Compared with the water-cooled radiator, the most troublesome aspect of air-cooled heat dissipation is the huge noise generated by the electronic cooling fan when it is working. Of course, there are many factors that determine the noise level of an electronic cooling fan. One of the most important factors is the fan's bearing, including hydraulic bearings, ball bearings, and magnetic bearings.
So what are the effects of these bearings on the mute and service life of the DC cooling fans? What's the difference?
It is generally recommended to use ball bearings for fan bearing systems, because the life of electronic cooling fans usually depends on the reliability of their bearings. Ball bearing systems have been proven to have high efficiency and low heat generation characteristics. Ball bearings belong to rolling friction, rolling by metal balls, with a small contact surface and a small friction coefficient; while oil-bearing bearings have sliding friction and large contact surfaces. After long-term use, the oil will volatilize, the bearing is easy to wear, the friction coefficient is large, and the later noise is louder, the service life is short.
In addition to large ventilation and high wind pressure, reliability is also very important for a cooling fan supplier to produce a good-quality DC cooling fan. The type of bearing used by the fan is very important here as well.
High-speed fans always use ball bearings, while low-speed electronic cooling fans use low-cost oil-impregnated bearings. Oil-impregnated bearing fans only use one bearing; while ball-bearing fans all need two bearings, a single ball bearing is "1 Ball + 1 Sleeve", which still has the composition of an oil-impregnated bearing.
What more advanced than single ball is double ball bearing, namely Two Balls. The life of oil-impregnated bearings is generally 10,000 hours, 30,000 hours for single ball bearings, and more than 50,000 hours for double ball bearings (when the ambient temperature is set below 25°C).
The oil-containing bearings used in electronic cooling fans are made of copper-based powder sintered. The oil-containing bearings need to be added with lubricating oil to reduce the number of 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 dc cooling fan may be affected, abnormal noise may occur, and the speed may be slow or even not rotating happens. The ball bearing replaces sliding friction with rolling friction with 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.