Material Drying
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HDPE film bubbles and pinholes
Problem Phenomenon
Tiny bubbles and pinholes appear in the film, becoming defect points during lamination or printing.
Cause Analysis
The moisture content of the raw material exceeds the standard and is not fully dried, and the moisture vaporizes in the melt; leakage of cooling water in the barrel or hopper also introduces moisture.; when troubleshooting on site, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Pre-dry the raw material to control the moisture content within 0.3%; ②repair the barrel and hopper cooling system to prevent leakage; ③check the moisture content of the recycled material; ④store the raw material sealed.
Key Takeaway
Film bubbles mostly originate from moisture; check both drying and leakage prevention, and moisture content testing is a quick criterion.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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