Three Main Factors Of Linear Bearing Failure

According to different materials, linear bearings can be divided into metal linear bearings and plastic linear bearings. Linear bearings are used with hardened linear transmission shafts. Infinite linear motion system. Due to the point contact between the load ball and the hardened drive shaft, the allowable load is very small, but when moving in a straight line, the friction resistance is small, the precision is high, and the moving speed is fast. However, during use, it often leads to the failure of linear bearings. What factors will cause the failure of linear bearings?

1. Wear failure

Wear failure refers to the failure caused by the relative sliding friction between the surfaces, which causes the continuous wear of the metal on the working surface. IKO linear bearings and continuous wear will gradually damage the parts in the linear bearings, and eventually lead to the loss of linear bearing dimensional accuracy and other related problems. Wear will affect shape changes, increase the fit clearance, change the shape of the working surface, and may affect the lubricant or cause the lubricant to be contaminated to a certain extent, resulting in a complete loss of lubrication function, which will cause the linear bearing to lose rotation accuracy and even fail to work properly.

Wear failure is one of the common failure modes of various bearings. According to the wear form, it can be divided into common abrasive wear and adhesive wear.

Abrasive wear refers to the wear caused by the invasion of foreign hard particles or hard foreign objects or abrasive particles into the metal surface between the working surfaces of the linear bearing and the relative movement of the contact surfaces, which usually causes plow-shaped scratches on the working surface of the bearing. The hard particles or foreign objects may come from the inside of the host, or other adjacent components from the host system may be sent into the inside of the linear bearing through the lubricating medium.

Adhesive wear refers to the uneven stress generated on the friction surface due to tiny protrusions or foreign objects on the friction surface. When the lubrication condition deteriorates seriously, local friction heat can easily lead to local deformation of the friction surface and friction micro-welding. In severe cases, the metal on the surface may melt locally, and the force on the contact surface will tear the local friction weld joint from the substrate and increase plastic deformation. This cycle of adhesion-tear-adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called wear, and severe adhesive wear is called bite.

2. Contact fatigue failure

Contact fatigue failure refers to failure caused by alternating stress on the working surface of the linear bearing. Contact fatigue spalling occurs on the working surface of the linear bearing, often accompanied by fatigue cracks. First, it occurs at the alternating shear stress below the contact surface, and then spreads to the surface, forming different peeling shapes, such as pitting or pitting peeling, peeling into small flakes, called shallow peeling. Due to the gradual expansion of the peeling surface, it often extends to the deep layer and forms deep peeling. Deep peeling is the fatigue source of contact fatigue failure.

3. Fracture failure

The main causes of linear bearing fracture failure are defects and overload. When the applied load exceeds the strength limit of the material and causes the parts to break, it is called overload fracture. The main cause of overload is sudden failure of the host or improper installation. When impact overload or severe vibration occurs, defects such as microcracks, shrinkage holes, bubbles, large foreign matter, overheated tissues, and local burning of bearing parts can also cause fractures at defects, which are called defect fractures.

It should be pointed out that in the manufacturing process, linear bearings can correctly analyze whether the above defects exist through raw material re-inspection, quality control of forging and heat treatment, and instruments in process control, and control needs to be strengthened in the future. However, in general, the common failure of linear bearing fracture is overload failure. At present, linear bearings are more and more widely used in equipment or special machinery industries, such as electronic equipment, food machinery, packaging machinery, medical machinery, printing machinery, textile machinery, machinery, instruments, robots, tool machinery, CNC machine tools, automobiles and digital three-dimensional coordinate measuring equipment.