Extrusion & Post
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Random copolymer polypropylene pipe special material (Nordic standard） extruded products dimensional fluctuation
Problem Phenomenon
The outer diameter, wall thickness or width of the extruded product fluctuates periodically or randomly in the longitudinal direction.
Dimensional fluctuation affects product fit accuracy and service performance, common in pipe and profile extrusion.
Cause Analysis
（1）Screw speed unstable, output fluctuates\
（2）Haul-off speed unstable, not matching the extrusion speed\
（3）Barrel temperature fluctuates greatly, melt viscosity changes\
（4）Raw material feeding uneven, discharge fluctuates\
（5）Cooling water temperature or flow fluctuates
Solution
（1）Check the extruder drive system, stabilize the screw speed\
（2）Check the haul-off machine speed control system, ensure stable haul-off speed\
（3）Stabilize the barrel temperature, fluctuation controlled within ±3°C (200-220°C range)\
（4）Check hopper discharge, ensure continuous and uniform feeding\
（5）Stabilize cooling water temperature and flow, add a constant temperature device if necessary
Key Takeaway
Dimensional fluctuation is caused by unstable extrusion or hauling, requiring systematic stabilization of all process parameters.
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