Unexpected causes of bearing failure

When bearings are maintained, they allow the machinery to run with very few problems, but when they fail, the motor fails too.

By David Manney, L&S Electric Inc. September 11, 2017

There are many moving parts to any piece of equipment. One moving part requiring particular attention are the bearings. When maintained and operating well, they allow the machinery to run with very few problems. When the bearings fail, though, the motor fails along with it.

Most of us are familiar with the common reasons for bearing failure. They include:

  • Bearing misalignments

  • Improper mounting

  • Contaminated or improper lubrication

  • High temperatures

  • Bearing fatigue

  • Improper storage techniques.

These are on average the first things to look for when problems occur with bearings. There are also other issues that arise and result in premature bearing failure. Here are three that may not be on the usual radar.

Damage to the bearing cage

Many different issues occur with the bearing cage, resulting in a shortened bearing life. Included among these matters is cage pillar fractures and guide or pocket wear.

Damage occurs to the bearing cage for different reasons, many associated with the handling and mounting of the bearings. Issues also occur due to vibration, inadequate lubrication, high temperatures, and large loads. To avoid a problem with the bearing cage, reduce vibration and mount the bearings as instructed. You should also lubricate the bearings to reduce temperature and friction; again following manufacturers instructions.

Bearing seizure

Seizure of the bearings occurs when excessive heat exists during rotation. As a result of the excessive heat, many of the elements associated with the bearings begin to soften and melt, including the rolling elements, raceway rings, and the cage. These issues lead to bearing seizure and the possibility of damage to the equipment where they are used.

Some of the issues that lead to bearing seizure include:

  • Improper lubrication techniques

  • Lubrication contamination

  • Excessive rotational speed

  • Load and shaft misalignments.

It is possible to avoid many of these problems using proper lubrication and sealing the bearings. These two tasks reduce excessive loads. Making regular examinations of shaft alignment becomes part of an effective maintenance program.


Another issue that occurs with bearings is fretting. Fretting takes place between the rolling elements and the raceway ring. It often shows up as black or brown particles.

Like many issues associated with the bearings, fretting result because the bearings are not lubricated following a set schedule. Fretting also occurs with certain types of vibration.

The bearings often tell a tale when equipment failure takes place. Take the time to examine the bearings inside and out. Learn from any mistakes.

Above all, apply the principles of a preventive maintenance program at your facility to ensure that problems are few and far between.

Three types of bearing maintenance strategies

Periodic maintenance, predictive maintenance, breakdown maintenance can help with bearing maintenance strategies.

Periodic maintenance

Over time, your applications and equipment will begin to wear down and fail. In fact, a study found that 45% of unscheduled downtime is a direct result of aging equipment.

Periodic preventive maintenance sets up a regular schedule for you to clean, inspect, and fix up your applications and parts to maintain the health of your equipment. A well-planned maintenance schedule can save your business a lot of money and allow you to have more control over downtime instead of waiting for an issue.

Predictive maintenance

The following are potential warning signs for aging or failing applications:

  • Excessive vibration

  • Overheating

  • Steam, air, or gas leaks

  • Contamination

  • Electrical imbalances

  • Misalignment.

These check-ins can be performed through manual inspection or through monitoring technology. If no signs are spotted, it means that you should be set until the next inspection.

Run-to-fail/breakdown maintenance

This type of maintenance isn’t so much a strategy as much as the choice not to conduct any maintenance work until something stops working. While this usually isn’t the most cost-effective solution for businesses that can’t afford unexpected downtime, there are some situations where it can be an advantageous approach.

One such example is if equipment failure won’t affect production and can be quickly and easily repaired. However, this approach likely is a bad choice for parts like bearings.

Consider this simple piece of advice: doing things right the first time saves you problems down the road.

One way to limit to the amount of time and resources spent on maintenance is to invest in quality bearings. Good bearings can keep your application running smoothly while lasting longer than poorly-made or ill-fitting parts.

Bearing failure accounts for over 50% of all electric motor breakdowns. Recognizing how those problems occur and knowing how to prevent them allows your equipment to run smoothly over time.

David Manney is marketing administrator at L&S Electric. This article originally appeared on L&S Electric’s online blog. L&S Electric is a CFE Media content partner.

Original content can be found at lselectric.com.