Creasing when laminating

[simon haysom]

Hi there.
Cold matt laminating gloss self adhesive vinyl. Yes the lam and vinyl are compatible.
Just started to get this :-( Wasn't a problem on laminating smaller sheets. This is by far the largest sheet size I have tried for quite some time. 2440mm x 1220mm. The creasers are all the worst in the centre. Could it be a low spot on the centre of the rollers?.
Its a reasonably old machine. Maybe the gap/nip is a little two wide?. Does anyone have a link showing how to measure the nip?. I occasional get problems on smaller sheets but the creasers do not look like this (different direction), and are always caused by not putting in the nip even/straight.
First time I remember getting creasers that look like this. Any thoughts/ideas appreciated.
thanks Simon

 

[simon haysom]

I think it's too wide of a nip, the folds are where the material is advancing too fast, the tighter the nip, the more the crown is compressed, the slower it advances, but I could be wrong, I do this by feel more than consciously thinking about it.
Are you running roll to roll for this, or just a large sheet? If you have rolls, the tension on the bottom roll should be even throughout, ends and center that is. I think in this case you'll find the center was very loose, and the ends super tight. I've never had much success running just sheets myself.

Yes I agree, my gut feeling is to close the nip a little but of course this will close it on the ends as well. Just large sheets. I have never done roll to roll. thanks for your help.

 

[edcooleyar]

Are you using a carrier or just print and overlam?

 

[Johnny Best]

Your not lining it up straight and flat.

 

[simon haysom]

Are you using a carrier or just print and overlam?

Just print and overlam? Didn't know there was any other way do do it.

 

[simon haysom]

Your not lining it up straight and flat.

Yes it is straight and flat. I have put sheets through that are not straight and flat and the creasers run in the opposite direction to these ones. thanks.

 

[edcooleyar]

I attach the print to a stiff carrier like sintra. Apply the lam and then trim.

 

[simon haysom]

I attach the print to a stiff carrier like sintra. Apply the lam and then trim.

Thanks for this input. I got the local laminating expert to pop in. It seems it is "mooning" Sticking to the top roller before hitting the nip. I have fixed by putting a little weigh (with my hands)
on the print just before it gets in the nip. The machine should have a long flat bar that helps tp prevent this. (was missing when I purchased). Thanks again.

 

[edcooleyar]

Thank you for the feedback. Better together