Extrusion & Post
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Uneven thickness of low density polyethylene cast film
Problem Phenomenon
Cast film transverse thickness deviation is large, exceeding the tolerance range.
Uneven thickness affects film winding quality and subsequent processing, and affects use performance in precision films.
Cause Analysis
(1) Uneven T-die lip gap
(2) Uneven die temperature distribution
(3) Uneven air knife airflow
(4) Uneven chill roll temperature
(5) Extrusion output fluctuation
Solution
(1) Adjust T-die lip gap, use feeler gauge to check uniformity
(2) Check die heater distribution, ensure transverse temperature difference not exceeding ±3°C (160-220°C range)
(3) Check the air knife, ensure uniform air output, clean the air knife opening
(4) Check chill roll temperature uniformity, temperature difference not exceeding ±2°C
(5) Stabilize extruder screw rotation speed and temperature
Key Takeaway
Uneven cast film thickness is caused by uneven die gap or temperature; it needs to be solved from mold accuracy and temperature uniformity.
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