Extrusion & Post
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Unstable Cooling Line Height of Polypropylene Film
Problem Phenomenon
The cooling line (frost line) height of the blown film fluctuates greatly, and the film thickness and quality are unstable.
The cooling line height reflects the stability of cooling conditions and directly affects film performance.
Cause Analysis
(1) The air volume or air speed of the air ring is unstable
(2) The extrusion temperature fluctuates
(3) Environmental airflow interference
(4) The screw speed fluctuates
(5) The cooling air temperature fluctuates
Solution
(1) Check the air ring fan and valves to ensure stable air volume
(2) Stabilize the extrusion temperature, with fluctuation controlled within ±3°C (range 200-280°C)
(3) Install a wind shield or isolation curtain to reduce environmental airflow interference
(4) Stabilize the screw speed
(5) Use constant-temperature cooling air to reduce temperature fluctuation
Key Takeaway
Unstable cooling line is caused by fluctuations in cooling or extrusion conditions; the air ring parameters and environmental conditions need to be stabilized.
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