Five things to note when bearing operation

1. Mechanical damage

In severe cases, metal peeling and large-scale messy scratches occur on the contact surface; generally, bearing mechanical damage refers to the presence of grooves of varying degrees on the alloy surface of the bearing. The main reason for the mechanical damage of the bearing when the contact surface damage and the ablation phenomenon coexist is that it is difficult to form an oil film on the bearing surface or the oil film is severely damaged.

2. Bearing cavitation

The surface layer undergoes plastic deformation and cold work hardening. Under the repeated effect of cylinder pressure impact load, the sliding bearing partially loses its deformation ability, gradually forms lines and continues to expand, and then with the fall of wear debris, the loaded surface layer forms holes. Usually, when the bearing is cavitated, pits appear first, and then these pits gradually expand and cause cracks in the alloy layer interface. The cracks expand in the parallel direction of the interface until the fall stops. The main reason for the cavitation of the sliding bearing is that the sudden change of the cross-section of structural elements such as the oil groove and the oil hole leads to a violent imbalance of the oil flow, and the vacuum area where the oil flow is unbalanced forms bubbles, and then due to the increase in pressure, the bubbles collapse and cavitation occurs. Cavitation usually occurs in the high-load area of the bearing, such as the lower bearing shell of the crankshaft main bearing.

3. Fatigue pitting

Bearing fatigue pitting refers to the overheating of the bearing and the excessive bearing clearance due to engine overload. This damage is mostly caused by overload, excessive bearing clearance, or unclean lubricating oil and foreign matter mixed in it. Therefore, when using it, you should pay attention to avoid overloading the bearing and not operate it at too low or too high speed; adjust the engine to a stable state when idling; ensure normal bearing clearance to avoid too high or too low engine speed; check and adjust the working condition of the cooling system to ensure that the operating temperature of the engine is suitable.

4. Bearing alloy corrosion

The chemical impurities (acidic oxides, etc.) in the lubricating oil oxidize the bearing alloy to generate acidic substances. Bearing alloy corrosion is usually caused by impure lubricating oil. It causes the bearing alloy to fall off partially, forming irregular small cracks or small pits. The main reasons for bearing alloy corrosion are improper selection of lubricating oil, poor corrosion resistance of bearing materials, or rough operation of the engine and excessive temperature.

5. Bearing burning

Partial high temperature is caused, and there are small raised metal surfaces directly touching between the journal and the bearing friction pair. In the case of lack of lubrication and poor cooling, the bearing alloy will turn black or partially burn. This fault is often caused by the tight fit between the journal and the bearing; lack of lubricating oil pressure can also easily cause the bearing to burn.