Reference
Failure-mode taxonomy
Two standards, one per part family. Codes are the standard's own clause numbering where it exists, so every finding traces back to the document. Severity is a five-step operational ramp; attribution is the root cause, kept separate from the mode on purpose.
ISO 15243, rolling bearings
| Code | Failure mode | Worst-case severity |
|---|---|---|
| 5.1 | Fatigue (rolling contact) | ◕ 3 Remove from service |
| 5.2 | Wear (abrasive / adhesive) | ◑ 2 Plan repair |
| 5.3 | Corrosion (moisture / fretting) | ◕ 3 Remove from service |
| 5.4 | Electrical erosion | ◕ 3 Remove from service |
| 5.5 | Plastic deformation (indentation) | ◑ 2 Plan repair |
| 5.6 | Fracture and cracking | ● 4 Safety-critical |
ISO 10825, gear teeth
| Code | Failure mode | Worst-case severity |
|---|---|---|
| wear | Wear | ◑ 2 Plan repair |
| scuff | Scuffing | ◕ 3 Remove from service |
| plastic | Plastic deformation | ◑ 2 Plan repair |
| cfatigue | Contact fatigue (pitting / spalling) | ◕ 3 Remove from service |
| crack | Cracks | ● 4 Safety-critical |
| fracture | Tooth fracture | ● 4 Safety-critical |
| corrosion | Corrosion | ◕ 3 Remove from service |
Severity ramp
○ 0
Serviceable
Return to service
◔ 1
Monitor
Re-inspect at next interval
◑ 2
Plan repair
Schedule rework
◕ 3
Remove from service
Pull the part
● 4
Safety-critical
Quarantine batch, escalate
Attribution, the third axis
A mode says what the surface shows; attribution says why it got there. The same pit is a different problem if it came from contamination rather than end-of-life fatigue, and the batch-level action differs.
Operating duty
Service fatigue at or near rated life: expected wear-out, not a fault.
Lubrication
Starvation, the wrong grade, or a film that has broken down.
Contamination
Solid particles or moisture carried into the contact.
Mounting / alignment
Misalignment, bad fit, or damage taken during fitting.
Overload
Load or preload past design: shock, overspeed, or static brinelling.
Electrical
Stray current passage across the contact.
Corrosion
Corrosive environment, standing moisture, or fretting.
Handling
Transport, storage, or install damage before the part ever ran.
Plausible cause per mode
Which causes ISO ties to each damage class. Not a gate, an inspector can attribute anything, but a finding whose cause is off this list is flagged for a second look.
5.1 Fatigue (rolling contact)Operating duty · Overload · Contamination · Mounting / alignment
5.2 Wear (abrasive / adhesive)Lubrication · Contamination
5.3 Corrosion (moisture / fretting)Corrosion · Handling · Lubrication
5.4 Electrical erosionElectrical
5.5 Plastic deformation (indentation)Overload · Handling · Contamination
5.6 Fracture and crackingOverload · Mounting / alignment · Handling
wear WearLubrication · Contamination
scuff ScuffingLubrication · Overload
plastic Plastic deformationOverload
cfatigue Contact fatigue (pitting / spalling)Operating duty · Overload · Lubrication
crack CracksOverload · Mounting / alignment
fracture Tooth fractureOverload · Mounting / alignment
corrosion CorrosionCorrosion · Handling
SHEET
TAX-01
ISO failure-mode catalogue
REV C
SCALE NTS