← Defect Guide
Burn Mark
Charring or discoloration from compressed-air combustion (diesel effect) or thermal degradation.
◆ Common Causes
- •Injection speed too high (compressed-air combustion)
- •Poor venting
- •Melt temperature too high (thermal degradation)
- •Excessive residence time
- •Hot runner temperature too high
◆ Solutions
- ✓Reduce injection speed
- ✓Add, enlarge, or clean vents
- ✓Lower melt temperature
- ✓Shorten cycle time
- ✓Purge screw
◆ Resin-Specific Notes
POM
Generates formaldehyde gas. Venting is essential. Minimize residence time.
PVC
Generates HCl gas. Temperature control is critical.
PA
Moisture can generate gas. Drying is important.
ABS
Degradation begins above 260°C.
◆ Resins Prone to This Defect
Keep using it on the floor — your diagnosis history and machine conditions accumulate in the app.
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This content is a field-reference summary. Final judgment requires on-site engineer verification.