Extrusion & Post
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HDPE film gel particles and fisheyes
Problem Phenomenon
Transparent small particles and fisheye-shaped defects appear on the surface of the blown film, affecting appearance and heat-sealing quality.
Cause Analysis
Unplasticized particles, degraded gel or impurities in the raw material enter the film with the melt; insufficient screw mixing and broken screen allow gel particles to pass through.; when troubleshooting on site, verify item by item according to this mechanism, and avoid blindly adjusting the machine based only on experience
Solution
①Improve screen precision and replace regularly; ②optimize the screw mixing section; ③strengthen raw material management to prevent impurities; ④clean the accumulated material in the dead corners of the die head.; after adjustment, continuously sample to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Gel particles are the most common appearance defect of film; the three lines of defense of filtration, mixing and cleanliness are all indispensable.; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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