Why Is The Noise Of The Cooling Fan Increasing After Being Used For A Period Of Time?

After using the cooling fan for a period of time, it will be found that the noise is significantly higher than before. Is this due to the quality issue of the fan itself or other reasons?
In fact, most of this situation is due to the quality issues of the cooling fan itself. There is a structure that is an oil-containing cooling fan, and the bearings are made of copper powder metallurgy. This type of bearing has relatively low accuracy and initially has a quieter sound because lubricating oil is added. Due to the effect of lubricating oil, the friction sound between the shaft core and the bearings during rotation will be relatively small, but as the application time increases, The lubricating oil will gradually decrease or dry up, and the noise will become louder and louder.
The solution to the increasing noise of the cooling fan is to use high-quality bearings, and a common method is to use double ball bearings. This type of bearing is currently recognized as having a long service life and is commonly used by cooling fan manufacturers.