large contact surface, long-term use, oil will volatilize, bearing easy to wear, friction coefficient, later noise, short life. In addition to large ventilation volume and high pressure, the reliability of fans with good quality is also very important. The bearing form used by fans is very important here. High-speed fans always use Ball bearing, while low-speed fans use low-cost oil bearing. Oil bearing fans use only one bearing; while ball bearing fans need two bearings, single ball bearing, which is "1 Ball + 1 Sleeve", still contains oil bearing components. More advanced than single ball bearings are double ball bearings, namely Two Balls. The life of oil bearing is generally 10 000 hours, single ball bearing is 30 000 hours, double ball bearing is more than 50 000 hours (ambient temperature is set below 25 C).

Oily bearings used in fans are sintered from copper-based powder. Oily bearings need lubricating oil to reduce sliding friction. The lubricating oil is made of lithium-based grease and special oil. With a long time running, the oil in the bearing will evaporate and become dry, the friction coefficient will increase, the fan operation will be affected, there may be abnormal sound, slow speed or even no rotation phenomenon. Ball bearing replaces sliding friction by rolling friction, which has small friction coefficient and overcomes the shortcoming of easily changing friction coefficient. Therefore, it has strong running stability and long service life.