Failure analysis of the hottest bearing I

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Bearing failure analysis (I)

bearing is a precision mechanical basic component. With the rapid development of science and technology, customers have higher and higher requirements for the quality of bearing products. It is important for the manufacturer to provide high-quality products that meet the standards and meet the service performance of the host, but it is more important to use the bearings correctly. In recent years, the author has been engaged in the technical work of special bearings for motorcycles, and often encountered such problems, that is, the appearance of these high-performance aluminum alloys is qualified after testing, but the bearings are stuck after installation or have early stalling failure during use. It mainly shows that the rotation is stuck, the working face is seriously peeled off, and the cage is seriously worn, even twisted and broken. The analysis of the failure results shows that there are not many quality problems belonging to the bearing itself, most of which are caused by improper installation and use. Therefore, the author believes that it is necessary to make a superficial review on the common failure modes and mechanisms of bearings, in order to play a role in attracting jade

I. bearing failure mechanism 1 Contact fatigue failure

industry insiders pointed out that in recent years, the treatment and recycling of waste plastics. Contact fatigue failure refers to the failure of the working surface of the bearing under the action of alternating stress. Contact fatigue spalling occurs on the working surface of the bearing and is often accompanied by fatigue cracks. It first occurs at the maximum alternating shear stress below the contact surface, and then extends to the surface to form different spalling shapes, such as pitting or pitting spalling, which is called shallow spalling. As the spalling surface gradually expands, it tends to expand to the deep layer, and {todayhot} forms deep spalling. Deep spalling is the fatigue source of contact fatigue failure. 2. wear failure

wear failure refers to the failure caused by the continuous wear of the metal on the working surface due to the relative sliding friction between the surfaces. Continuous wear will cause gradual damage to bearing parts, and eventually lead to loss of bearing dimensional accuracy and other related problems. Wear may affect the shape change, the increase of fitting clearance and the change of working surface morphology, may affect the lubricant or make it polluted to a certain extent, resulting in the complete loss of lubrication function, thus making the bearing lose the rotation accuracy and even fail to operate normally. Wear failure is one of the common failure modes of various bearings. According to the wear forms, it can be divided into the most common abrasive wear and adhesive wear

abrasive wear refers to the wear caused by the relative movement of the contact surface between the bearing working surfaces due to the extrusion of foreign hard particles or hard foreign matters or wear debris on the metal surface. It often causes furrow like scratches on the bearing working surface. Hard particles or foreign matters may come from the inside of the host machine or from other adjacent parts of the host system and are sent into the bearing by the lubricating medium. Adhesive wear refers to the uneven stress on the friction surface due to the micro bulge or foreign matter on the friction surface. When the lubrication condition is seriously deteriorated, local friction generates heat, which is easy to cause local deformation of the friction surface and friction micro welding. In serious cases, the surface metal may be locally melted, and the force on the contact surface will tear the local friction welding points from the substrate to increase the plastic deformation. This cycle of adhesive tearing and adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called scratch, and severe adhesive wear is called bite. 3. fracture failure

the main causes of bearing fracture failure are defect and overload. When the external load exceeds the material strength limit and causes the part to break, it is called overload fracture. The overload is mainly caused by sudden failure or improper installation of the host. The micro crack, shrinkage cavity, bubble, large foreign matters, overheated structure, local burn and other defects of bearing parts will also cause fracture at the defect during impact overload or severe vibration, which is called defect fracture. 3. The fixture equipped with the machine shall be coated with anti rust oil for storage;. It should be pointed out that during the manufacturing process of bearings, the factory re inspection of raw materials, the quality control of forging and heat treatment, and the processing process control can correctly analyze whether the above defects exist through instruments, and the control must be strengthened in the future. But generally speaking, most of the bearing fracture failures are 98.07 overload failures

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