Processing Machinery
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Screw design mismatch of random copolymer polypropylene extruder
Problem Phenomenon
Product plasticization is uneven, output is low or energy consumption is high, and the screw does not match raw material characteristics.
Screw design directly affects plasticization quality, output and energy consumption.
Cause Analysis
(1) The screw compression ratio does not match the density and melting characteristics of random copolymer polypropylene
(2) The screw length-to-diameter ratio is insufficient, and the plasticizing section is not long 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 flight depth design is improper
Solution
(1) Select a screw compression ratio suitable for random copolymer polypropylene, generally 2.5-4.0
(2) The screw length-to-diameter ratio is at least 25:1 to ensure full plasticization
(3) Optimize the transition section between the screw head and the die head to eliminate stagnation zones
(4) Select suitable mixing elements (pins, barriers, etc.) according to material characteristics
(5) Ask professional screw designers to optimize flight parameters according to material characteristics
Key Takeaway
Screw design needs to match material characteristics and product requirements; customize special screws if necessary.
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