1. Contact fatigue failure
　　Contact fatigue failure refers to the working surface of needle roller bearings subjected to alternating stress and failure. Contact fatigue spalling in the SKF bearing working surface, often accompanied by fatigue crack, first from the contact surfaces of the following maximum alternating shear stress, and then extended to the surface flakes of different shapes, such as point-like pitting corrosion or pitting flaking, Peel into small pieces called a shallow flake. Due to flaking surface gradually expanded, and expansion to the deep, forming deep peeling. Deep contact fatigue failure fatigue spalling is the source.
2. Wear failure
　　Wear failure means relative to the surface of sliding friction causes wear of its surface constantly arising out of failure. SKF bearing caused by wear damage gradually, and eventually lead to loss of needle bearing dimensional accuracy and other related issues. Wear can affect the shape change, increased clearance and surface morphology changes may affect the lubricants or lubrication function caused by pollution reaches a certain level and make it a complete loss, so that the loss of running accuracy of the bearing and does not operate properly. Wear failure is one of the common failure modes of all kinds of bearings, worn forms can generally be classified into the most common abrasive and adhesive wear of wear.
　　Abrasive wear of means between the working surface of needle roller bearings packed into external hard particles or hard foreign objects or debris on the surface of metal contact surface wear and tear resulting from the relative movement, furrow-like scrapes caused by needle roller bearing surface. Hard particles or foreign objects may come from inside or from other neighboring parts of the host system from the host internal lubricants to the SKF bearings. Adhesive wear means due to the friction surface micro-bumps or uneven friction force of foreign bodies, lubrication when conditions deteriorated, because of local friction heat, causing friction and local deformation of surface micro-welding and friction, serious metal on the surface may be partial melting, forcing local friction on the contact surface plastic deformation of weld tearing from the substrate increases. This adhesion – tear – cycle constitutes of adhesion of adhesive wear, in General, slightly adhesive wear is known as bruises, severe adhesive wear is called occlusion.
3. Fracture failure
　　Bearing failure due to defects and overload two major factors. When the applied load exceeds the ultimate strength of the material part fracture called the overload fracture. Overload is mainly hosts sudden failure or improper installation. Needle roller bearing parts micro-cracks, shrinkage, bubbles, large defects such as foreign bodies, organizations and local overheating burn shock overload or high vibration is also prone to defects caused by fracture, fracture called defects. It should be noted that SKF bearings in the manufacturing process, raw materials into the plant a re-inspection, forging and heat treatment quality control, process control through the instrument correctly interpreting the defect exists, control must be strengthened in the future. In General, however, most of usually a needle roller bearing failure overload failure.
4. Clearance fail
　　SKF bearing in work, due to the effects of the external or internal factors, so that the original clearance changes, loss of precision, even causing "death" called clearance change failure. External factors such as the degree of interference is too large, the installation is not in place, expansion caused by temperature, instantaneous overload, intrinsic factors such as residual stress and residual austenite in clearance changes caused by instability, which is the main cause of failure.