Boyan we know exactly the use it's in the title "PLASMA TABLE". Also have you seen the crap that comes off plasma machine.? What do you think that will do to ballnut rotating at high speeds along static rod effectively covered in grinding paste.???

You'll be hard pushed to find many commercial plasma cutters using ballscrews other than on Z axis. 99% will be helical R&P with more than enough resolution and easily achieve high feeds without stressing anything.!