A stepper motor linear actuator is a device that converts the rotary motion inside a motor into a linear motion. Inside the rotor, there is a threaded precision nut instead of a shaft. The shaft is instead replaced by a lead-screw. The linear motion is achieved by the engagement of the nut and the lead-screw.

Types of linear actuators

Linear actuators include non-captive linear actuators, captive linear actuators and external linear actuators.

The non-captive linear actuator has a lead screw running through the motor, there is no defined stroke limit but it must be attached to a

component that will not rotate. The lead-screw can be made to extend and retract without rotating.

The captive linear actuator has the same nut built into the body as the non-captive linear actuator, the screw shaft is connected to the spline shaft, and the spline and the spline sleeve on the front of the motor fit together to prevent rotation.

The external linear actuator achieves linear motion by the engagement of a screw and nut external to the motor, and somehow preventing the screw and nut from turning relative to each other.

Advantages of stepper motor linear actuators

Conversion from rotary to linear directly inside the motor makes a lot of sense as it greatly simplifies the design of rotary to linear applications. In contrast, if a rotary motor is used as the power source, conversion to linear motion requires the use of gears, cam mechanisms and belts or wires. This makes stepper motor linear actuators ideal for applications requiring high resolution and precise motion.

Due to the simplicity of the drive mechanism, the positioning accuracy, repeatable precision and absolute precision of stepper motor linear actuators will be higher and easier to achieve than a combination of rotary motor and screw. This makes stepper motor linear actuators ideal for applications requiring high resolution and precise motion.

Related applications

These precise and reliable stepper motor linear actuators can be found anywhere, such as in homes, offices, hospitals, factories and many other places. They are used in many devices such as blood analyzers and other medical instrumentation, automated stage lighting, imaging equipment, HVAC equipment, valve control, printing equipment, X-Y tables, integrated chip manufacturing, inspection and test equipment.


STEPPERONLINE offers a wide range of sizes of linear actuators and accessories to suit a variety of applications in different industries. We also offers customized services for some of the customer's special requirements, such as customized threads, special nuts or lead-screw machining. In addition, new linear actuators are always being developed to provide motion solutions for a wider range of industries.