Free Engineering Tool #077
Ball Screw Calculator — Torque, Critical Speed & Life
Enter lead, nominal diameter, axial load, and speed to calculate drive torque, efficiency, critical speed, and rated life. Calculations are based on general ball-screw engineering practice and manufacturer-catalogue methods; ball screw terminology and acceptance tolerances are defined in the ISO 3408 standard series.
Results
Drive Torque
Critical Speed
Life
Apply 0.8 safety factor to critical speed. Use fixed-fixed supports where possible.
T=F·l/(2πη), η≈0.90 for ball screws.
Ball: 0.85–0.95. ACME: 0.25–0.50.
Below 80% Ncrit. Larger dia, shorter length.
L10=(Ca/F)³×10⁶ rev. Cubed inverse.
Fixed-fixed: 4.73. Fixed-supported: 3.93.
The procedures described on this page were developed and field-tested by the Vibromera team using the Balanset-1A, a portable dual-channel balancer and vibration analyzer for on-site rotor balancing.
