Reasons for uneven thickness of BOPET film

 ① The rotation speed of the extruder and metering pump is unstable; ② The rotation speed of the cooling drum is unstable, vibrating up and down and eccentric; ③ The feed amount, slice temperature, and final product degree fluctuate, and sometimes there is "screw holding" " situation; ④ Resin melt viscosity changes; ⑤ Longitudinal stretching speed, temperature and magnification are unstable.

① uneven distribution of resin melt viscosity and temperature along the cross-section; ② local temperature fluctuations at the die lip; ③ thickness measurement feedback is lagging and insensitive; ④ process from thick sheet casting to longitudinal stretching In the process, by Due to uneven temperature or poor synchronization, the physical structure (hardness, orientation, etc.) is inconsistently distributed along the transverse direction, and the thickness developed during transverse stretching is uneven; ⑤ Each section of the infrared lamp tube used in the longitudinal stretching machine The power is inconsistent.