Molding Process
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Sizing Device Failure of Polypropylene Extruder
Problem Phenomenon
The dimensions of the pipe or profile after sizing deviate greatly, and the roundness or cross-sectional shape is unqualified.
Sizing device failure leads to reduced dimensional accuracy of the product.
Cause Analysis
(1) The vacuum degree of the vacuum sizing sleeve is insufficient or unevenly distributed
(2) The sizing sleeve is worn, and the inner diameter becomes larger
(3) The cooling water flow is insufficient or the temperature is too high
(4) The sizing sleeve is not concentric with the die
(5) There is scale or impurities on the inner wall of the sizing sleeve
Solution
(1) Check the vacuum pump and pipelines to ensure the vacuum degree is stable at 0.04-0.08MPa
(2) Check the wear of the sizing sleeve; replace it if it exceeds the tolerance
(3) Increase the cooling water flow and control the water temperature at 15-25°C
(4) Adjust the concentricity of the sizing sleeve and the die
(5) Regularly clean the inner wall of the sizing sleeve to remove scale
Key Takeaway
Sizing device failure needs to be solved from three aspects: the vacuum system, the cooling system, and mold precision.
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