Electric motors are vital to any manufacturing facility. They represent a significant amount of commitment in investment and maintenance. Protecting your investment requires paying attention to details. Healthy ball bearings are one of the most important details keeping your investment from failure.
With proper maintenance and care, ball bearings last for a long time. Because of their fragility, it is important to ensure correct installation and application of the bearings to extend their lifespan. Certain issues occur, however, if bearings are not lubricated or installed the correct way, aside from operating in a contaminated work environment.
Here, we look into five common bearing problems and how to address them.
False brinelling refers to the condition where elliptical wear marks form in an axial direction at the different positions of the ball bearing. It is also common to find a sharp demarcation along with a bright finish often surrounded by brown debris forming a ring. The usual culprit for this type of failure is external vibration. Vibration impacts the motion between the raceway and balls in non-rotating bearings.
In case the bearing is not turning, it is impossible to form an oil film preventing the wear of the raceway. As a result, the wear debris tends to oxidize, and this speeds up the wear process.
One effective technique to address this issue is to isolate the bearings from the source of external vibration. One way to isolate the bearings is to use grease containing molybdenum disulfide. These components prevent wear when applied to the bearings when they oscillate (just like in an actuator motor).
True brinelling also occurs, and this happens when there is an excessive load that goes beyond the ring material’s elastic limit. Using hammers during bearing installation and removal, or forcing a bearing onto a shaft can cause brinelling.
When you see indentations in the raceways, these suggest failure. The problem gets worse with greater bearing vibration and premature fatigue, as well as failure. This is why it is important to avoid pushing the outer ring just to secure the inner ring onto the shaft. Never use too much force when installing bearings.
Premature fatigue and failure in bearings occur due to excessive loads, along with improper preloading and tight fits. At first, the issue appears as a normal fatigue, except for the presence of overheating and spalling in the affected area.
Minimizing the load addresses this problem. Redesigning the unit is another possible solution by using a bearing that handles a greater load or weight capacity.
In a typical situation, angular contact bearings receive an axial load in a single direction. When loading these components in another direction, this leads to the most stress on the bearings. This stress creates friction and increasing temperatures, which increases vibration and leads to premature failure.
Correct installation of the bearing is an effective course of action to take when reverse loading happens. It is also essential that when you install the angular contact bearing, you need to put the resultant thrust (with the marking “thrust”) on the wide face of the outer ring, which is the inner ring’s opposite face.
Fatigue Failure or Spalling
Spalling is a type of problem with bearings is typical with the balls, outer, or inner ring. It appears as a fracture or damages of the running surfaces. This leads to the removal of small particles of the material affected. When ignored, the continued operation of the damaged components increases spalling.
Immediately replace the part if fatigue failure affects the bearing. Another practical solution is redesigning the system using a more robust bearing with greater resistance to fatigue failure.
Contamination is a common reason for bearing failure. The typical signs of contamination include dents in the balls and raceways that lead to wear and excessive vibration. There are also several types of airborne contaminants; including dirt and dust that get into the tight spaces of the bearing. Dirty work areas and foreign elements mixed in the lubricants increase the risk of contamination.
To cut the instances of contamination failures, ensure that all work areas, fixtures, and tools are clean. If there are grinding operations taking place nearby, move all bearing assembly sites farther away. Be sure to keep seals in check since any damaged ones no longer serve their purpose of protecting the bearings from contamination.
Becoming being aware of these issues and the corresponding solutions prolongs the lifespan and condition of the bearings. Healthy bearings enhance productivity and reduce the chances of unplanned downtime.