1. Contact fatigue failure
Contact fatigue failure refers to the material fatigue failure caused by the action of alternating stress on the working surface of the bearing.
A common form of contact fatigue failure is contact fatigue spalling. Contact fatigue spalling occurs on the working surface of the bearing, often accompanied by fatigue cracks. It first occurs from the maximum alternating shear stress below the contact surface, and then expands to the surface to form different spalling shapes, such as pitting or pitting spalling. In small flakes, it is called shallow exfoliation. Due to the gradual expansion of the peeling surface, it will slowly expand to the deep layer, forming deep peeling. Deep spalling is the fatigue source of contact fatigue failure.
2. Wear failure
Abrasion failure refers to the failure caused by the continuous wear of the metal on the working surface caused by the relative sliding friction between the surfaces.
Continued wear will cause gradual damage to the bearing parts and eventually lead to loss of bearing dimensional accuracy and other problems. Wear failure is one of the common failure modes of various bearings, which can be divided into abrasive wear and adhesive wear according to the wear form.
Abrasive wear refers to the wear caused by the squeeze of foreign hard particles or hard foreign matter or wear debris on the metal surface between the working surfaces of the bearing and the relative movement of the contact surfaces, often causing furrow-like scratches on the working surface of the bearing.
Adhesive wear refers to the uneven stress on the friction surface due to microscopic protrusions or foreign matter on the friction surface. When the lubrication conditions seriously deteriorate, due to local friction and heat, it is easy to cause local deformation of the friction surface and friction micro-welding, which can be serious. When the surface metal may be partially melted, the force on the contact surface will tear the local friction welding point from the substrate and increase the plastic deformation.
3. Fracture failure
The main causes of bearing fracture failure are defects and overload. When the applied load exceeds the strength limit of the material and causes the part to fracture, it is called overload fracture. The main cause of overload is the sudden failure of the host or improper installation. Defects such as micro-cracks, shrinkage cavities, bubbles, large foreign matter, overheated tissue and local burns in bearing parts can also cause fractures at the defects during impact overload or severe vibration, which is called defect fracture.
It should be pointed out that during the bearing manufacturing process, instruments can be used to correctly analyze whether the above-mentioned defects exist during the factory re-inspection of raw materials, forging and heat treatment quality control, and processing process control. But generally speaking, most of the bearing fracture failures that usually occur are overload failures.
4. Corrosion failure
Some rolling bearings will inevitably come into contact with water, water vapor and corrosive media during actual operation. These substances will cause rust and corrosion of the rolling bearings. In addition, the rolling bearing is also affected by micro-current and static electricity during operation, causing current corrosion of the rolling bearing.
Rust and corrosion of rolling bearings will cause pit rust, pear-shaped rust on the surface of the rings and rolling elements, pit rust with the same spacing between the rolling elements, and overall rust and corrosion. Eventually cause the failure of the rolling bearing.
5. Failure of clearance change
During operation of rolling bearings, due to the influence of external or internal factors, the original fitting clearance changes, the accuracy decreases, and even "seizing" occurs, which is called clearance change failure. External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc.; internal factors such as retained austenite and residual stress in an unstable state are the main reasons for clearance change failure.