Material Drying
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Rough inner and outer walls of general-purpose polyethylene pipes
Problem Phenomenon
The inner wall or outer wall surface of the pipe is rough, with visible stripes or particles.
Rough pipe wall increases fluid resistance and affects conveying efficiency, and may affect hygienic performance in water supply pipes.
Cause Analysis
（1）The die or mandrel temperature is low, and the melt surface is rough
（2）The finish of the die or mandrel surface is insufficient
（3）The sizing sleeve is worn or the surface is rough
（4）The melt temperature is low, and the flowability is poor
（5）The compressed air has a high water content, affecting the inner wall
Solution
（1）Appropriately raise the die and mandrel temperature to the higher value within the range of 160-260°C
（2）Polish the die and mandrel to Ra≤0.2μm, with chrome plating
（3）Check the sizing sleeve, and replace it if it is worn or rough
（4）Appropriately raise the barrel temperature to a reasonable value within the range of 160-260°C
（5）Add a drying and filtering device to the compressed air
Key Takeaway
Rough pipe wall is caused by low mold temperature or poor surface condition, and needs to be solved from temperature control and mold maintenance.
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