What causes fatigue spalling

Fatigue spalling is scale spalling caused by rolling fatigue on the working surface of bearing. When the bearing works, the load on the rolling element and inner ring (or outer ring) is not constant, but changes repeatedly with the operation of the bearing. This load is alternating load; Because the contact area between the rolling element and the inner ring (or outer ring) is very small, the contact stress is very large. At high speed, under the repeated action of huge alternating contact stress, the metal will fatigue.

At first, small cracks are visible at the parts with concentrated stress. Due to the action of lubricating oil and metal corrosion, the cracks gradually expand. When they expand to a certain extent, the surface metal will peel off and form small pits, similar to pitting. When we disassemble and inspect plastic bearings, we often find pitting and metal peeling on the surfaces of inner or outer rings and rolling elements, This is the phenomenon of metal fatigue spalling. If the bearing fatigue spalling occurs after long-term operation, it shall be regarded as natural damage. If it occurs in the middle or early stage of bearing use, it shall be regarded as unnatural spalling. At this time, the cause of spalling shall be found out.

Unnatural spalling unnatural spalling is caused by human factors, which occurs in the middle or early stage of bearing use. The main causes of unnatural peeling are improper selection of bearing type or improper installation. Due to the spalling caused by improper selection of bearing type, early spalling may occur when deep groove ball bearing is selected under large axial load. Spalling mainly occurs in the raceway, which makes the rolling track of the rolling body move towards the ball loading port and roll through the ball loading port, resulting in serious spalling damage to the raceway. The measure to prevent this damage is to reasonably select the bearing according to the working conditions of the plastic bearing.