Injection Molding
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HDPE Burnt and Trapped Gas
Problem Phenomenon
Product ends and rib positions are burnt black, and carbon deposits appear at corresponding mold positions
Cause Analysis
When HDPE fills at high speed, cavity air is compressed and heated, forming trapped gas burning; poor venting and excessive injection speed are the main causes; ends of deep cavity rib positions are high-incidence areas; during on-site troubleshooting, verify item by item according to this mechanism to avoid blindly adjusting the machine based solely on experience
Solution
①Add vent grooves at ends and rib positions; ②reduce end-stage injection speed; ③regularly clean carbon deposits in vent grooves; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
HDPE burnt treatment prioritizes venting; speed segment control is a supporting measure; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence; include this case in the defect archive as a reference for troubleshooting similar problems in the future
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