1. Fatigue spalling
The inner and outer raceways of deep groove ball bearing and the surface of rolling element both bear the load and roll relatively. Due to the action of alternating load, cracks form at a certain depth below the surface (at the maximum shear stress), and then spread to the contact surface, causing spalling pits on the surface, and finally developing to large spalling. This phenomenon is fatigue spalling. Fatigue spalling will aggravate the impact load, vibration and noise during operation.
2. Wear and tear
Due to the invasion of dust and foreign matters, the relative movement of raceway and rolling body will cause surface wear, and poor lubrication will also aggravate the wear. As a result, the bearing clearance will be increased, the surface roughness will be increased, and the bearing operation accuracy will be reduced, thus the motion accuracy of the machine will be reduced, and the vibration and noise will also increase. For precision mechanical bearings, the wear limit the bearing life.
3. Plastic deformation
When the shaft is subjected to excessive impact load or static load, or additional load caused by thermal deformation, or the invasion of foreign matters with high hardness, dents or scratches will be formed on the raceway surface. This will make the bearing produce violent vibration and noise during operation. Moreover, once there is an indentation, the impact load caused by the indentation will further cause the spalling of the nearby surface.
Corrosion is one of the most serious problems of rolling bearings. High precision bearings may lose their accuracy due to surface corrosion and cannot continue to work. Water, acid and alkaline substances will directly invade the bearing and cause corrosion. When the bearing stops working, the bearing temperature drops to the dew point, and the moisture in the air condenses into water droplets attached to the bearing surface, which will also cause corrosion. In addition, when there is current passing through the bearing, the current may pass through the contact point of raceway and rolling element, which may cause electric spark and produce electric erosion, and form washboard like unevenness on the surface.
Excessive load may cause fracture of bearing parts. Grinding, heat treatment and improper assembly will cause residual stress, and excessive thermal stress will also cause fracture of bearing parts. In addition, improper assembly method and process may cause the bearing ring rib and roller chamfer to fall off.
Under the condition of poor lubrication, high speed and heavy load, the bearing parts can reach a very high temperature in a very short time due to friction heating, resulting in surface burn and gluing. The so-called gluing refers to the phenomenon that the metal on the surface of one part adheres to the surface of another part.
7. The cage is damaged
Due to improper assembly or use, cage may deform, increase friction between cage and rolling element, even make some rolling element stuck and unable to roll, and may also cause friction between cage and inner and outer rings. This damage will further aggravate the vibration, noise and heat, resulting in bearing damage.