5.3
SUPPLY ROLL TENSION AND OTHER
ADJUSTMENTS
1. Now adjust the supply roll tension. First loosen all four supply roll tension
knobs, then tighten them (turn clockwise) until they just begin to press on the
springs. Another ¼ to ½ turns (one turn equals 360 degree rotation of the
knob) of tension on all four knobs is usually sufficient for 1.5 or 3 mil film.
More tension is required for 3-mil or heavier films. More tension is also
required as the width of the film increases.
The best way to do the fine adjustment or readjustment of supply roll tension
is to observe the film going over the shoes while the drive is on. Turn on the
drive. Both laminating and pull rollers must be closed and locked. Adjust the
speed to match the expected lamination work.
If the supply roll tension is too loose, some wrinkles can be observed at the
leading edges of both shoes. Lines of air may also be observed between the
film and the shoes at the leading edges. The visual effect caused by air
between the film and the shoes is known as “waterfalling.”
If some wrinkles and/or a waterfalling effect extend about 1/3 of the way
across both shoes from the leading edges toward the trailing edges, the
supply roll tension is close to “perfect” for most jobs. (The leading edge of the
top shoe is the top edge. The leading edge of the bottom shoe is the bottom
edge. The trailing edges of both shoes lead into the “nip”, where the two
laminating rollers come together.)
If the film is going over both shoes without any wrinkling or waterfalling,
supply roll tension is too high. If the wrinkling is extending into the nip,
supply roll tension is too low. Supply roll tension is not an absolute
adjustment. The acceptable range of tension settings is fairly wide. If little
wrinkling or waterfalling is visible on the leading edges, tension could be
reduced a little. If the wrinkling or waterfalling is extending to the trailing
edges, tension could be increased a little. Make sure that top and bottom
rollers have about the same tension.
2. What we call the “drape test” is an effective way to evaluate supply roll
tension simply by examining the laminate. Run about two feet of film out the
back of the machine. Cut the web of film at the exit point. Hold the two
corners of the film on the side where it was cut away from the laminator with
the bottom side facing you. Let it drape straight down. If the film hangs
perfectly straight and flat, or if there’s a small amount of curl in one of the
bottom corners, the supply roll tension is set about right.
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