Extrusion & Post
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Metallocene linear low density polyethylene blown film uneven thickness（Variant: Color/Material Change Scenario）
Fenómeno del problema
The film thickness fluctuates greatly in the circumferential or longitudinal direction, with thickness deviation exceeding ±10%.
Uneven thickness affects film mechanical properties and service performance, and may cause tracking deviation or film breakage on automatic packaging machines.In particular, when changing materials or colors, this problem is more prominent and requires key attention.
Análisis de la causa
（1） Die gap is uneven\
（2） Die circumferential temperature is uneven\
（3） Air ring cooling is uneven\
（4） Extrusion output fluctuates\
（5） Haul-off speed is unstable\
（6） When changing materials or colors, process parameter fluctuations or equipment status changes aggravate this problem
Solución
（1） Adjust the die gap, circumferential error not exceeding ±0.01mm\
（2） Check the die heater bands, ensure circumferential temperature difference does not exceed ±3°C （190-260°C range）\
（3） Check the air ring, ensure uniform air outlet, clean the air ring regularly\
（4） Stabilize the extruder screw speed and temperature\
（5） Stabilize the haul-off speed, use a high-precision haul-off control system\
（6） And do well in cleaning the transition material, paying special attention to parameter stability when changing materials or colors
Conclusión clave
Film thickness unevenness is caused by die gap, temperature or cooling unevenness, and needs to be solved from mold precision and process stability.Targeted preventive measures need to be taken in different production scenarios.
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