Why is the motor bearing noisy?

Bearings are essential for mechanical operation, but bearings also have their own shortcomings that can not be overcome. Bearing is one of the sound sources that produce mechanical noise. So why are bearings noisy?

The rolling bearing is composed of rolling body, cage, bearing ring and other parts. When the bearing rotates, the collision between the rolling body and the cage will bring noise; When the bearing roller enters and exits the load zone inside the bearing ring, there will be sliding friction, which will also bring noise; The surface roughness of the bearing roller and raceway can not be completely smooth, which will bring noise; If there is grease inside the bearing, then the bearing will stir the grease when rolling and will cause noise; With sealed bearings, friction between the seal lip and the sealing surface can also cause noise. Bearing noise caused by the above reasons, regardless of whether the bearing is faulty, will exist to some extent, almost inevitable.

In addition, when the bearing fails, there may be bearing noise caused by the fault, and the reasons are complex and not one column.