Recently I have been consulting on the controls for a new web handling line. We are striving to use PLI throughout this line. That is right from the cast roll to the winder.
Tension measured by load cells is standard and will be displayed in PLI. The total tension force will be divided by the web width (48 to 60 inches).
This line has a pneumatically loaded accumulator. Instead of entering the air pressures in PSI we will enter the forces in PLI and convert to PSI. The calculated tension can be calibrated with weights.
The winder lay on roll is pneumatically loaded. Instead of entering starting and taper end pressures in PSI, they will be entered in PLI with the PLC doing the conversion.
The unwind brakes do not use load cells, but we will enter the braking tension in PLI instead of PSI. The PLI will be modified by diameter to create the braking torque and this will be converted into PSI used by the unwind brakes. Naturally the unwind PLI will be calibrated.
We haven’t gone all the way yet. The corona treaters and annealers will not be scaled in KW/inch^2 this time. Of course these are not force measurements, but treatments applied to an area of web.