In film and paper laminating, the nip station is the pair of rolls that presses the coated web to the second web. Glue that is still wet, or a dried heat-seal that you reactivate, has to wet both surfaces here. Miss the nip setup and you get tunnels, wrinkles, starved glue, or crush.
What the nip does
One roll is usually steel. The other is rubber-covered. The rubber deforms and makes a contact patch (the nip width). Wider patch means longer dwell at a given line speed. Dwell is how long the adhesive is under pressure before the webs leave the rolls.
Wet-bond laminating nips while the adhesive is still wet. Paper can drink water; film cannot. Dry-bond dries the adhesive first, then nips, often with heat. Extrusion laminating puts a molten polymer in the nip instead of a liquid adhesive.
Rolls and hardness
Rubber hardness is Shore A. Softer covers make a wider nip and are more forgiving on caliper variation. Harder covers make a narrower, higher-pressure patch and hold a sharper line. Cover diameter, crown, and whether the roll is driven all change the patch.
Keep the cover clean. Dried adhesive on the rubber prints a repeating void. A damaged cover prints a repeating crush or skip.
Pressure, wrap, and speed
Nip pressure is not “more is better.” Too light and you starve the bond or trap air. Too heavy and you squeeze adhesive out, crush paper, or stretch film. Match pressure to caliper, adhesive viscosity, and coat weight.
Wrap is how much web contacts a roll before the nip. More wrap can preheat or pre-smooth. It can also wrinkle a film that wants to wander. Infeed tension and the idler just before the nip matter as much as the load on the rolls.
Speed shortens dwell. If you raise speed, you may need more coat weight, a faster-wetting grade, more heat, or a slightly wider nip — not only more pressure.
Defects
Tunnels and bubbles. Air not squeezed out, or adhesive too dry or too viscous to flow. Check coat weight, open time, and nip width.
Wrinkles. Uneven tension, misaligned rolls, or a film that stretches on a hot roll. Square the station before you change adhesive.
Starved glue line. Coat weight too low, or the nip squeezed the adhesive out to the edges. Look at the squeeze-out bead.
Curl. Moisture into paper, or two webs with different stretch. Dry-bond and balanced tensions help more than a harder nip.
Send the two webs, coat weight, and line speed. Call 800-249-0337.
Related Cattie grades
General plant guidance only — not a substitute for your process, SDS/TDS, or line trials. Call 800-249-0337 to match a grade.