Three Main Factors of Linear Bearing Failure

Time：2021.01.07  Source：Roller Bearings Suppliers

Overview of Linear bearing

Linear bearing is a kind of linear motion system, used for linear stroke and cylindrical shaft. Because the load-bearing ball is in point contact with the bearing jacket, the steel ball rolls with the least frictional resistance. Therefore, the linear bearing has low friction, is relatively stable, does not change with the bearing speed, and can obtain smooth linear motion with high sensitivity and high accuracy. Linear bearings are widely used in sliding parts of industrial machinery such as precision machine tools, textile machinery, food packaging machinery, printing machinery, etc.

According to different materials, linear bearings can be divided into metal linear bearings and plastic linear bearings. Linear bearings are used together with quenched linear drive shafts. A system of infinite linear motion. Due to the point contact between the load ball and the quenched drive shaft, the load is allowed to be small, but when moving in a straight line, the friction resistance is low, the accuracy is high, and the speed of movement is fast. But in the process of use, it often leads to the failure of linear bearings. What factors will lead to the failure of linear bearings?

1. Wear failure

Wear failure refers to the failure caused by the relative sliding friction between surfaces, which results in continuous wear of the metal on the working surface. linear bearings and continuous wear will gradually damage the parts in linear bearings and eventually lead to the loss of dimensional accuracy of linear bearings 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 make the lubricant be polluted to a certain extent, resulting in the complete loss of lubrication function, resulting in the loss of linear bearing rotation accuracy, and even can not work normally.

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

Abrasive wear refers to the wear caused by the relative movement of external hard particles or hard foreign bodies or abrasive particles invading the metal surface between the working surface of linear bearings and the contact surface, which usually causes furrow-shaped scratches on the working surface of bearings. Hard particles or foreign bodies may come from inside the main engine, or other adjacent components from the main engine system may be fed into the linear bearing through the lubricating medium.

Adhesive wear refers to the non-uniform stress on the friction surface due to tiny bumps or foreign bodies on the friction surface. When the lubrication condition deteriorates seriously, the local friction heat is easy to cause the local deformation of the friction surface and the friction micro-welding.In severe cases, the metal on the surface may melt locally, and the force touching the surface will tear the local friction-welded joint from the substrate and increase plastic deformation. This stick-rip-stick cycle constitutes adhesive wear. In general, mild adhesive wear is called wear, and severe adhesive wear is called occlusion. Need WSBC 22224 E, Click here to learn more.

2. Contact fatigue failure

Contact fatigue failure refers to the failure caused by the alternating stress on the working surface of linear bearings. Contact fatigue spalling occurs on the working surface of linear bearings and is often accompanied by fatigue cracks. First, it occurs at the alternating shear stress below the contact surface and then diffuses to the surface to form different peeling shapes, such as pitting or pitting peeling, peeling into small sheets, known as shallow peeling. Due to the gradual expansion of the exfoliated surface, it often extends to deeper layers and forms deep exfoliation. Deep spalling is the fatigue source of contact fatigue failure.

3. Fracture failure

The main reasons for 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 cause of the overload is a sudden failure or improper installation of the main engine. When impact overload or violent vibration occurs, such as microcracks, shrinkage holes, bubbles, large foreign bodies, overheated tissue and local burns of bearing parts and other defects will also lead to the fracture at the defect, known as defect fracture. Click here to learn more about WSBC 22310 E.

It should be pointed out that in the manufacturing process, the linear bearing can be correctly analyzed whether the above defects exist through the reinspection of raw materials, the quality control of forging and heat treatment, and the instrument in the process control. In the future, the control needs to be strengthened. However, in general, the common failure of linear bearing fracture is overload failure. At present, linear bearings are more and more widely used in the equipment or special machinery industry, 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.

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