1. Pitting
Small scattered or clustered pits on the surface of parts, black pinhole pits, with a certain depth, individual or densely distributed. The formation reason is metal surface fatigue. Under the cyclic action of rolling contact stress, micro cracks are formed on the metal sub surface and gradually develop into pits.
2. Scratch
Metal migration on the surface of parts due to sliding friction. It is characterized by surface mechanical damage along the sliding direction of bearing parts and with a certain length and depth. This defect mostly occurs on the working surface of bearing parts. The reason is that the bearing clearance is too small, the lubrication is poor and the impurities in the grease are too large.
3. Crack damage
Damage caused by destruction of metal continuity of bearing parts. It is linear, with variable direction and certain length and depth. Sometimes it is invisible to the naked eye, and there is powder accumulation after magnetization.
