Material Drying
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PVDF Extrusion Bubbles and Moisture Control
Problem Phenomenon
【Problem phenomenon】Internal bubbles and surface pinholes in PVDF extruded pipe, failing the pressure test
Cause Analysis
Residual moisture in the raw material, volatiles in the resin, and air intake of the extruder jointly form bubbles; the LG Chem troubleshooting manual requires sufficient drying, use of the vent port, and ensuring emptying of residual material at shutdown
Solution
Dry to below 0.05% moisture content and protect against moisture during storage and transport; open the vacuum vent port of the extruder; thoroughly empty at shutdown to prevent residual material degradation and gas generation; check air intake points in the feed zone
Key Takeaway
For extrusion bubbles, first check drying and the vent port; empty at shutdown to prevent residual material gas generation; After confirming effectiveness, fix 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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