With the development of direct drive technology, the comparison between linear lead screw stepper motors and traditional rotary servo motors with ball screws has attracted industry attention. Some technologically advanced machining center manufacturers are now beginning to apply this technology to their high-speed machine tools.
In terms of accuracy:
Linear lead screw stepper motors, due to their simpler transmission mechanism and reduced interpolation lag, offer higher positioning accuracy, repeatability, and absolute accuracy compared to rotary servo motors and ball screws, which are easier to implement through position detection feedback control. Linear lead screw stepper motors can achieve a positioning accuracy of 0.1μm, while rotary servo motor ball screws can only reach 2-5μm. Furthermore, rotary servo motor ball screws require a lightweight transmission system across the entire closed-loop system (CNC-servo motor-backlashless coupling-thrust bearing-cooling system-high-precision rolling guides-nut seat-worktable) and high grating accuracy. To achieve higher stability, rotary servo motor ball screws require dual-axis drive, while linear lead screw stepper motors, being high-heat-generating components, require robust cooling measures. Therefore, achieving the same result with linear lead screw stepper motors comes at a greater cost.
In terms of speed:
Linear screw stepper motors have significant advantages, with speeds reaching 300 m/min and accelerations of 10g, compared to ball screws which have speeds of 120 m/min and accelerations of 1.5g. In terms of both speed and acceleration, linear screw stepper motors have a considerable advantage. Furthermore, once the heat generation issue is resolved, the speed of linear screw stepper motors can be further improved, while the speed of rotary servo motors and ball screws is limited and difficult to increase significantly.
Regarding lifespan:
Linear lead screw stepper motors, due to the installation gap and lack of contact between the moving and stationary parts, do not experience wear from the high-speed reciprocating motion of the moving part. Long-term use does not change the motion positioning accuracy, making them suitable for high-precision applications. Ball screws, on the other hand, cannot guarantee accuracy during high-speed reciprocating motion. High-speed friction causes wear on the screw nut, affecting the required motion accuracy. Therefore, they cannot meet the high-precision requirements.
