Complete systems are also offered with coextrusion feedblocks, flexiblelip dies, and cooling and polishing roll
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.