Molding Process
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Sizing device failure of low density polyethylene extruder
Problem Phenomenon
After sizing, pipe or profile dimensional deviation is large, roundness or cross-section shape unqualified.
Sizing device failure causes reduced product dimensional accuracy.
Cause Analysis
(1) Insufficient or unevenly distributed vacuum in the vacuum sizing sleeve
(2) Sizing sleeve worn, inner diameter enlarged
(3) Insufficient cooling water flow or temperature too high
(4) Sizing sleeve not concentric with the die
(5) Scale or impurities on sizing sleeve inner wall
Solution
(1) Check vacuum pump and pipelines, ensure vacuum stable at 0.04-0.08MPa
(2) Check sizing sleeve wear, replace if beyond tolerance
(3) Increase cooling water flow, control water temperature 15-25°C
(4) Adjust the concentricity of sizing sleeve and die
(5) Regularly clean sizing sleeve inner wall, remove scale
Key Takeaway
Sizing device failure needs to be solved from three aspects: vacuum system, cooling system, and mold accuracy.
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