Extrusion & Post
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Uneven thickness of polyolefin plastomer blown films
Problem Phenomenon
The film thickness fluctuates greatly in the circumferential or longitudinal direction, and the thickness deviation exceeds ±10%.
Uneven thickness affects the mechanical properties and service performance of the film, and may cause deviation or film breakage on automatic packaging machines.
Cause Analysis
（1）The die gap is uneven
（2）The temperature in the circumferential direction of the die is uneven
（3）The air ring cooling is uneven
（4）The extrusion output fluctuates
（5）The hauling speed is unstable
Solution
（1）Adjust the die gap, with the circumferential error not exceeding ±0.01mm
（2）Check the die heating ring to ensure the circumferential temperature difference does not exceed ±3°C (180-230°C range)
（3）Check the air ring to ensure uniform air output, and clean the air ring regularly
（4）Stabilize the extruder screw speed and temperature
（5）Stabilize the hauling speed, using a high-precision hauling control system
Key Takeaway
Uneven film thickness is caused by uneven die gap, temperature, or cooling, and needs to be solved from mold precision and process stability.
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