Molding Process
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Random copolymer polypropylene extruder sizing device failure
Problem Phenomenon
After sizing, the pipe or profile has large dimensional deviations, and the roundness or cross-sectional shape is unqualified.
Sizing device failure causes product dimensional accuracy to decrease.
Cause Analysis
（1）The vacuum sizing sleeve vacuum degree is insufficient or unevenly distributed\
（2）The sizing sleeve is worn, the inner diameter becomes larger\
（3）Cooling water flow insufficient or temperature too high\
（4）The sizing sleeve is not concentric with the die\
（5）The sizing sleeve inner wall has scale or impurities
Solution
（1）Check the vacuum pump and piping, ensure the vacuum degree is stable at 0.04-0.08MPa\
（2）Check sizing sleeve wear, replace if beyond tolerance\
（3）Increase cooling water flow, 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, 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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