Winder RPM Calculator
Calculate the required winder motor RPM for a given surface speed and current roll diameter.
winder
RPM
surface speed
roll
diameter
motor
conveyor
Input values
⚙
Enter values and click Calculate to see results here.
Formula
RPM = (v × 60 × 1000) / (π × D)
v = (π × D × RPM) / (60 × 1000)
Worked Example
Given: A surface speed of 100 m/min and a current roll diameter of 400 mm.
Step 1: RPM = (100 × 60 × 1000) / (π × 400) = 6,000,000 / 1256.6 = 4775 RPM
As the roll builds up, the motor must slow down. At 800 mm diameter: RPM = 2387.
Ensure your motor and VFD can handle the speed range from empty to full roll.
Engineering Notes
- Variable speed requirement: As the roll diameter changes, the motor RPM must change to maintain constant surface speed. Use a VFD with diameter feedback or PID tension control.
- Taper tension: For good winding quality, reduce tension slightly as diameter increases. Most VFDs have built-in taper tension functions.
- Motor sizing: At constant torque, power increases linearly with RPM. Size the motor for the maximum RPM × maximum torque condition.
- Encoder feedback: For precise speed control, mount an encoder on the winder shaft and use closed-loop VFD control.