Three Main Factors Of Linear Bearing Failure

According to different materials, linear bearings can be divided into metal linear bearings and plastic linear bearings, and linear bearings are used with quenched linear transmission shafts. A system of infinite linear motion. Due to the point contact between the load ball and the quenched drive shaft, the allowable load is small, but when moving in a straight line, the frictional resistance is small, the precision is high, and the moving speed is fast. However, in the process of use, it often leads to the failure of the linear bearing.

1. Wear failure

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

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

Abrasive wear refers to the intrusion of foreign hard particles or hard foreign matter or abrasive particles into the metal surface between the working surfaces of the linear bearing and the wear caused by the relative movement of the contact surfaces, which usually causes furrow-like scratches on the bearing working surface. Hard particles or foreign matter may come from the inside of the main engine, or other adjacent parts from the main engine system may be sent into the interior of the linear bearing through the lubricating medium.

Adhesive wear refers to uneven stress on a friction surface due to tiny bumps or foreign objects on the friction surface. When the lubrication condition is severely deteriorated, the local frictional heat can easily lead to local deformation and frictional micro-welding of the frictional surface. In severe cases, the metal on the surface may melt locally, and the force on the contacting surface will tear the localized friction welded joint from the substrate and increase the plastic deformation. This stick-tear-stick cycle 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 the failure caused by the alternating stress on the working surface of the linear bearing. Contact fatigue spalling occurs on the working surface of linear bearings, often accompanied by fatigue cracks. First, it occurs at the alternating shear stress below the contact surface, and then diffuses to the surface, forming different exfoliation shapes, such as pitting or pitting exfoliation, exfoliating into small flakes, called shallow exfoliation. Due to the gradual expansion of the exfoliated surface, it often extends to deep layers and forms a deep exfoliation. Deep spalling is the fatigue source of contact fatigue failure.

3. Fracture failure

The main causes of fracture failure of linear bearings are defects and overload. When the applied load exceeds the strength limit of the material and causes the part to break, it is called overload fracture. The main reason for overloading is the sudden failure of the host or improper installation. When shock overload or severe vibration occurs, defects such as microcracks, shrinkage cavities, air bubbles, large foreign objects, overheated tissues and local burns of bearing parts will also cause fracture at the defect, which is called defect fracture.

It should be pointed out that during the manufacturing process, linear bearings can correctly analyze whether the above-mentioned defects exist through the re-inspection of raw materials, the quality control of forging and heat treatment, and the instruments in the process control, and the control needs to be strengthened in the future. However, generally speaking, 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 3D coordinate measuring equipment.