Molds & Tooling
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Random copolymer polypropylene pipe special material (Nordic standard） extruder die head runner design unreasonable（Variant: Mass Production Scenario）
Problem Phenomenon
The flow velocity of the extrudate at various parts is uneven, and the product cross-sectional dimension deviation is large.
The die head runner design directly affects the uniformity and quality of the extrudate.In particular, during continuous mass production, this problem is more prominent and requires key attention.
Cause Analysis
（1）The die head runner distribution is unreasonable, the flow path lengths at various parts are unequal\
（2）The die land length is insufficient\
（3）The runner has dead corners, material stagnates and degrades\
（4）The runner surface finish is insufficient\
（5）The die head heating is uneven\
（6）In continuous mass production, process parameter fluctuations or equipment status changes aggravate this problem
Solution
（1）Optimize the runner design, adopt a coat-hanger type or manifold type distributor to ensure equal flow path lengths\
（2）Increase the die land length, stabilize melt flow\
（3）Eliminate runner dead corners, use arc transitions at all corners\
（4）Polish the runner surface to Ra≤0.2μm\
（5）Optimize the die head heater band layout, ensure uniform temperature\
（6）And establish standardized work instructions, paying special attention to parameter stability in continuous mass production
Key Takeaway
The die head runner design needs to ensure uniform melt distribution and no stagnant material; if necessary, redesign the die head.Targeted preventive measures need to be taken in different production scenarios.
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