Extrusion & Post
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Unstable Discharge/Surging in Polypropylene Extrusion Process
Problem Phenomenon
The discharge amount of the extruder varies from time to time, the extrudate is uneven in thickness, and periodic surging occurs.
Unstable discharge directly affects the dimensional accuracy and quality consistency of the product.
Cause Analysis
(1) The conveying of the screw feeding section is unstable, and the solid bed breaks
(2) The feeding of the hopper is not smooth, and the raw material bridges
(3) The barrel temperature is set improperly, with the feeding section temperature too high or too low
(4) The screw speed fluctuates
(5) The raw material particle size is uneven or contains too much powder
Solution
(1) Optimize the barrel temperature distribution, and appropriately reduce the feeding section temperature to prevent premature melting
(2) Install a vibrator on the hopper to prevent bridging and ensure continuous feeding
(3) Reasonably set the temperature of each section of the barrel to ensure it is within the range of 200-280°C
(4) Check the extruder drive system and stabilize the screw speed
(5) Control the uniformity of raw material particles, with the powder ratio not exceeding 5%
Key Takeaway
Unstable discharge is caused by unstable solid conveying, and the barrel temperature and feeding system need to be optimized.
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