Material Drying
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Rough inner and outer walls of linear low-density polyethylene pipes (variant: strengthened measures)
Problem Phenomenon
The inner or outer wall surface of the pipe is rough, with visible streaks or particles.
Rough pipe walls increase fluid resistance and affect conveying efficiency, and may affect hygiene performance in water supply pipes.
Especially, additional attention is needed on top of the original basis; this problem is more prominent and requires focused attention.
Cause Analysis
(1) Die or mandrel temperature is on the low side, and the melt surface is rough
(2) Die or mandrel surface finish is insufficient
(3) The sizing sleeve is worn or has a rough surface
(4) Melt temperature is on the low side and fluidity is poor
(5) Compressed air has high water content, affecting the inner wall
(6) On top of the original basis, additional attention is needed as process parameter fluctuations or equipment condition changes aggravate this problem
Solution
(1) Appropriately increase die and mandrel temperature to the higher value within the 190-250°C range
(2) Polish the die and mandrel to Ra≤0.2μm, with chrome plating treatment
(3) Check the sizing sleeve; replace if worn or rough
(4) Appropriately increase barrel temperature to a reasonable value within the 190-250°C range
(5) Add a drying and filtering device to the compressed air
(6) And strengthen process monitoring; on top of the original basis, additional attention is needed to pay special attention to parameter stability
Key Takeaway
Rough pipe walls are caused by low mold temperature or poor surface condition and need to be solved from temperature control and mold maintenance.
In different production scenarios, targeted preventive measures need to be taken.
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