As underlined by SKF’s philosophy, the use of clean lubricants for rolling bearings is essential for obtaining a long bearing life.
Although in the case of grease lubrication, many factors can affect the degree of cleanliness during operation. Utilization of clean grease for the initial lubrication as well as for re-lubrication is always required.
Also in applications where the bearing fatigue life is not critical (e.g. because of very low loads), the need for clean greases can still be extremely important as they contribute significantly to low bearing noise, which is an important requirement for many electric motor applications.