The Leadscrew Efficiency is the efficiency of a leadscrew, which is a screw used as a linkage in a machine, to translate turning motion into linear motion. Because of the large area of sliding contact between their male and female members, screw threads have larger frictional energy losses compared to other linkages. They are not typically used to carry high power, but more for intermittent use in low power actuator and positioner mechanisms. The following equation uses the torque equation to calculate efficiency: `"Efficiency"=(tanlambda)/(tan(phi+lambda))`, where:
Wikipedia (https://en.wikipedia.org/wiki/Leadscrew)