Complete systems are also offered with coextrusion feedblocks, flexiblelip dies, and cooling and
polishing roll stands.
The system comprised a crystalliser, dehumidifier, extrusion system,
polishing roll stack and winder.
The angular position of the first
polishing roll can be varied by 30[degrees] using an X-Y adjusting device.
At least two companies have recently made rigid
polishing roll stacks for PET film that are 8.5-ft-wide--believed to be the widest in the world.
Trio had two sheet lines with two thin ceramic-coated rolls and a third
polishing roll of nickel-plated chrome.
The belt holds the sheet under pressure for a distance that is 10 to 200 times longer than is provided by a conventional
polishing roll or air knife.
Downstream, Reifenhauser has updated its Mirex-MT-V high-performance polishing stack with three or four
polishing rolls. As an option, the roll stack can be specified with an axis crossing for the first roll to produce thin films with large widths.
In the sheet-forming area, the rolls are real
polishing rolls with high PLI [pounds per linear inch], and each nip is adjusted according to the final thickness.
Finally, the polishing stack, with
polishing rolls and post-cooling rolls arranged extremely close to each other, favours optimal sheet properties and transparency.
A ratchet-activated height-adjustment device raises and lowers the cooling and
polishing rolls relative to the sheet die.
* Grainy surface or "orange peel." When the melt is too cold, the sheet surface freezes too soon for the
polishing rolls to do an effective job.
Megatron cooling and polishing units ensure smooth transmission of power to chrome
polishing rolls for highest quality.