1. Feel the bearing quality through the surface
In the process of selling bearings, I found that many customers said that as long as the bearing surface is bright, it is of good quality, which is wrong. Testing Quality The brightness of the bearing surface should be a kind of black brightness. The reasons for this black brightness are whether the steel used by the bearing meets the standard, its grinding process and the cutting fluid used, mainly the first two.
2. Is the chamfer bright
The chamfer of the bearing does not determine theTesting quality of the bearing, but reflects the processing method of the bearing. The chamfering is black, which means that after quenching and other heat treatment, the hardness of the bearing is increased. Some people think that the chamfering is black, which is not completely processed. This is a misunderstanding.
3. The integrated cage is better than the two bodies. Although the new process uses the integrated cage, it only saves materials, Testing Quality and the performance of rotation is worse than the two bodies.
In general, the service life of the bearing is related to three factors: one is the quality of the bearing itself. Testing Quality The second is the use environment. The third is the installation method.
We all know that many imported bearings will fail. Many users of imported bearings have this situation. Why? Testing Quality The failure of imported bearings has become a new problem for us. We need to find all ways to solve this problem. What is the solution?
This problem is so difficult to solve. Of course, it is difficult to solve. Imported bearings are easy to fail Testing Quality This is a common problem when we use imported bearings After the bearing runs for a period of time, it is necessary to check whether there are problems, especially whether it fails. Today I will tell you the failure classification of imported bearings.
Contact fatigue failure refers to the failure of bearing working surface under the action of alternating stress. Testing Quality Contact fatigue spalling occurs on the working surface of the bearing and 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, Testing Quality forming deep spalling. Deep spalling is the fatigue source of contact fatigue 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. Testing Quality 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 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 Testing Quality in the complete loss of lubrication function, resulting in the loss of rotation accuracy and even normal operation of the bearing. 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. Abrasive wear refers to the wear caused by the relative movement of Testing Quality 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 imported bearings, which often causes furrow like scratches on the working surfaces of bearings.
Hard particles or foreign matters may come from the Testing Quality 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 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 metal may be locally melted, and the force on the contact surface will tear the local friction Testing Quality welding point from the substrate and increase the plastic deformation. This cyclic process of adhesion tear adhesion constitutes adhesive wear. Generally speaking, slight adhesive wear is called scratch and severe adhesive wear is called bite.
The main reasons for the fracture failure of imported bearings Testing Quality are defects and overload. When the external load exceeds the material strength limit and causes the part to break, it is called overload fracture. Overload is mainly caused by sudden failure or improper installation of the host.
Defects such as microcracks, shrinkage cavities, bubbles, large foreign objects, Testing Quality overheated tissue and local burns of bearing parts will also cause fracture at the defect during impact overload or severe vibration, which is called defect fracture.
It should be pointed out that in the manufacturing process of bearings, 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, Testing Quality and the control must still be strengthened in the future. But generally speaking, most of the bearing fracture failures are overload failures.
During the operation of imported bearings, due to the influence of external or internal factors, the original matching clearance is changed, the accuracy is reduced, Testing Quality 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 Testing Quality are the main causes of clearance change failure.