Injection Molding
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PET Injection Preform Black Specks
Problem Phenomenon
Black small dots appear on the preform, more obvious after bottle blowing.
Cause Analysis
Carbonized material at dead corners of the barrel/hot runner falls off; PET is sensitive to heat history, and regrind or contamination also introduces black specks.
Solution
①Clean the hot runner and barrel dead corners; ②avoid long-time heat preservation; ③control regrind cleanliness; ④thoroughly purge when changing material.
Key Takeaway
Preform black specks = dead-corner carbonization.
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