Extrusion & Post
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Metallocene linear low density polyethylene cast film uneven thickness（Variant: Startup Commissioning Scenario）
Fenómeno do 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.In particular, during new machine commissioning or the initial startup period, this problem is more prominent and requires key attention.
Análise das causas
（1） The T-die lip gap is uneven\
（2） The die temperature distribution is uneven\
（3） The air knife airflow is uneven\
（4） The cooling roll temperature is uneven\
（5） Extrusion output fluctuates\
（6） During new machine commissioning or the initial startup period, process parameter fluctuations or equipment status changes aggravate this problem
Solução
（1） Adjust the T-die lip gap, use a feeler gauge to check uniformity\
（2） Check the die heater distribution, ensure transverse temperature difference does not exceed ±3°C （190-260°C range）\
（3） Check the air knife, ensure uniform air outlet, clean the air knife opening\
（4） Check the cooling roll temperature uniformity, temperature difference not exceeding ±2°C\
（5） Stabilize the extruder screw speed and temperature\
（6） And do well in parameter recording and archiving, paying special attention to parameter stability during new machine commissioning or the initial startup period
Conclusão principal
Cast film thickness unevenness is caused by die gap or temperature unevenness, and needs to be solved from mold precision and temperature uniformity.Targeted preventive measures need to be taken in different production scenarios.
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