A: 

Lubrication can play the following roles in rolling bearings:

The formation of oil film increases the contact area and reduces the contact stress. Eliminate frictional heat, reduce the temperature of the bearing working surface, and prevent burns. Reduce the friction between metals and slow down their wear. Plays the role of dust, rust, and corrosion prevention. To ensure that the rolling bearing can operate normally for a long time under high-frequency contact stress, and to extend the fatigue life, the role of grease in the bearing is quite large.