Work out lead screw torque instantly with clear inputs, formula shown and shareable results.
Lead screw torque combines the useful lifting component with thread friction: T = (F d/2)(tan(lambda) + mu)/(1 - mu tan(lambda)). Efficiency of an ACME screw is typically 20-40%, and if the backdriving torque comes out negative the screw is self-locking and will hold the load without brake.
Lead screw torque
T = (F x d/2) x (tan(lambda) + mu) / (1 - mu tan(lambda)), lambda = atan(lead / pi d)
When the friction coefficient exceeds the tangent of the lead angle. Fine-pitch ACME screws usually are; ball screws almost never are.
Efficiency of 90% or more, so far less motor torque and heat. The trade is cost, backlash management and the need for a brake on vertical axes.