Injection Molding
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Burning from poor venting in PET preform '2079851475616104452
Problem Phenomenon
Burn marks or black spots appear at the PET preform end (far from the gate), accompanied by irritating odor.
Cause Analysis
Poor cavity venting; air rapidly compressed producing high temperature (diesel effect) causing local burning, vent grooves blocked or injection too fast.
Solution
Deepen and widen vent grooves (0.02-0.04mm); clean accumulated material; appropriately reduce injection speed; optimize gate position.
Key Takeaway
PET preform burning is the result of air not being able to escape in time; improving venting is fundamental.
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