Bearing failure modes: causes, identification and fixes
23 damage and failure patterns, grouped the way ISO 15243 groups them. Each guide covers what it looks like, how it develops, the typical causes, how to confirm it and what to change so it does not come back.
Rolling contact fatigue
The steel simply wore out from repeated stress, or was pushed there early by poor lubrication.
| Failure mode | In short |
|---|---|
| Subsurface-initiated fatigue | The raceway fails from the inside out. |
| Surface-initiated fatigue (surface distress) | The oil film was too thin and the surface peaks started to touch. |
Wear
Material rubbed away: by grit, or by surfaces dragging instead of rolling.
| Failure mode | In short |
|---|---|
| Abrasive wear | Grit in the lubricant is sanding the bearing down. |
| Adhesive wear (smearing & skidding) | Metal dragged across metal: surfaces tear and weld on a tiny scale. |
Corrosion
Chemical attack from water, or micro-movement that keeps stripping the protective oxide.
| Failure mode | In short |
|---|---|
| Moisture corrosion | Water got in, and rust, etching or frosting followed. |
| Fretting corrosion | Tiny movements between ring and seat grind off rust-coloured powder. |
| False brinelling | Damage from standing still while vibrating. |
Electrical erosion
Current passing through the bearing, arcing across the oil film and cratering the steel.
| Failure mode | In short |
|---|---|
| Excessive current erosion | A tiny arc-weld at every contact. |
| Current leakage erosion (fluting) | A low, steady current draws washboard ridges across the track. |
Plastic deformation
Permanent dents from overload, impact, rough mounting or trapped debris.
| Failure mode | In short |
|---|---|
| Overload deformation (true brinelling) | Rolling elements pressed permanent dents into the raceway. |
| Indentations from particles | Over-rolled debris leaves a scatter of dents. |
| Handling and installation damage | Nicks, gouges and dents put there before the bearing ever ran. |
Cracking & fracture
The steel could not carry the stress: broken in one event, or cracked progressively.
| Failure mode | In short |
|---|---|
| Forced fracture | Stress exceeded strength: the ring or cage simply broke. |
| Fatigue fracture | A crack grew a little with every revolution until the ring let go. |
| Thermal cracking | Friction heat on a sliding surface cracked the steel. |
| White etching cracks (brittle flaking and axial cracks) | Early cracks in the steel that standard life calculations do not predict. |
Related conditions
Not separate ISO modes, but the overheating, seizure, cage and alignment problems that surround them.
| Failure mode | In short |
|---|---|
| Overheating & lubricant breakdown | Colour is a temperature record. |
| Seizure (end-stage failure) | What is left when overheating is ignored. |
| Cage damage | The part that gets looked at last. |
| Misalignment & distorted seats (edge loading) | The load path is in the wrong place. |
| Excessive endplay and loose setting (scalloping) | Too much play lets the rollers fall out of step with the load. |
| Ring creep and loose fits | A ring turning on its seat grinds both away until something gives. |
| Lubricant failure (starved, over-filled, mixed or worn-out) | The oil film is gone, and the metal has noticed. |