Extrusion & Post
1 views
PE Film Thickness Deviation
Problem Phenomenon
PE film shows periodic machine-direction (MD) thickness fluctuations or transverse-direction (TD) one-side thick one-side thin, resulting in uneven strength and heat sealing after bag making.
Cause Analysis
MD deviation mostly comes from extrusion output pulsation or haul-off speed fluctuation; TD deviation mostly comes from uneven die lip gap, transverse die temperature unevenness, asymmetric air ring/cooling or off-center bubble.
Solution
①MD direction: stabilize the extrusion and haul-off, and monitor the screen pack pressure differential; ②TD direction: adjust the die lip bolts, calibrate the temperature of each die zone, cool uniformly and center the bubble; ③configure online thickness measurement with closed-loop control; ④establish thickness SPC monitoring.
Key Takeaway
PE film thickness is managed by direction: for MD check the stability of extrusion and haul-off, for TD check the symmetry of the die lip and temperature/air ring; closed-loop thickness measurement is standard, and adjusting the die lip by hand feel has long been unable to keep up with the quality requirements.
Was this helpful?
0 people found this helpful
Thank you for your feedback!