Taper Tension Planner

Calculate a transparent linear reduction in web tension as a rewind grows from core to full diameter.

Core diameter (mm)Use the loaded core outside diameter.Full roll diameter (mm)Use the approved finished OD or machine clearance limit.Current roll diameter (mm)Must fall between core and full diameter.Starting tension at core (N)Use a tested job setpoint, not a generic material value.Linear taper at full roll (%)40% means full-roll tension is 60% of starting tension.

Enter roll diameters, starting tension and taper.

What this planner solves

A hard start can stabilize the core while excessive full-roll tension can star, crush or telescope sensitive webs. This planner exposes one explicit linear taper instead of hiding the curve behind a controller percentage.

Inputs and units

All diameters use the same millimetre basis. Starting tension is total newtons across the web. Taper is the total percentage reduction reached at the full-roll diameter.

Calculation method

Build fraction = (current diameter − core diameter) ÷ (full diameter − core diameter). Target tension = start tension × [1 − taper × build fraction]. Torque then equals target tension × current radius.

Worked production example

From a 150 mm core to 900 mm finished OD, a 600 mm roll is 60% through its diameter build. Starting at 300 N with 40% full-roll taper produces 228 N and 68.4 N·m at that point.

How to use the result

Compare several diameters before commissioning, record the approved curve and inspect roll hardness, starring and telescoping during the trial. A controller may express taper against radius, diameter, torque or build, so map its definition first.

Common production mistakes

Do not assume every controller uses this linear definition. Avoid using free-state material thickness to infer a diameter that the machine already measures more accurately.

Assumptions and limitations

The model is intentionally linear and does not prescribe an ideal taper. Material modulus, entrained air, nip load, caliper variation, winding method and core strength must be proven on the actual line.

Related workflow and sources

Maxcess describes taper as a hard start transitioning to a softer finish, while Rockwell notes that center-driven winders apply taper as diameter grows. Continue with Winding Torque. Maxcess designer's notebook. Last reviewed: 2026-08-27.