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How Do Servo Actuators Work?

Admin | May 31st, 2022

Servo motor-controlled actuators provide precise and repeatable movements for industrial machines. They are utilized across many industrial applications, including those requiring high-precision positioning and cycling. But how exactly do these actuators work, and what advantages might they bring to your project?

KEB develops world-class products that work in tandem with actuators to drive performance, including servo motors and brakes for electric linear actuators. To help you decide whether servo actuators are the right fit for your unique application, let’s take a closer look to understand how they function.


electric motor linear actuator animation example
Example of an electric linear actuator


Understanding Linear & Rotary Servo Actuators

In machines, servo actuators provide the exact torque, speed, and target position required for an application based on its specifications. This level of precision unlocks greater productivity while reducing the energy consumption of the system overall.

Two of the most common types of servo actuators are linear and rotary. A linear servo actuator moves parts of a machine in a straight line, typically back and forth. These actuators exert a mechanical force that creates simple linear motion. A rotary servo actuator moves parts in a circular motion, either a set number of degrees or round and round infinitely.

Electric motors convert electrical energy to mechanical energy.  Most motors (e.g. induction) provide a rotational torque on an output shaft.  This rotating output is useful for many machine applications like mixers, fans, saws, and pumps.  In rotary actuator applications, a motor that is equipped with a position sensor can position its payload in a circular fashion.  This is particularly useful for robotic and pick and place applications.

Linear movements in machines can be achieved with a number of different mechanisms including belts, chains, and ballscrews.  In general, we can break down linear servo actuators into several common parts.  First, there is the rotary synchronous servo motor that provides a relatively high-speed rotational output.  Second, gearboxes can be used which provide a torque increase.  Finally, the rotating shaft is then converted to a linear movement using a belt, leadscrew, or ballscrew assembly.  Each of these linear actuator technologies has its own advantages and tradeoffs with regard to performance and cost.


What Is the Purpose of the Actuators?

At the basic level, actuators create movement in machines by converting supplied energy into mechanical force. Depending on the type of movement required, your application may work best with a rotary or linear servo actuator. It really depends on how you need the parts or objects involved with your machine to move.


Rotary servo actuators are often more flexible because the circular motion they create can be converted into linear motion. For example, pulleys and belts can be used to convert the circular motion of a rotary servo actuator into linear movement, allowing objects to pass from point X to Y. In any case, we use actuators to achieve the same common goal: creating effective mechanical movement in a machine.


KEB Servo Motor DL4
KEB Servo motors for actuator applications


Advantages of Servo Actuators

Superior performance: A servo actuator delivers excellent torque, speed, and power across its lifespan. This dependable performance makes servo actuators a natural fit for even the most demanding industrial applications and environments.


Precision control: Servo actuators enable highly accurate motion control, a mandatory in applications requiring precision and near-perfect repeatability.


Compact size: A linear or rotary servo actuator is remarkably size efficient, making it ideal for applications with space or weight restrictions. For example, machine builders can integrate servo actuators to create more compact, lightweight robotics systems.


Low energy consumption: A rotary or linear servo actuator offers high power density, which reduces the overall energy consumption of the machine or system. This provides an opportunity to build more energy-efficient, sustainable solutions in many industries.


Applications for Servo Actuators

Thanks to their efficiency, precision control, and general versatility, servo actuators support a wide variety of industrial applications. Here are some of the most common use cases for servo actuators in the industrial world:


Material Handling icon

  1. Material Handling

Precise automation is very important in material handling, where speed, accuracy, and care are crucial to meet consumer demands. A linear or rotary servo actuator grants material handling systems a new caliber of control, ensuring materials are transported quickly and safely to their proper destinations. These solutions can be elevated with functional safety tools such as emergency brakes and Safety PLCs to maximize safety while keeping the supply chain in a fluid motion.


  1. Medical Devices

Medical devices require pinpoint accuracy to support patient safety, comfort, and care outcomes. This is where a rotary or linear servo actuator excels. Medical tools requiring precise motion control, such as patient lifts, can harness servo actuators to ensure the proper positioning of objects or patients for treatment. These medical applications can be further improved with purpose-built brakes and clutches.


icon of a robotic arm

  1. Robotics

Robotics is an ascendant force in automation, sweeping diverse industrial applications from metalworking and spot welding to packaging and plastics. With servo actuators, machine builders can create more dependable, efficient robotic systems that move tools, parts, or materials with unmatched precision.


KEB: Your Partner in Automation & Control

If you’re looking for a specific servo control or automation solution for your project, then contact a KEB application engineer today! Our experts are here to discuss the unique needs of your application—and connect you with the right support to see it through. From resources to world-class products and services, we’ve got you covered.

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