Reasons for bearing noise and measures to be taken

Bearings are key components in rotating machinery, their primary function is to support the rotating shaft while reducing friction to promote smooth motion. Because bearings play a vital role in machinery, it is important to regularly inspect bearings for problems, while ensuring that maintenance is performed on time. This article details the causes of bearing noise and what to do about it.

1. The reason for the noise of the bearing

If the bearing suddenly starts to make noise during operation, there is a problem with the bearing. When a bearing’s raceway is damaged, excessive noise is heard, causing the rolling elements to bounce or rattle during rotation.

There are many causes of bearing noise, but the most common is contamination. It could be that contamination occurred during bearing installation, and particles that remained on the raceways caused damage when the bearing was first run.

Guards and seals can be damaged during bearing lubrication, rendering them ineffective against ingress of contaminants, a particular problem in highly polluted environments.

Contamination is also common during lubrication. During the relubrication process, foreign matter may stick to the end of the grease gun and enter the machine.

These foreign objects can cause them to enter the raceway of the bearing. When the bearing starts to run, the particles will start to damage the bearing’s raceways, causing the rolling elements to bounce or rattle and create the noise you hear.

2. What should I do after the bearing makes noise?

The noise from the bearings can sound like whistling, rattling or growling. Unfortunately, when you hear this sound, your bearing has failed and the only solution is to replace the bearing as soon as possible.

You may find that adding grease to the bearings can reduce noise. That means the problem has been solved, right?

Unfortunately, this is not the case. Once the bearing starts to make noise, adding grease will only mask the problem. It’s like putting a plaster on a stab wound – it needs urgent attention and the sound just comes back.

You can use condition monitoring techniques such as vibration analysis or thermal imaging to predict when a bearing is likely to fail catastrophically and calculate the latest time when a bearing can be safely replaced.

3. How to prevent bearing failure?

It can be tempting to just replace the faulty bearing and continue with day-to-day business operations. However, it is important not only to replace the bearing, but also to find the root cause of the failure. Conducting a root cause analysis will identify the underlying problem, enabling you to take mitigation actions to prevent the same problem from recurring.

Be sure to use the most effective sealing solution for your working conditions, and check the condition of the seal every time you perform maintenance, helping to keep contaminants out.

It is also important to ensure that the correct assembly tool is used for the bearing. This will help prevent damage during installation.

4. Bearing monitoring

Continuous bearing monitoring gives you the best opportunity to quickly identify and resolve potential bearing problems. A condition monitoring system is a great way to keep a machine’s health under constant check.

At ACORN, we offer SKF condition monitoring equipment ranging from stroboscopes and vibration sensors to full condition monitoring systems that can be seamlessly integrated with your machinery for remote monitoring.


If your bearing suddenly becomes noisy during operation, it has failed. It may still work now, but it will be getting closer and closer to catastrophic failure. The most common cause of noisy bearings is contamination, which can damage the bearing’s raceways, causing the rolling elements to bounce or rattle.

In conclusion, the only solution after the bearing is making noise is to replace the bearing, applying grease will only mask the problem.