Chrome vinyl curling

That would be my guess. I don't think metallic polyester shrinks all that much. Is it calendered laminate or cast?

 

Most likely the laminate

 

I would always stick with cast laminate on atypical materials. Calendered laminate shrinks and if the film it's laminating doesn't shrink to a similar degree, you're bound to have some issues.

 

How close are you cutting to the printed part of the vinyl?
If you read the R-Tape documentation, they recommend leaving 5mm of unprinted area around printed parts of the vinyl or it will curl.
The only way we got around this was printing with UV ink and not solvent. No curling after that. We laminate with 3M 8518 cast.

 

No, it's likely that you need slightly more unprinted vinyl around the edges... cutting directly through a printed portion is near guaranteed to curl.
I can't find a copy of the old VinylEFX documentation but I'm fairly sure it stated 5mm of unprinted area to prevent curl.

 

You need to use Cast laminate over Mylar (Chrome) if you lam it. Otherwise, use a Liquid U.V. protection such as ClearShield.

 

Print directly to the Chrome and lam with cast material. More layers leaves more room for possible failures X 3+. Don't try to re-invent the wheel here.

 

try the cast lam but best bet is to get a polyester/mylar lam.
years ago when we first started doing digital printing we had polyester lam we used for our silk screened items so we just used that on the digital print items then we had the reverse of your problem the vinyl would shrink but no the lam. live and learn