Molds & Tooling
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PPO Cold Slug Marks
Problem Phenomenon
Cold slug marks and uneven gloss appear on the surface of PPO products, mostly near the gate, and are especially severe in the early mold shots of production.
Cause Analysis
Cold slugs from the nozzle or runner enter the cavity and form spots; low mold temperature causes rapid cooling of the melt front; insufficient cold slug well design cannot trap cold slugs; mold temperature is not stable at startup.
Solution
①Enlarge the cold slug well volume and optimize its position; ②appropriately increase nozzle temperature to prevent cold slugs; ③fully preheat the mold at startup; ④inspect the nozzle heating system.; After adjustment, continuously sample to verify the effect, and resume mass production after confirming stability
Key Takeaway
PPO cold slug mark prevention relies on cold slug wells and temperature management; early mold shots at startup need strengthened inspection; nozzle temperature control is a detail but critical.; After confirming effectiveness, fix the parameters and practices into the work instruction to prevent recurrence
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