Bearing system of DC fan
The bearing system of electric fans generally advocates the use of ball bearings. Since the life of DC cooling fans usually depends on the reliability of their bearings, the ball bearing system has been proven to have the characteristics of high efficiency and low heat generation.
Ball bearings are rolling friction, rolling by metal balls, the contact surface is small, the friction coefficient is small; while the oil bearing is sliding friction, the contact surface is large, after long-term use, the oil will volatilize, the bearing is easy to wear, and the friction coefficient is large. The noise is loud and the life is short. In addition to the large ventilation volume and high wind pressure, the reliability of a good-quality fan is also very important. The type of bearing used in the DC fan is very important here. High-speed fans always use ball bearings (Ball bearings) while low-speed fans use low-cost oil bearings (Sleeve bearings).
Oil-bearing fans only use one bearing; while ball-bearing fans need two bearings,
Single ball bearing, '1 Ball + 1 Sleeve
More advanced than single ball is double ball bearing, namely Two Balls. The life of oil-impregnated bearings is generally 10,000 hours,
Single ball bearing is 30,000 hours, double ball bearing is more than 50,000 hours (when the ambient temperature is set below 25℃).
The oil-impregnated bearings used in DC fans are sintered from copper-based powder. The oil-impregnated bearings need to be lubricated to reduce the sliding friction. The lubricating oil is made of lithium-based grease and special engine oil. With long-term operation, the oil in the bearing will evaporate and become dry, and the friction coefficient will increase. The operation of the fan will be affected. There may be abnormal noise, slow speed or even no rotation. The ball bearing replaces sliding friction with rolling friction, has a small friction coefficient and overcomes the shortcomings that the friction coefficient is easy to change, so it has strong running stability and a relatively long life.