Processing Machinery
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Unreasonable head flow channel design of linear low-density polyethylene extruder (variant: strengthened measures)
Problem Phenomenon
The flow velocity of various parts of the extrudate is uneven, and the product cross-sectional dimension deviation is large.
Head flow channel design directly affects the uniformity and quality of the extrudate.
Especially, additional attention is needed on top of the original basis; this problem is more prominent and requires focused attention.
Cause Analysis
(1) Unreasonable head flow channel distribution; flow path lengths of various parts are unequal
(2) Insufficient die land length
(3) Dead zones exist in the flow channel, where material stagnates and degrades
(4) Flow channel surface finish is insufficient
(5) Head heating is uneven
(6) On top of the original basis, additional attention is needed as process parameter fluctuations or equipment condition changes aggravate this problem
Solution
(1) Optimize flow channel design, using coat-hanger or manifold distributors to ensure equal flow path lengths
(2) Increase the die land length to stabilize melt flow
(3) Eliminate flow channel dead zones; all corners use arc transitions
(4) Polish the flow channel surface to Ra≤0.2μm
(5) Optimize the head heating band layout to ensure uniform temperature
(6) And strengthen process monitoring; on top of the original basis, additional attention is needed to pay special attention to parameter stability
Key Takeaway
Head flow channel design needs to ensure uniform melt distribution and no stagnation; redesign the head if necessary.
In different production scenarios, targeted preventive measures need to be taken.
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