Extrusion & Post
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Uneven thickness of linear low-density polyethylene cast film (variant: strengthened measures)
Fenómeno del problema
The transverse thickness deviation of the cast film is large, exceeding the tolerance range.
Uneven thickness affects film winding quality and subsequent processing, and affects service performance in precision films.
Especially, additional attention is needed on top of the original basis; this problem is more prominent and requires focused attention.
Análisis de la causa
(1) The lip gap of the T-die is uneven
(2) Die temperature distribution is uneven
(3) Air knife airflow is uneven
(4) Cooling roll temperature is uneven
(5) Extrusion output fluctuates
(6) On top of the original basis, additional attention is needed as process parameter fluctuations or equipment condition changes aggravate this problem
Solución
(1) Adjust the T-die lip gap and check uniformity with a feeler gauge
(2) Check the die heater distribution to ensure the transverse temperature difference does not exceed ±3°C (190-250°C range)
(3) Check the air knife to ensure uniform air output, and clean the air knife opening
(4) Check cooling roll temperature uniformity, with temperature difference not exceeding ±2°C
(5) Stabilize extruder screw speed and temperature
(6) And strengthen process monitoring; on top of the original basis, additional attention is needed to pay special attention to parameter stability
Conclusión clave
Uneven cast film thickness is caused by uneven die gap or temperature and needs to be solved from mold precision and temperature uniformity.
In different production scenarios, targeted preventive measures need to be taken.
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