Molding Process
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Sizing device failure of linear low-density polyethylene extruder
Problem Phenomenon
After sizing, the pipe or profile has large dimensional deviation, and roundness or cross-sectional shape is unqualified.
Sizing device failure reduces product dimensional accuracy.
Cause Analysis
(1) The vacuum sizing sleeve has insufficient vacuum or uneven distribution
(2) The sizing sleeve is worn and the inner diameter becomes larger
(3) Cooling water flow is insufficient or temperature is too high
(4) The sizing sleeve is not concentric with the die
(5) There is scale or impurities on the sizing sleeve inner wall
Solution
(1) Check the vacuum pump and pipelines to ensure stable vacuum at 0.04-0.08MPa
(2) Check sizing sleeve wear; replace if it exceeds tolerance
(3) Increase cooling water flow and control water temperature at 15-25°C
(4) Adjust the concentricity of the sizing sleeve and the die
(5) Regularly clean the sizing sleeve inner wall to remove scale
Key Takeaway
Sizing device failure needs to be solved from three aspects: vacuum system, cooling system and mold precision.
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