Web Tension & Winding Setup Guide

Purpose and production context

Record substrate construction, caliper under winding conditions, width after trim, roll core and maximum OD, winding direction, target line speed and the process zone being controlled. Obtain tension-per-width guidance from the material supplier, approved prior jobs or a controlled trial; do not invent a universal setting for “paper” or “film.”

Separate allowable material tension from the operating setpoint. The allowable range is a limit; the chosen setpoint must also support register, drying, coating, lamination, slitting and winding quality on the actual line.

Inputs, units and method

Use the Web Tension Force Calculator with active web width. A 0.20 N/mm setting on a 1,000 mm web produces 200 N total tension. If the web is slit before the controlled zone, calculate the force from the width present in that zone.

Check the result against the load-cell working range and wrap geometry. A sensor sized only by maximum capacity may provide poor resolution at the normal setpoint.

Definitions and distinctions

Measure core, current and finished diameters and calculate torque at each condition with the Winding Torque Calculator. Torque equals tension multiplied by roll radius, so constant tension requires rising rewind torque and falling unwind brake torque as diameter changes.

Record roll-side torque separately from motor-, brake- or clutch-side demand. Gear ratio, mechanical efficiency, service factor and regeneration limits belong to the machine engineering review.

4. Decide whether taper is required

Inspect trial rolls for starring, core crushing, telescoping, loose edges and entrained air. If the approved process needs a hard start and softer finish, use the Taper Tension Planner to document an explicit linear reference curve.

Controller definitions differ: taper may be based on diameter, radius, torque, build or a proprietary curve. Translate the documented job intent into the controller's definition rather than copying a percentage between machines.

5. Cross-check dancer loading

For a pneumatic dancer, draw the web path and count the spans loading the roller. Measure pivot-to-roller and pivot-to-cylinder effective arms at the calculation position, identify whether the cylinder acts on cap or rod area, and include every parallel cylinder.

The Dancer Pressure Calculator provides a static nominal pressure. Compare it with a load-cell reading through the dancer travel because gravity, arm angle, friction, acceleration and regulator droop can shift the real value.

6. Check ramp demand before increasing speed

The Winder Acceleration Torque Calculator adds thick-cylinder inertia to steady tension torque. Evaluate the heavy full roll and high-RPM core conditions, and repeat for deceleration if the drive must regenerate or brake the roll.

A result is not a motor selection. Verify reflected drivetrain inertia, gearbox ratio, duty cycle, thermal capacity, overspeed, emergency stop and machine safety requirements with the equipment supplier.

Worked production example

A 1,000 mm paper web uses a tested 0.20 N/mm starting setpoint: 200 N total. At 600 mm diameter it needs 60 N·m roll torque. A 150–900 mm rewind with 40% linear taper reaches 228 N at 600 mm when the core setpoint is 300 N. A separate two-span dancer at 100 N, with a 400:200 arm ratio and one 50 mm cap-end cylinder, calculates to about 204 kPa before real-machine corrections.

The operator runs at low speed, checks load-cell zero and span, records the actual dancer pressure and inspects roll build. Only then is the speed ramp increased while torque, tension and roll quality are trended.

Decision checklist

1. Material, width, caliper, core, OD and approved tension source recorded.
2. Total force converted with the correct unit basis.
3. Core, current and full-roll torque calculated.
4. Taper definition matched to the specific controller manual.
5. Load-cell range, wrap and calibration checked.
6. Dancer geometry and active cylinder area verified.
7. Acceleration and deceleration demand reviewed.
8. Low-speed trial completed with no wrinkles, slip, starring or telescoping.
9. Approved setpoints, diameter points and observations saved to the job record.

Common mistakes and cautions

Do not copy a tension or taper percentage between materials, widths or controllers without translating its unit and definition. Avoid treating pressure as tension, using diameter as radius, ignoring rod-side cylinder area, or sizing a drive from steady torque alone.

Stop the trial when the web wrinkles, slips, stretches, wanders, telescopes or damages the core. The equations explain nominal relationships; they cannot establish a safe operating window without material and machine evidence.

Related workflow

Montalvo documents tension as torque divided by radius and provides web-tension calculation resources. Maxcess describes tension, nip and torque as the interacting winding controls. Rockwell's winder handbook separates steady tension torque from acceleration demand, and Warner Electric documents dancer force and lever geometry.

• Montalvo web tension tools
• Maxcess engineering application notes
• Rockwell Winders engineering handbook
• Warner Electric tension control systems

These calculations are commissioning aids, not safe-tension recommendations or final mechanical sizing. Last reviewed: 2026-08-27.