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1. Contact fatigue failure
Contact fatigue failure refers to Analysis And the failure of NTN bearing working surface caused by alternating stress. Contact fatigue spalling occurs on the working surface of NTN bearing and is often accompanied by fatigue cracks.
It first occurs from the large Analysis And 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.
Due to the gradual expansion of the spalling surface, it often Analysis And expands to the deep layer, forming 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 caused by the relative sliding friction between the surfaces. Continuous wear will cause gradual damage to NTN bearing parts, and eventually lead to loss of dimensional accuracy of NTN bearing and other related problems.
Wear may affect the change of shape, the increase of fit 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, so that the NTN bearing loses its rotation accuracy and even cannot operate normally.
Wear failure is one of the common failure modes of various bearings. According to the wear form, it can Analysis And be divided into common abrasive wear and adhesive wear.
Abrasive wear refers to the wear caused by the relative movement of the contact surface due to the extrusion of foreign hard particles or hard foreign matters or wear debris on the metal surface between the working surfaces of NTN bearings, which often causes furrow like scratches on the working surfaces of NTN bearings.
Hard particles or foreign matters may come from the inside of the host machine or from other Analysis And adjacent parts of the host system, and are sent into the NTN bearing by the lubricating medium. Knowledge of NTN bearing accuracy error.
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 conditions are seriously deteriorated, the local deformation and friction micro welding of the friction surface are easy to be caused due to the heat generated by local friction.
In serious cases, the surface Analysis And metal may be locally melted, and the force on the contact surface will tear the local friction welding point from the substrate and increase the plastic deformation.
This cycle of adhesion tear Analysis And adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called scratch and severe adhesive wear is called bite.
There are two main causes of NTN bearing failure: overload and fault. When the external load exceeds the material strength limit and Analysis And causes the part to break, it is called overload fracture. The main cause of overload is the sudden failure or improper installation of the host.
Defects such as microcracks, Analysis And shrinkage cavities, bubbles, large foreign objects, overheated tissue and local burns of bearing parts will also cause fracture at the defect during impact overload or violent vibration, which is called defect fracture.
It should be pointed out that in the manufacturing process of NTN bearing, the presence of the above defects can be correctly analyzed by instruments in the factory re inspection of raw materials, quality control of forging and heat treatment,
and processing process control, and the control must be strengthened in the future. But generally speaking, most of the NTN bearing fracture failures are overload failures.
4. Clearance change failure
During the operation of NTN bearing, due to the influence of external or internal factors, the original matching clearance is changed, the accuracy is reduced, and even “bite” is called clearance change failure.
External factors such as excessive interference, improper installation, expansion caused by temperature rise, instantaneous overload, etc., and internal factors such as residual austenite and residual stress in an unstable state are the main reasons for the change and failure of clearance.
1. If NTN bearing is well lubricated and properly blocks sundries and moisture, it means that the oil seal should not be worn However, when opening the bearing housing, check the bearing and regularly check the oil seal
Check the condition of oil seals near the bearing to ensure that they are sufficient to prevent hot liquid or corrosive liquid or gas from penetrating into the bearing along the axis. If the oil seal is worn, replace it as soon as possible
2. High temperature often indicates that NTN bearing is in abnormal condition High temperatures are also harmful to lubricants in bearings
Sometimes NTN bearing overheating can be attributed to the lubricant of the bearing If the bearing operates for a long time at a temperature of more than 125 ℃, the service life of NTN bearing will be reduced
The causes of high temperature NTN bearing include insufficient or over lubrication, magazine contained in lubricant, excessive load, NTN bearing damage, insufficient clearance, high temperature friction caused by oil seal, etc
3. Check the condition of the machine in operation and monitor it to avoid equipment shutdown