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During kiln startup, a customer reported that four out of five SSiC rollers experienced end-face chipping.
Surprisingly, one roller remained completely intact.
The temperature was increased from room temperature to approximately 946°C over a 12-hour period.
The customer initially suspected:
- Thermal shock
- Material inconsistency
- Manufacturing defects
However, inspection results did not support these conclusions.
The damage was concentrated at the roller ends.
No significant center cracking was observed.
The surviving roller was located in a slightly different support position.
This observation suggested a support-related effect rather than a material issue.
During heating:
- Thermal expansion occurred
- Contact conditions changed
- Local stresses increased
The support interface created localized contact loading.
As temperature increased, these stresses became concentrated near the roller ends.
The result was:
- Edge chipping
- Local micro-fracture
- Surface damage
The surviving roller experienced slightly different contact conditions.
This reduced local stress concentration and prevented crack initiation.
The incident was primarily caused by contact stress and support interaction rather than classic thermal shock failure.
Related Reading:
Why Thermal Shock Is Often Misdiagnosed in SiC Component Failure?
Why Most Roller Cracks Start from Contact Zones
Why Contact Stress Is More Dangerous Than Bending Stress?