1. When the bearing is replaced, the noise of the motor bearing is alleviated. Is this situation necessarily attributed to the bearing?

2. If it is a bearing problem, why some bearings are replaced with new ones, and the noise is still there?

A more complete understanding of these two problems is: replacing the bearing, the noise mitigation may be a problem of the bearing itself, but it may not be. While the noise of bearing replacement still exists, the greater probability indicates that the root cause of bearing noise is not necessarily the bearing itself.

How to understand this conclusion? Let's take a few examples. Of course, there are many factors, so here are just a few.

First, if the problem is with the bearing itself, replace the bearing with no problem, and the noise will naturally be alleviated. The premise is: the bearing to be replaced is a okay bearing. And the method of replacement is correct.

Second, if the process of installing the bearing is wrong, every time the assembly will cause damage to the bearing, then no matter how the bearing is replaced, the noise will always be difficult to eliminate. In addition to the process method, the installation should also consider whether the process method is stable. For example, the same method of knocking (small bearing cold installation) is used to install the bearing. If the bearing is damaged by knocking, the possibility of bearing noise is greatly increased; and when the next bearing is installed, the knocking is relatively light, and the bearing is almost not damaged, so the bearing noise after assembly is naturally small. If this noise difference is attributed to the bearing itself, it is obvious that the root cause has not been found. Over time, the looming bearing noise problem cannot be completely eliminated.

Third, if there is a problem with the shape and position tolerance of the bearing seat or shaft component, the noise may or may not be improved after the bearing is replaced. First of all, if the bearing seat or shaft has a slight shape tolerance out of tolerance, after the first bearing is installed, the inside of the bearing is squeezed and the shape tolerance is out of tolerance, which is likely to cause noise. At this time, if the bearing is replaced and the first bearing is removed, then the first bearing will function as a tool for correcting the shape and position tolerance of the parts to a certain extent. If the slight overrun is corrected, there will be no abnormality in the replaced bearing. Secondly, in the case of severe tolerance out-of-tolerance, even with the "correction" of the previous bearing, the workpiece cannot be adjusted back to the tolerance range. So no matter how you replace the bearing, its noise will still exist.

From the above example, it can be seen that if the bearing itself has a problem, it is effective to replace the bearing. If the problem is not the bearing at all, then replacing the bearing may or may not work. The part that confuses electrical engineers the most is that replacing the bearing is actually effective to some extent, although the ratio is very low. Therefore, this kind of confusing phenomenon makes many engineers mistakenly believe that replacing the bearing is the most direct method with a certain cure rate.

But, but, but, the important thing is said three times. This confusing phenomenon is very harmful. We strongly recommend that all electrical engineers encounter bearing noise problems, it is best to refer to certain ideas to find the underlying cause, rather than simply and rudely replacing the bearing. The symptoms can be cured only when the cause is found.