The quality of film after slitting is closely related to the process parameters set during the slitting process. So, what quality defects may occur after film slitting and what are the main causes?
The impact of slitting process on film slitting quality
The quality of film after slitting is closely related to the process parameters set during the slitting process.
From the perspective of slitting equipment, advanced slitting machines must have high-precision tension and pressure settings, tension and pressure gradients, speed adjustment, tension and pressure adjustment of each station during operation, and swing of the mother roll. When slitting, the slitting process parameters should be set and adjusted regularly according to the changes in film slitting width, film thickness, film material and slitting diameter. Otherwise, although high-quality stretch film can be produced, the final slitting product is inferior.
The quality of slitting film is usually tested by the appearance quality of the product after slitting. The quality defects in the product appearance during slitting and the main reasons for their occurrence are as follows:
1. Longitudinal stripes (longitudinal wrinkles)
The angle of the flattening roller (rubber roller) of the slitting machine is incorrect; the film thickness tolerance is large; the winding and unwinding tension is too large; the mother roll on the winder has obvious wrinkles; the film and the paper core are not well adhered.
2. There are lumps and pits on the product surface
high contact pressure; inappropriate raw material formula; large film thickness tolerance (often appears in thicker parts); the cutter is not sharp, and dust falls into the film; poor environmental hygiene, a lot of dust; high static electricity on the film; uneven surface of the paper core.
3. Dislocation of the product end face
low winding and unwinding tension; low contact pressure; unbalanced winding arm; low film surface friction coefficient; too fast slitting speed; too fast mother roll swimming speed.
4. Star-shaped wrinkles appear on the end surface
Star-shaped wrinkles caused by tight inside and loose outside are caused by improper control of tension attenuation during slitting; star-shaped wrinkles caused by loose inside and tight outside are caused by improper control of tension attenuation and pressure change or changes in thickness tolerance.
5. The surface hardness deviation of the slitting product is large
uneven film thickness; bent paper core; unbalanced contact roller pressure.
6. Warping edge
The cutter is not sharp; the contact pressure is high; the unwinding tension is high; the wrong type of cutter is selected.
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