Contact fatigue failure refers to the failure of NSK bearing working surface caused by alternating stress. Contact fatigue spalling occurs on the working surface of sliding bearing, which is often accompanied by fatigue cracks.
It first occurs from the large 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 expands to the deep layer, forming deep spalling. Deep spalling is the fatigue source of contact fatigue failure.Three Factors of NSK Bearing Failure
2. Clearance change failure
During the operation of NSK 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.Three Factors of NSK Bearing Failure
3 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 bearing parts, and eventually lead to the loss of dimensional accuracy of sliding 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 bearing loses the 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 be divided into common abrasive wear and adhesive wear.Three Factors of NSK Bearing Failure
Three Factors of NSK Bearing Failure
First of all, the reasonable design and advanced nature of the structure will lead to longer bearing life. NSK Bearings are generally manufactured through forging, heat treatment, turning, grinding and assembly.
The rationality, advanced nature and stability of all the processing technologies will also affect the life of bearings. Among them, the heat treatment and grinding processes that affect the quality of finished bearings are often more directly related to the failure of bearings.
In recent years, the research on the metamorphic layer of the bearing working surface shows that the grinding process is closely related to the bearing surface quality.Three Factors of NSK Bearing Failure
The metallurgical quality of NSK bearing material was once the main factor affecting the early failure of rolling bearing. With the progress of Metallurgical Technology (such as vacuum degassing of bearing steel), the quality of raw materials has been improved. The proportion of raw material quality factor in bearing failure analysis has decreased significantly, but it is still one of the main influencing factors of bearing failure.Three Factors of NSK Bearing Failure
We know that most bearings are generally replaced after damage, but for some NSK Bearings, if the cost is not high, we will choose to repair the bearings.Three Factors of NSK Bearing Failure
Datum transformation combined repair method
Sometimes the deformation of the design datum is too large to be used, so it is necessary to select some other planes as the datum and re integrate the dimension chain at the same time. For example, if the deformation of NSK bearing body is too large, the bearing body should be reprocessed and corrected based on the rotating assembly, and then the assembly dimension chain should be adjusted according to the size of the reprocessed bearing body.
The method of repairing the adjusting ring should be used to detect and repair according to the order of the dimension chain, so as to control the accuracy of the closed ring.Three Factors of NSK Bearing Failure
Benchmark invariant combined repair method
When repairing and adjusting the accuracy of dimension chain, according to the principle of datum coincidence, only one datum plane is selected as the datum, that is, the design datum, while all other action surfaces are repaired based on this plane. This combined repair benchmark is convenient to check the accuracy and reduce the accumulated error. For example, in the repair of variable speed hydraulic coupling, the bearing body is often used as the benchmark.Three Factors of NSK Bearing Failure