Bearings are a frequent component in engineering systems that you will encounter throughout your career. Bearings are critical to the operation of many devices and procedures, and their failure may be disastrous. Bearings fail for various causes, and we will discuss the top seven below.
1. Lubrication Failure
Surprisingly, lubrication failure accounts for around 80% of all bearing failures. This includes utilizing the wrong lubricant, not enough lubrication and overheating, which causes lubrication deterioration. Lubricants primarily reduce friction and wear while also transporting away heat generated by the bearing.
Grease and oil are the two lubricants used in bearings. Grease is quite similar to oil, except it contains a thickening. Furthermore, the key method to discern the difference at room temperature is grease is solid, whereas oil is liquid. Size, speed of operation, viscosity, and bearing type are all considerations in determining how much lubrication to apply to a bearing.
When checking a bearing, discolored lubrication indicates that the bearing has become overheated. Excessive heating will also cause ‘bluing’ on the bearing.
2. Contamination
Contamination occurs when foreign particles, such as dirt, penetrate the bearing lubricant and become trapped inside the bearing system. Because of three-body abrasive wear, hard particles will cause plastic deformation on the bearing raceways. This wear will produce noticeable scratches, gouges, and plowing marks.
Contamination is relatively easy to arise. Hence surrounding areas must be cleansed, and bearings must be handled with care. This greatly reduces the possibility of contamination. Contamination might come from solid particles left in the bearing after production.
3. Fatigue
Spalling is the failure mode caused by bearing fatigue. Spalling occurs due to surface or subsurface fatigue, which results in cracking in the raceways. Flakes develop, and the material breaks away due to the repetitive action of the rolling components passing over these fissures. When spalling begins, the deterioration progresses swiftly, and the bearing becomes unusable.
4. Improper Mounting
A press or shrink fit is the most frequent method of fitting bearings. If the fit between the shaft and the inner race is excessively tight, the inner race will expand, causing extra stress and removing any needed clearance. The outside race in housing is also related to fit difficulties. A too-tight fit may cause the outer ring to compress excessively, removing any essential clearance. When installing bearings, they must be forced against a neighboring component to assist in introducing the right bearing pre-load.
Furthermore, the poor installation might cause damage to the bearing during the fitting procedure.
5. Excessive Loading
Excessive loading will shorten the life of a bearing due to premature failure. Excessive loads on bearings will cause spalling to occur sooner and may cause the bearing to overheat. Both of these factors can lead to the failure of a bearing.
6. Overheating
Overheating is caused by high operating temperatures, which are generally caused by insufficient lubrication. This applies to both too much and needing to be more. If too much oil is in a bearing, the bearing components will begin churning the grease, using a lot of energy to move the grease and raise the temperature. If there is insufficient lubrication, metal-on-metal contact may occur, resulting in local hot spots. Still, the lubricant will not be able to remove excess heat owing to the tiny amount.
7. Misalignment
Non-contact seals might rub if the shaft is misaligned concerning the bearing housing. The friction will cause excessive heating and increased noise levels during operation. Furthermore, the seal’s integrity will be jeopardized due to rapid wear.
If two housings or shafts are not lined up in a straight line, extra stress on the bearing might occur, resulting in premature failure.
Summary
Non-contact seals might rub if the shaft is misaligned with the bearing housing. The friction will cause excessive heating and increased noise levels during operation. Furthermore, the seal’s integrity will be jeopardized due to rapid wear.
If two housings or shafts are not lined up in a straight line, extra stress on the bearing might occur, resulting in premature failure.
