The lubricant can reduce friction; it also prevents the wear and corrosion, to prevent the contamination of the solid and liquid bearing. Theoretically, a well-oiled bearing’s life under ideal working conditions can be reached permanent. Of course, in fact this can not be realized, but correctly lubricated bearings will reach their longest life.

If a protective film formed between the sliding surfaces of the bearing layer, even in the case of the heavy load, it can avoid the occurrence of metal friction. Rolling bearings generally are based on the existing or grease lubrication, in some special examples, using solid lubricant on imported bearings is better.