The fan bearing system of cooling fan is mainly divided into sleeve bearing and ball bearing, while ball bearing is divided into single ball bearing and double ball bearing.

Sleeve Bearing

Sleeve Bearing is sintered from a copper-based powder. The use of the sleeve bearing requires lubrication to reduce the number of sliding friction. It can be said that it is the most common bearing technology in the market. Due to its low cost and simple manufacturing, many products, including well-known brands, are still in use.

In the initial use, the running noise is low and the manufacturing cost is low, but this kind of bearing is seriously worn, and its service life is far behind that of ball bearing. Moreover, this kind of bearing has been used for a long time. Due to the oil seal, the lubricating oil will gradually volatilize, the friction coefficient will increase, and the dust will also enter the bearing, the operation of the cooling fan will be affected,which will cause problems such as slow fan speed and increased noise.

In serious cases, the fan eccentricity will cause severe vibration due to bearing wear. When these phenomena occur, either open the oil seal to refuel, or only eliminate and buy new fans.

Single Ball Bearing

Single Ball Bearing(1 Ball +1 Sleeve Bearing) is an improvement on the traditional sleeve bearing. It adopts the mixed form of sliding friction and rolling friction. In fact, it uses one ball bearing with one sleeve bearing to reduce the cost of double ball bearing.

Its rotor and stator are lubricated with balls and supplied with lubricating oil. It overcomes the shortcomings of short service life and unstable operation of oil bearing, and the cost increase is extremely limited.

The single ball bearing absorbs the advantages of sleeve bearing and double ball bearing, and prolongs the service life of bearing to 40,000 hours. The disadvantage is that the running noise increases after adding balls, but it is still less than that of double ball bearing.

Double Ball Bearing

Double Ball Bearing (2 Ball Bearing) belongs to high-grade bearing. It adopts the form of rolling friction and uses two ball bearings. There are several tiny steel balls in the bearing around the axis.

When the fan blade or shaft axis rotates, the steel ball rotates along with it,so that the weight of the whole fan blade rotor rests on the ball bearing and indirectly supported by the spring. Because they are all spheres, the friction between the bearing surfaces is effectively reduced, and the service life of the fan bearing is effectively prolonged.

Therefore, the heat output of the radiator is reduced, and the service life is prolonged, which is about 50,000-100,000 hours (when the ambient temperature is set below 25°C). The disadvantages are that the process is more complicated, which leads to the increase of manufacturing cost and higher noise at the same speed level.

The double ball bearing is embedded in the fan, and the rotating part is not in direct contact with the outside world. Compared with sleeve bearing, double ball bearings have batter anti-aging performance, are suitable for fans with higher speed. They have better sealing performance without oil leakage.

In a sealed environment, the working environment of bearings is relatively stable. Therefore, almost all large-diameter fans of 5000 rpm class use double ball bearing.