Causes of elevated bearing temperatures in fans

Excessive bearing temperature in fans is one of the primary causes of bearing failure. The main factors contributing to elevated bearing temperatures include the following:

1) Poor lubrication quality. The purpose of lubrication is to prevent direct contact and friction between stationary and moving parts, thereby eliminating friction between solids and liquids. Insufficient lubricant quantity or poor lubricant quality may lead to direct frictional heating between stationary and moving components, or prevent heat dissipation through the lubricating oil, resulting in elevated bearing temperature.

2) Poor assembly quality of rolling bearings. Examples include insufficient preload between the inner sleeve and shaft, or excessive or insufficient clearance between the outer sleeve and bearing housing.

3) Poor bearing quality. In sliding bearings, inadequate scraping and grinding quality, poor contact or detachment of the gold-plated layer; in rolling bearings, cracks, fragmentation, or spalling on the rolling element surface can all compromise the stability and uniformity of the oil film, leading to bearing overheating.   

4) The sealing felt is too tight and generates heat.

5) Excessive bearing vibration under impact loads severely compromises the stability of the lubricating oil film.

6) Insufficient or interrupted cooling water supply to the bearing impedes heat dissipation, leading to elevated bearing temperature.