Ball bearing failure occurs due to a wide range of causes and scenarios. Below are among the types of failure in ball bearing, as well as key information on each.
This issue is referred to as the splitting off of some pieces of the ball bearing material from the raceway’s smooth surface. Flaking commonly occurs because of rolling fatigue. Hence, the different regions of the bearing tend to have coarse and rougher texture over time.
There are several factors that contribute to flaking concerns with ball bearing. These issues include contamination with foreign debris, moisture, misalignment or poor mounting, incorrect lubricant, brinelling, smearing and corrosion pits. Unevenness in the rigidity of the housing, as well as improper precision for the housing or shaft, are other aspects that contribute to this problem.
Bearings may also feature a pitted surface that comes with a dull quality or roughness. Pitting is commonly found in the raceway or rolling element surface. Poor lubrication and moisture or humidity present in the workplace can both lead to this problem. The same holds true once debris gets caught and mixed in the lubricant.
To address these concerns, it is important to use the right lubricant and be sure to filter well the lubrication oil. You should also check and ensure the quality of the sealing mechanism. By doing so, you can prevent dust and contamination that are some causes of this problem.
- Improper Fitting
Tight fits can cause a worn path at the bottom portion of the raceway, which can extend to the outer and inner rings’ entire circumference. Once there is an excess of the interference fits on the radial clearance at the optimal temperature for operating motors, overloading of the ball bearings arise. Several problems will occur such as high torque that goes with a rapid increase in temperature.
As you continue to operate the motor with this condition, premature wear, and tear, as well as serious damages can result. To address this issue, it is best to perform a corrective action such as a reduction in the total interference.
- Poor Alignment
You will notice this type of failure once the ball wear path appears to be no longer parallel to the edges of the raceway. Usually, a rise in abnormal temperature occurs along with misalignment that is more than 0.001 inch. Moreover, the cage ball-pockets may also depict a heavy wear.
A way to solve these issues is by performing some corrective actions including inspection of the housing and shafts, which can help you identify any existing runout of bearing seats. You can also use high-quality locknuts and single point turned threads on shafts that are not hardened. On the other hand, hardened shafts will require ground threads.
- Lubricant Failure
In the case of lubricant failure in ball bearing, you will notice a bluish or brownish ball track because of this concern. With a combination of excessive wear and tear of balls, cages and rings will soon become less efficient. Overheating will also arise, which is followed by serious damages and failure.
Ball bearings need proper lubrication between the races and balls, as well as between the balls, rings, and cage. As the problem persists, excessive production of heat can become an additional concern. Furthermore, it is important to note that the lubricant’s properties are damaged because of excessive temperature and restricted flow of lubricant.
Several signs of corrosion in ball bearings include red or brown-colored areas on the cages, ball bearing bands, balls and raceway. These are all problems that are caused by corrosive fluids and elements that get into bearings. Additionally, corrosion can be a cause of fatigue and failures in motors, which are worst situations that arise from this problem.
There are some techniques that can prevent this issue. For instance, you may use bearings that are integrally sealed to prevent corrosion. Another way is by diverting any corrosive fluids to keep these away from areas surrounding the bearing.
- Excessive Loads
Premature wear and fatigue are commonly linked with excessive loads on a ball bearing. Other issues that cause early failure due to fatigue are brinelling, poor pre-loading and tight fits. Over time, serious damages can result, which will require unplanned downtime because of repairs or replacement.
To prevent this concern, you can consider reducing the load. You may also want to use a bearing the has a greater capacity for heavy loads for better support.
Once loads go beyond the ring material’s elastic limit, brinelling occurs. Indentations found in the raceways are signs of brinelling. These marks also cause an increase in the bearing vibration. Other issues that cause this type of failure include severe impact and static overload.
The best way to solve this problem is by isolating the bearings from the external vibration. You can do so by using greases that have anti-wear components in them.
- Reverse Loading
An angular type of contact bearing is intended to accept axial loads in a single direction. Once loading is done in an opposite direction, a truncation of the elliptical contact area found on the outer ring occurs. This is caused by the low shoulder found on one side of the external ring. Thus, excessive stress can arise, and this is followed by greater vibration, excessive heat, and premature failure.
- Loose Fits
Aside from tight fits, loose fits can result in failure in ball bearings. Fretting can also arise once there is a slight, yet continuous relative motion that occurs between the mating parts. Basically, fretting is the production of fine metal particles, and these oxidize and leave a brown color on the surface. This is an abrasive type of material that further increases the looseness of the fit.
Also known as fatigue failure, this is a fracture of the bearing’s running surfaces. It can occur in the balls, outer or inner rings. Since this is a progressive failure type, it can spread and worsen because of further operation with this condition. An increase in vibration will result from this problem, and it is advisable to replace the bearing to improve life span.