It's a raceway that contains a rolling bearing, and the ball moves up and down the screw. Ball bearings reduce friction. Recently, I have published some blog articles about ball screw. Some of the information is basic, but it also includes preloading and friction. In addition, they are likely to expand this topic in future articles. Watch the video below if you like. First of all, the cost of the guide screw is lower than that of the ball screw. Unlike the ball screw, the guide screw is of a type, and does not need a braking system. The ball screw may operate vertically. The ball screw is more efficient than the guide screw, allowing small torque and small motor. The guide screw also generates more heat. The guide screw needs to be changed more frequently than the ball screw. Based on the empirical formula of rolling bearing friction torque, a new model for predicting the friction torque and mechanical efficiency of ball screw is proposed in this paper. At the same time, a novel measurement system is constructed to obtain the mechanical efficiency of ball screw, in which the axial load and speed are stable and adjustable. The experimental results show that the mechanical efficiency of ball screw increases with the increase of axial load. In addition, the model constructed in this paper is suitable for relatively high speed conditions. The new model can be used to obtain the friction torque and mechanical efficiency of ball screw.