Lead screw linear actuators are motorized assemblies that use a threaded screw and mating nut to convert rotary motion into controlled linear movement, typically with NEMA hybrid stepper motors for programmable positioning. Anti-backlash nuts maintain preload against the lead screw threads to reduce axial clearance and preserve positioning accuracy as wear occurs. PTFE-lined nut surfaces further reduce friction and wear while supporting smooth motion and long service life.
PBC Linear LS lead screw linear motor actuators combine precision-rolled lead screws with patented Constant Force Technology™ anti-backlash nuts. Metric screw diameters include 6mm and 10mm, with leads from 1mm to 25mm depending on diameter and motor size. Imperial options include 3/16", 1/4", and 3/8" screw diameters with leads from 0.05" to 0.50". The actuators are available in NEMA 11, 14, 17, and 23 frame sizes. (PBC Linear Leadscrew Catalog)
A captive lead screw actuator keeps the motor stationary while an internal rotating nut drives a non-rotating screw to extend or retract from the motor, moving a load attached to the screw end. Because the screw is retained within the motor assembly, available travel is limited by the space inside the motor.
A non-captive lead screw actuator uses a screw that passes completely through the motor, allowing substantially longer travel. In a common configuration, the screw is supported at both ends and restrained from rotating while the motor, integrated nut, and attached load travel along it. In another arrangement, the motor remains stationary while the screw moves axially through the rotating nut and carries a load attached to its end. These options allow either the motor assembly or the screw to provide the moving output.
Stepper motor control supports straightforward direction changes and repeatable positioning cycles, making LS actuators suitable for compact automation, medical devices, electronics manufacturing, and other applications requiring low backlash and dependable linear motion. Non-captive actuators are often paired with a separate linear guide to support the load, maintain alignment, increase stiffness, and resist side and moment loads.
