Processing Machinery
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Screw Design Mismatch of High-Density Polyethylene Extruder
Problem Phenomenon
The product plasticization is uneven, the output is low or the energy consumption is high, and the screw does not match the raw material characteristics.
The screw design directly affects the plasticization quality, output, and energy consumption.
Cause Analysis
（1）The screw compression ratio does not match the density and melting characteristics of high-density polyethylene
（2）The screw length-to-diameter ratio is insufficient, and the plasticizing section length is not enough
（3）The design of the transition section between the screw head and the die head is improper
（4）The screw mixing elements are not suitable for this material
（5）The screw thread depth design is improper
Solution
（1）Select a screw compression ratio suitable for high-density polyethylene, generally 2.5-4.0
（2）The screw length-to-diameter ratio is at least 25:1 to ensure sufficient plasticization
（3）Optimize the transition section between the screw head and the die head to eliminate material retention areas
（4）Select suitable mixing elements (pins, barriers, etc.) according to the material characteristics
（5）Ask professional screw designers to optimize the thread parameters according to the material characteristics
Key Takeaway
The screw design needs to match the material characteristics and product requirements, and a special screw should be customized when necessary.
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