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1 contact fatigue failure
Contact fatigue failure means the bearing surface by alternating the role of stress arising from failure. Contact fatigue spalling occurred in the bearing surface, often accompanied by fatigue crack, the first contact surface from the following maximum shear stress generated at alternating, extend to the surface and then peeled off to form different shapes, such as point-like as pitting or peeling pitting, peeling said sheet into small shallow peeling. Since the gradual expansion of the surface spalling, and often extended to the deep, forming deep peeling. Deep contact fatigue spalling is the source of fatigue failure.
2. Wear failure
Wear failure refers to the relative sliding between the surface of the working surface due to friction wear and tear resulting metal continuously fail. Continuous wear will cause damage to the bearing parts gradually, and eventually lead to the loss of dimensional precision bearings and other related issues. Wear may affect the change in shape, with the gap increasing and working surface morphology changes that may affect the lubricant, or it reaches a certain level of pollution caused by lubrication complete loss of function, thereby bearing the loss of rotational accuracy and even can not operate normally. Kinds of bearing wear failure is a common failure modes, can generally be divided according to wear the most common form of abrasive wear and adhesive wear.
Abrasive wear between the working surface TIMKEN squeeze means hard particles or hard foreign objects or debris in the metal surface and the contact surface wear caused by relative movement, often resulting in the bearing surface of the scratch-like furrow. Hard particles or foreign matter may come from within or from the host system to host other adjacent parts are made inside the bearing lubricating medium feeding. Adhesive wear due to friction surface means microscopic bumps or objects so that the friction surface uneven force, a serious deterioration in the lubrication conditions, due to local friction and heat, could easily lead to local deformation and friction friction surface micro welding, seriously melting the metal surface may be partial, local friction contact surface of the weld force from the substrate increases tearing plastic deformation. This adhesion - tear - constitute a cyclic process of adhesion adhesive wear, in general, a slight adhesive wear called abrasions, severe adhesive wear is called occlusion.
3 Failure
TIMKEN fracture failure was mainly due to two factors defects and overload. When the applied load exceeds the material strength limit and cause parts breakage called overload fracture. The main reason is the host overload sudden failure or improper installation. Bearing parts of the micro-cracks, shrinkage, bubbles, large foreign debris, overheating, burns and other organizations and local defects in shock overload or severe vibrations will cause the fracture defect, called a defect fracture. It should be noted that, bearing in the manufacturing process, the raw material into the plant reinspection, forging and heat treatment quality control, process control instrument can be correctly analyzed by the existence of the defect, the control must be strengthened in future. But in general, bearing fracture failure usually occurs mostly overload failure.
4 clearance changes fail
TIMKEN at work, due to external or internal factors, with the gap so that the original change, reduced accuracy, and even lead to "bite" is called clearance changes fail. External factors such as excessive interference, installation not in place, the temperature rise caused by the amount of expansion, instantaneous overload, internal factors such as residual austenite and residual stresses in an unstable state and so is the resulting change in clearance causes of failure.
TIMKEN bearings equipment for regular maintenance, operation and external parts replacement bearings TIMKEN be dismantled for inspection, necessary in order to determine whether the second TIMKEN bearing parts can be used again and record the use of the good in the bad. But also to carefully investigate and document split down TIMKEN bearings and appearance of the situation. In order to understand and investigate the remaining amount of lubricant, sampling after a good wash to TIMKEN bearings.
Second, check the TIMKEN bearing raceway, rolling surface and the mating surface of the situation and the state of wear of the cage and other signs of damage and anomalies in particular, to observe the raceway running track. Determine the bearing can be used again, to consider the extent of bearing damage, machine performance, the importance of operating conditions, inspection cycles and then later decide.
Test results, if found TIMKEN bearing damage and abnormal situation, please follow identify the reasons for the phenomenon of bearing damage, develop countermeasures. In addition, test results, if there are several flaws words below, TIMKEN bearings can not be used again, you need to replace the bearings.
1 raceway, rolling rust and have scars.
2 rolling surface, rolling on and playing a significant indentation marks.
3 inner or outer diameter surface creep on the outside diameter.
4 overheating discoloration powerful.
4 sealed bearing grease seals and dust damage to severe.
5 inner and outer rings, rolling elements, cage cracks and any one of them will be fragmented.
6 inner and outer rings, rolling elements of any one of a release.
7 raceway, ribs, rolling a significant injury card.
8 cage badly worn or loose rivets terrible.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| 7009CDB NSK | 45 | 75 | 16 |
| 7009ADB NSK | 45 | 75 | 16 |