Extrusion & Post
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LDPE Blown Film Thickness Band
Problem Phenomenon
The film shows thickness bands at fixed positions, and the roll surface bulges like wood grain after winding
Cause Analysis
Uneven die heating, air ring blockage, and silicone grease accumulation all cause different melt flow rates at fixed positions to form thickness bands; when the die does not rotate, the thickness band accumulates at fixed positions on the roll surface
Solution
① Rotate the die and air ring to distribute the thickness band uniformly; ② clean air ring blockage and grease accumulation; ③ check the integrity of the die heating band; after adjustment, take continuous samples to verify the effect, and resume mass production only after confirming stability
Key Takeaway
Thickness bands rely on rotation for equalization; dispersing fixed defects by motion is a classic solution for blown film winding quality; after confirming effectiveness, solidify the parameters and practices into the work instruction to prevent recurrence
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