Bearing misalignment is one of the major causes of bearing failure in industrial equipment, such as pumps and motors. The misalignment can cause cage fracture that ultimately damages the bearing, resulting in machine failure and costly downtime. This is why you should put emphasis on identifying bearing misalignments, their causes and try as much as possible to avoid them.

Causes of Bearing Misalignments

There are three common types of bearing misalignments, radial, angular, and parallel misalignments, and they can be caused by a number of issues:

• Poor mounting: If the bearing is not mounted correctly, it can result in radial or angular misalignments. For example, if the shaft being fitted with bearings expands significantly or is oversized, it can compromise their alignment and result in early failure.
• Fatigue: Fatigue, also known as spalling, is the fracture of the running surfaces, which ultimately results in the removal of small particles. The new uneven surfaces become the sources of major misalignments.
• Inadequate internal clearance: The internal clearance of a bearing greatly impacts the load size, friction, and fatigue levels of a bearing. If this clearance is not adequate, it can cause heat build-up, lubrication issues, amplified friction, and finally, misalignment. It might even cause the bearing to lock up completely.

Solutions for Bearing Misalignment

To address the problem of bearing misalignment, the first step is to understand what causes them. This is crucial because you will be able to take caution even before installing the bearings on the shaft of the motor, pump, or other equipment. Here are some solutions to bearing misalignment that you should consider:

• Diagnose the Misalignment

You cannot be able to address bearing misalignment before identifying the type. Therefore, start by running complete bearing diagnostics, which should include a review of the rolling element path. When bearings rotate, they create a wear path and outer raceway. If a bearing is properly aligned, a running path down the center of the rings (both inner and outer) will be visible. However, a misaligned bearing will show uneven paths as shown below:

Once you notice the bearings have some misalignments, ensure it is diagnosed correctly to determine the extent. If the damage is extensive, it might be a good idea to have the bearing replaced before it can cause damage to other parts of the system.

• Avoid Misalignment Completely

This is perhaps the most effective method of addressing bearing misalignment. If you are extra careful during bearing installation, it might be possible to avoid the problem. You can do this by ensuring that the mating housing and shaft components are designed properly. For example, the housing should be rigid enough to offer support bearing.

In the event that two bearings are to be mounted in the same housing, the housing bore surfaces should be prepared to ensure both bearings can be installed in one operation. When installing the bearings, you should also follow these tips to avoid misalignment:

1. The fillets of the shaft and housing should not contact the chamfer of the bearing.
2. All mating surfaces should be cleaned when installing bearings.
3. Shaft and shoulder abutting surface edges should not have blurs.

• Consider Using Self-Aligning Ball Bearings

Another solution that you should consider is shifting to self-aligning ball bearings. These bearings come with a spherical raceway that features a center curvature coinciding with the bearing. This implies that the axis of the inner ring, cage, and balls deflect around the center. The only issue with self-aligning bearings is that they tend to create a small contact angle between the raceway and ball, which can result in lower loading capacity compared to similar deep-groove ball bearings.

Bearing misalignment means trouble, especially when not detected early. This is why you should inspect the bearings regularly and ensure all machines are maintained in good condition for top performance. Remember that even when the bearing is running with no misalignment, it should be inspected regularly and replaced in line with the manufacturer's recommendations.