Failure analysis
Abnormal operation lookup: high temperature, noise, vibration and torque
Quick answer
Four symptoms you can notice before you remove the bearing, each with its usual causes and the first action to take.
How to read the tables
These tables list what to suspect when a running bearing shows one of four symptoms. Start with the symptom, check the likely causes in order, and take the matching action. Where the table says replace the bearing, inspect the cause first or the new bearing will fail the same way.
Rising temperature
| Likely cause | What to do |
|---|---|
| Internal clearance too tight | Replace the bearing, correct the clearance and fit |
| Ring creeping on shaft or in housing | Replace the bearing, correct the interference |
| Heavier load than designed | Refit, correct the load by adjusting the housing |
| Poor alignment when mounted | Refit and re-centre, or widen the clearance |
| Defect in the bearing | Replace; find the cause after inspection |
| Wrong amount of lubricant | Correct the amount (too much or too little) |
| Wrong lubricant | Change to the right lubricant |
| Wrong lubrication method | Correct the method by refitting or replacing parts |
| Oil seal too tight, short of lubricant or the wrong seal | Correct the interference, supply lubricant, fit the right seal type |
| Labyrinth seal or another part rubbing | Refit or modify the parts |
Excessive or odd noise
| Noise pattern | Likely cause | What to do |
|---|---|---|
| Regular, at uniform intervals | Scratches or dents on a raceway | Repair or replace; handle bearings carefully |
| Regular, at uniform intervals | Electric pitting or fluting | Replace, and stop current passing through the bearing by changing the design or grounding |
| Regular, at uniform intervals | Crack in a ring | Replace the bearing |
| Regular, at uniform intervals | Flaking on a raceway | Replace the bearing |
| Regular, at uniform intervals | Raceway roughened by foreign matter | Repair or replace, and clean the lubricant system |
| High-pitched metallic | Internal clearance too narrow | Replace or open the clearance |
| High-pitched metallic | Lubricant shortage | Supply lubricant |
| High-pitched metallic | Rolling elements sliding | Change to the right lubricant or reduce the running clearance |
| Irregular, at uneven intervals | Foreign matter in the bearing | Change to the right lubricant and clean |
| Irregular, at uneven intervals | Contact with a neighbouring part | Refit or modify the parts |
| Irregular, at uneven intervals | Flaw or flaking on a rolling element | Replace the bearing |
| Irregular, at uneven intervals | Worn cage | Replace the bearing |
High vibration
| Likely cause | What to do |
|---|---|
| Foreign matter in the bearing | Change to the right lubricant and clean |
| Clearance too wide | Refit the bearing or replace it |
| Flaw on a raceway or rolling surface | Replace the bearing |
High turning torque
| Likely cause | What to do |
|---|---|
| Poor mounting | Refit, widen the clearance and take care with alignment |
| Seal rubbing too hard | Refit and reduce the seal interference |
| Wrong lubricant or too much of it | Reduce the amount, and do not over-fill |
Takeaway. Match the symptom first. Noise that repeats at an even pace points to a defect on a raceway or ring; irregular noise points to dirt, a rubbing part or a worn cage.
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