Processing Machinery
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Unreasonable die head flow channel design of random copolymer polypropylene pipe special material extruder (Variant: mass production scenario)
Problem Phenomenon
The flow speed of each part of the extrudate is uneven, and the cross-sectional dimension deviation of the product is large.
The die head flow channel design directly affects the uniformity and quality of the extrudate.
In particular, in continuous mass production, this problem is more prominent and needs key attention.
Cause Analysis
（1）The die head flow channel distribution is unreasonable, and the flow path lengths of each part are unequal
（2）The die land length is insufficient
（3）There are dead corners in the flow channel, and the material stays and degrades
（4）The finish of the flow channel surface is insufficient
（5）The die head heating is uneven
（6）In continuous mass production, process parameter fluctuations or equipment status changes have aggravated this problem
Solution
（1）Optimize the flow channel design, and use a coat-hanger or branch pipe distributor to ensure that each flow path is equal in length
（2）Increase the die land length to stabilize the melt flow
（3）Eliminate the dead corners of the flow channel, and use arc transitions at all corners
（4）Polish the flow channel surface to Ra≤0.2μm
（5）Optimize the arrangement of the die head heater bands to ensure uniform temperature
（6）And establish standardized work instructions, with special attention to parameter stability in continuous mass production
Key Takeaway
The die head flow channel design needs to ensure uniform melt distribution and no stagnation, and the die head needs to be redesigned if necessary.
In different production scenarios, targeted preventive measures need to be taken.
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