The spalling at the limit position of the single side of the channel is mainly manifested in the serious spalling belt at the junction of the channel and the retaining edge.The reason is that the bearing is not installed in place or sudden axial overload in the process of operation.

The countermeasures to be taken are to ensure that the bearing is installed in place or to change the outer ring fit of the free side bearing into a clearance fit, in order to compensate the bearing when the bearing is overloaded.

If the installation cannot be ensured in place, the oil film thickness of the lubricant can be increased (to improve the viscosity of the lubricant), or the load of the bearing can be reduced to reduce the direct contact of the bearing.

Symmetric peeling shows that the inner ring is peeling from the surrounding ring, while the outer ring is peeling from the circumferential symmetric position (that is, the short axis direction of the ellipse), mainly because the ellipse of the shell hole is too large or the structure of the two halves of the separated shell hole, which is particularly obvious in the motorcycle camshaft bearing.

When the bearing is pressed into the shell hole with a larger ellipse or the two halves of the separated shell are fixed, the outer ring of the bearing produces ellipse, and the clearance in the short axis direction is significantly reduced or even negative.

Under the action of the bearing load, the inner ring rotates to produce circumferential spalling traces, while the outer ring only produces spalling traces in the symmetric position of the short axis direction.This is the main reason for the early failure of the bearing. The inspection of the failure parts of the bearing shows that the roundness of the outer diameter of the bearing has changed from 0.8um to 27um under the original process control.This value is much larger than the radial clearance value.

Therefore, it can be confirmed that the bearing is working under severe deformation and negative clearance, and the working surface is easy to form abnormal sharp wear and peeling at early stage.

The countermeasures are to improve the machining accuracy of the shell hole or not to use the two-half separation structure of the shell hole as far as possible.

The inclined peeling ring on the working surface of the bearing indicates that the bearing is working in an inclined state. When the inclined Angle reaches or exceeds the critical state, it is easy to form abnormal sharp wear and peeling at early stage.The main reason is because of poor installation, shaft deflection, shaft journal and shell hole accuracy is low.

Measures are taken to ensure the installation quality of bearings and improve the axial runout accuracy of shaft shoulder and hole shoulder, or improve the viscosity of lubricating oil to obtain a thicker lubricating oil film.

The failure of ring fracture is rare and is usually caused by sudden overload.Causes are more complex, such as bearing raw material defects (bubble shrinkage), forging defects (overburning), heat treatment defects (overheating), processing defects (local burns or surface micro-cracks), host defects (poor installation, poor lubrication, instantaneous overload), etc.The ring may be broken by overload impact load or severe vibration.

The countermeasures are to avoid the overload impact load, choose the appropriate amount of interference, improve the installation precision, improve the service conditions and strengthen the quality control in the bearing manufacturing process.