9 min read · 7 May 2026 · SLS Engineering Team
Reading Bearing Failure Modes — A Visual Cheat-Sheet
Eight failure patterns and what each one tells you about the root cause.
When a bearing comes off the shaft, the damage pattern is the diagnostic. Match what you see to the cause before re-ordering — otherwise the next bearing fails the same way.
1. Spalling on the loaded zone
Fatigue spalling spread along the loaded raceway is end of L10 life — the bearing simply ran its hours. Replace and recalculate dynamic load rating if the application has changed.
2. Spalling on the unloaded side
Causes: excessive interference fit or wrong clearance class. Re-check shaft tolerance; consider C3 internal clearance.
3. Fluting / washboard marks
Classic electrical erosion signature, especially in VFD-driven motors. Solution: insulated bearing (e.g. /VL0241), ceramic balls, or a shaft grounding ring.
4. Brinelling (evenly-spaced dents)
Static shock load (drop during install) or transport vibration through a stationary bearing. Use false-brinelling-resistant grease for stored machines.
5. Frosting and micro-pitting
Lubricant film breakdown at the rolling contact. Check viscosity at operating temperature and consider an EP additive.
6. Discolouration (straw → blue → black)
Temperature run-away. Likely over-greasing, restricted oil flow, or wrong preload.
7. Cage wear and breakage
Vibration, misalignment, or skidding under light load. Add a minimum preload spring on lightly-loaded angular contact arrangements.
8. Smearing in the no-load zone
Usually starvation of lubricant during start-up.
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