Production & Quality
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Unreasonable Die Head Flow Channel Design of High-Density Polyethylene Extruder
Problem Phenomenon
The flow speed of each part of the extrudate is uneven, and the product cross-section dimensional deviation is large.
The die head flow channel design directly affects the uniformity and quality of the extrudate.
Cause Analysis
（1）The die head flow channel distribution is unreasonable, and the flow path lengths of various parts are unequal
（2）The die land length is insufficient
（3）There are dead corners in the flow channel, and the material is retained and degraded
（4）The flow channel surface finish is insufficient
（5）The die head heating is uneven
Solution
（1）Optimize the flow channel design, and adopt a coat-hanger type or branch-pipe type distributor to ensure equal flow paths
（2）Increase the die land length to stabilize the melt flow
（3）Eliminate dead corners in the flow channel, and use arc transitions at all corners
（4）Polish the flow channel surface to Ra≤0.2μm
（5）Optimize the die head heating ring layout to ensure uniform temperature
Key Takeaway
The die head flow channel design needs to ensure uniform melt distribution and no material retention, and the die head should be redesigned when necessary.
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