← Defect Guide
Tiger Stripe
Alternating glossy/matte bands perpendicular to flow, mostly in PP/TPO. Notably, raising injection speed makes it worse.
◆ Common Causes
- •PP wall slip and flow instability
- •Mold or melt temperature too low
- •Injection speed too high (worsens banding)
- •Long flow length (e.g., bumpers)
- •Low-flow (low-MI) material limitation
◆ Solutions
- ✓Raise mold and melt temperature (single biggest lever)
- ✓Lower injection speed; use a constant-speed profile (★ do NOT raise speed)
- ✓Consider high-flow (high-MI) or nucleated grades
- ✓Review gate location and flow length
- ✓Recognize material-driven limits
◆ Resin-Specific Notes
PP
The classic tiger-stripe resin. Higher mold temp and slower speed are key.
PP/EPDM
Common in bumpers/trim. Review flow length and grade.
TPO
Soft PP-family. Same approach.
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This content is a field-reference summary. Final judgment requires on-site engineer verification.