Common failure analysis of FAG deep groove ball bearing failure

Bearing is as main parts of locomotives, especially traction motor and axis box bearing, plays an important role on security transport .When locomotive is online, once FAG bearing goes wrong, it will led to whole column train not running, and block transport line, especially passenger train is in a malfunction, it causes bigger negative effect. Once locomotive bearing goes wrong, it is difficult to repair. Therefore, preventing and reducing locomotive bearing fault, is important for security transport of locomotive. So, detect the deep groove ball bearings front bearing with security risks, and ensure qualified bearing parts on the train are.

1. Contact fatigue failure

Contact fatigue failure means, bearing surface is subjected to alternating stress and failure. Contact fatigue spalling happens on the FAG bearing working surface, often accompanied by fatigue crack. Firstly occurs from the contact surfaces of the following maximum alternating shear stress, and then extends to surface forming different peeling shapes. Flaking surface is expanding gradually, and tends to spread to deep, forming a deep peeling. Deep spalling is the source of contact fatigue failure.

2. Wear failure

Wear failure means that the bearing surface’ sliding relative friction causes constant wear and tear of its surface and then failure. Constant wear will cause damage of FAG bearing parts gradually, and eventually led to the loss of dimensional precision of deep groove ball bearings and other related issues. Wear can affect the shape change, clearance increased and surface morphology changes, might affect the lubrication function of lubricants, thus the loss of rotational accuracy of bearings and even fail to operate properly. Wear failure is one of the common failure modes of all kinds of bearings, it is generally divided into abrasive wear and adhesive wear by its wear form.

Serious damage of deep groove ball bearing is often not caused by single reason, but under the several combined effects, and in bad running conditions, leads to serious burning loss of FAG bearing, therefore, after accident occurs, it is often difficult to judge what reasons it is due to, So for discussion convenient, i analyze the causes for you from several aspects.

When bearings are used after a period of time, bearing inner ring, rolling elements and cage, outer ring, raceway etc all have certain defects, and injuries, which causes poor lubrication and fever of FAG bearings. Fever for a long time will cause results below:

1, dilution of bearings lubricant

2, accelerate material fatigue and decline in hardness.

Further vicious circle of these reasons accelerates the bearing overheated then burning loss. Significant displacement of the inner ring of deep groove ball bearings, rolling element out-of-round, overheated, eventually are melt together. When the locomotive is running, if found severe heat and smoke, don’t stop it, and maintain to run to the front station. Because overheated bearings are in the melt state at the moment, once stopped to cooling, you can no longer walk then plug the line.