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‘How does an actuator work’ is a question we hear fairly often here at Actuonix, and we understand why. Linear motion can involve some complex concepts and hardware and sometimes can be a little challenging to wrap your head around. Keep reading and we will help you better understand the actuator definition in terms of components and uses.
What is an Actuator and How Does it Work?
Simply put, an actuator is a device that converts energy into motion. For electric linear actuators, this means converting the rotary motion of an electric motor into linear motion. Electric motors are not new technology, and have been around for nearly 200 years! For much of that time, converting the rotary motion of an electric motor to linear motion involved complex setups utilizing gears, belts, pulleys and other hardware. It was complex and expensive.
The fundamental principle of an electric linear actuator is the conversion of electromagnetic energy into mechanical force via a lead screw mechanism. By utilizing an input signal to trigger a motor, the device provides controlled, repeatable movement in a straight line.
While all actuators convert energy to motion, they are classified by their power source. Electric actuators use AC or DC electricity, Pneumatic actuators use compressed air, and Hydraulic actuators use pressurized liquid. For micro-motion, electric is the industry standard due to its precision and clean operation.
Modern linear actuators save engineers and product designers significant time and hassle by providing a pre-engineered, self-contained motion solution. Instead of manually designing a linear stage from a collection of individual motors, gears, and rods which requires precise alignment and extensive testing, an actuator allows for plug and play integration. This consolidation reduces design overhead and allows for a much smaller mechanical footprint in the final product.
When we talk about linear actuators, we often discuss the trade-off between force and speed. However, to fully appreciate this, it’s useful to understand how a linear actuator works, and what is going on inside the actuator during operation.
How Does an Actuator Work?
An electric linear actuator is a mechanical device that converts an input signal into physical motion or force. It achieves this by utilizing various mechanisms, such as motors, gears, rods and screws, to convert the rotary motion of a standard electric motor into smooth linear motion.
| Actuator Type | Main Advantage | Best Use Case |
|---|---|---|
| Electric | Precise control & simple wiring | Robotics, Medical, Aerospace |
| Pneumatic | High speed & low cost | Packaging & Assembly lines |
| Hydraulic | Extreme force capability | Heavy Construction & Mining |
Below, we will dive into each aspect of how an electric actuator works including the internal components, control types and aspects that affect actuator performance.
What’s inside an electric linear actuator? Let’s have a look. Most electric linear actuators operate in roughly the same way.
Linear Actuator Components
An actuator consists of several key components that work together to convert rotational motion into linear motion. Here are the components that you will find in a typical electric linear actuator:
Electric Motor
The motor generates the rotational force that drives the actuator. This is typically through a gearbox assembly. Most micro actuators utilize brushed DC motors for their reliable performance and simple control requirements.
Gearbox
The gearbox lives between the motor and the lead screw. The gearbox is responsible for determining the speed and force of the actuator. Different gearing setups result in different force/speed combinations. A higher gear ratio increases torque (force) but results in a slower linear speed.
Lead Screw
The lead screw is where rotational motion is converted to linear motion. In a typical actuator, the lead screw spins with the output shaft of the gearbox. A captive block or nut is mounted on the lead screw and moves along the length of the screw as it spins. The thread pitch of this screw also plays a role in determining the final speed and load capacity.
Rod
Rod actuators have a rod assembly that is mounted to the nut and moves up and down the lead screw with the nut.
External housing
Most actuators are encased by an external housing that keeps the components all in their proper place as well as protects them from the elements.
Other components
You may find other electronics within an actuator. This can vary a lot from model to model but some common components are end limit switches, potentiometers, and circuitry to support other functions. Potentiometers provide position feedback, allowing the user to know exactly where the actuator is in its stroke at any given time.
Key Performance Factors: Choosing the Right Actuator
Understanding the internal components is only half the battle. To successfully integrate an actuator into your project, you must balance three critical performance factors:
1. Force vs. Speed
This is the most common trade-off in linear motion. Because power is finite, an actuator with a high gear ratio will offer significant force (pushing power) but will move at a slower speed. Conversely, low-ratio gears offer high speed but lower force capacity.
2. Stroke Length
The stroke length is the total distance the actuator can extend. In micro-motion, precision is key—ensure your design accounts for the "retracted length" (the total size of the housing) as well as the extension distance.
3. Control & Feedback
Do you need simple end-to-end movement, or precise positioning? Linear Servos use internal feedback (potentiometers) to allow for complex, proportional control, while basic actuators are ideal for simple on/off tasks.
Selecting the ideal device involves more than just matching a power source to a motor. It requires a holistic look at your environment, the mechanical stress the device will endure, and the level of precision your control system requires. By prioritizing these three variables early in the design phase, you ensure a longer lifespan for the actuator and better overall reliability for your application.
Common Questions About Actuators
How to adjust an actuator stroke?
Most linear actuators do not have adjustable limit switches. That said, you can adjust the stroke length in a variety of ways depending on your specific actuator. Some options include external limit switches, software limits in controller code and custom LAC board settings.
What is the duty cycle of a linear actuator?
This varies by device. Duty cycle is the ratio of 'on-time' to 'rest-time,' usually expressed as a percentage. For example, a 20% duty cycle means that for every 2 minutes of operation, the actuator requires 8 minutes of rest to prevent overheating. Consult the manufacturer of your specific actuator for information on duty cycle.
What happens if you run an actuator to a hard stop?
Running to a hard stop is one of the fastest ways to destroy a linear actuator. This can cause motor failure, mechanical stress, overheating, inaccuracy and will reduce the life of the device. Always use limit switches or current sensing to avoid hard stalls.
What is the difference between a linear actuator and a linear servo?
A standard linear actuator typically moves from one end of its stroke to the other. A linear servo includes internal feedback and a control board that allows for precise, proportional positioning anywhere along the stroke length using a standard RC or PWM signal.
Should I use a 6V or 12V linear actuator?
Ultimately this comes down to how you're planning to control the actuator. If you're integrating it into a 6V system, then it makes sense to choose a 6V actuator. Additionally, most of our linear servos operate at 6V and are a good fit for RC, Arduino and other PLC applications.
Browse Actuators From Actuonix Today
This article's breakdown of “What is an actuator” should help you identify exactly what you need. View our collection of actuators by model or industry today. As a leading manufacturer and innovator in the micro motion marketplace, Actuonix services companies big and small in a number of industries including aerospace, medical, robotics, and more. Get in touch with us today to submit an order or to submit an inquiry.
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