Why are Electric Actuators so Precise and Repeatable?

Electric actuators continue to grow in popularity in the motion industry, but what makes them move so precise and repeatable? At the very basic level, electric actuators utilize motors that generate rotary motion and a belt or screw to convert that rotation to linear motion, all while employing a variety of motion control devices to dictate that motion.

Electric motors utilize electrical currents to generate either linear or rotary mechanical motion, which in turn moves a ballscrew, toothbelt, or similar motion transfer mechanism. There are two main differentiators in electric motors: AC vs DC current, and stepper vs servo style.

As the names suggest, AC motors utilize AC current, while DC motors utilize DC current. AC motors require lower startup power demands and offer the flexibility of controlling both speed and torque at different stages of use. Comparatively, DC motors are simpler to install, easier to maintain and produce greater startup power and torque. AC motors tend to be more powerful than DC motors because they use a more powerful current. However, DC motors are typically more efficient.    

Stepper motors create incremental motion that simulates continuous motion using internal poles that energize in sequence. They often operate open-loop (require no feedback) and can create immense torques at low to no speeds. Stepper motors are relatively easy to deploy and are economical for applications that require extremely smooth, consistent motion and don’t require high speeds at high torque.

Servo motors provide an excellent alternative to stepper motors for high speed, high accuracy applications. They can run at thousands of RPMs; when paired with a gearbox, a servo motor can provide extreme torque for the relative speed. Due to their complex constructions, servo motors must be operated closed-loop (position feedback), necessitating the use of a controller/drive to direct the motion.

Key Advantages of Electric Actuators

Step motors:

  • Lower total cost of ownership when compared to servo motors
  • Easier to setup and use than servo motors
  • Constant holding torque even at zero speed
  • Higher torque output than servo motors at lower speeds

Servo motors:

  • Highly efficient – servo motors use only the energy required to perform the motion
  • Constant torque output even at higher speeds
  • Very quiet and smooth operation – less audible noise
  • Built-in positioning correction provides greater precision

Want to find out if electric motion is right for your application? Speak to one of our experts today to learn more!