I have a winder that we use to rewinder paper at our paper mill. The way we check tension in the roll (to avoid a soft roll) is to see how much of a razor knife blade you can push into the roll. If you can get less than 1/4" its tight enough for us (recycled medium mill 58" roll diameter).
We run the pneumatic brake on our winder to the torque of our winder drives (drum winder with shaft). We used to use load cells, but this would produce a nice tight sheet with 2 less pieces of equipment to brake.
I use a PID loop in ControlLogix to vary the signal to the I/P to the pneumatic brake so that the wiinder will run consistent tight rolls. The nice thing on this set-up is that when the brake is running at 100% for 50% of the roll, a message is displayed so the operator can check the brake pressure on the gauges (make sure no air leak) and get the mechanics to change/shim the brake pads.
