What Are Different Types of Actuators?

Whether you’re a machine expert or someone who is still gaining knowledge about motor device parts, you are most likely aware of the actuator and its significance.

Actuators serve the general purpose of controlling movements within machines. However, there are various kinds of actuators that produce varying motions and use different power sources. Distinguishing the differences between these motion-controlling devices will help you troubleshoot parts or refine the processes within your machine.

Let’s take a look at the different types of actuators and their functions, as well as some tips for keeping them working at peak performance.

What is an Actuator?

An actuator is a machine part that initiates movements by receiving feedback from a control signal. Once it has power, the actuator creates specific motions depending on the purpose of the machine.

What Are Some Devices with Actuators?

Machines and systems have featured actuators since their popularization back in World War II. The most well-known examples of actuators include:

  • Electric motors: Any part of a piece of equipment or appliance that translates electrical energy into motion, such as those found in ventilation fans, blenders, or refrigerators, contains at least one actuator. Electric cars also use actuators.

  • Stepper motors: These actuators are best known for receiving digital pulses and converting them into mechanical motion. Stepper motors are often seen in robots, smart tools, or automated cutting equipment.

  • Hydraulic cylinders: These are linear-motion devices that operate using a tube, piston, and rod. Many vehicles operate using hydraulic motion, such as bulldozers, backhoes, or excavators.

What Are Some Different Types of Actuators?

Actuators can be classified by the motion they produce and the power source they use.

Motion

Actuators can create two main types of motion: linear and rotary. 

Linear Actuators

Implied by their name, linear actuators are devices that produce movement within a straight path. They can either be mechanical or electrical and are mostly seen in hydraulic or pneumatic devices. Any machine, equipment, or gadget that requires some form of straight motion typically has a linear actuator.

In a simple linear actuator, there is a nut, cover, and a sliding tube. The sliding tube provides the space for the motion, whereas the nut and cover provide the interlocking movement that keeps the actuator in a straight path. Other complex linear actuators will have additional parts, but the system mentioned above is the foundation for straight movement.

Rotary Actuators

In contrast to linear actuators, rotary actuators create a circular motion. From the term “rotary,” most machines use these rotating parts to complete a turning movement. They are often used in conjunction with a linear actuator if a machine requires moving forward, backward, up, or down.

Many rotary actuators are electrically powered, but some are powered using a hydraulic or pneumatic system. You can find rotary actuators in windshield wipers, electric fans, or manufacturing machines that transport goods from one area to another.

Source of Energy

To further distinguish different types of actuators, we can also sort them according to the power source or system they use to move. Below are the most common actuators according to energy source:

Hydraulic Actuators

Hydraulic actuators operate by the use of a fluid-filled cylinder with a piston suspended at the center. Commonly, hydraulic actuators produce linear movements, and a spring is attached to one end as a part of the return motion. These actuators are widely seen in exercise equipment such as steppers or car transport carriers.

Pneumatic Actuators

Pneumatic actuators are one of the most reliable options for machine motion. They use pressurized gases to create mechanical movement. Many companies prefer pneumatic-powered actuators because they can make very precise motions, especially when starting and stopping a machine.

Examples of equipment that uses pneumatic actuators include:

  • Bus brakes
  • Exercise machines
  • Vane motors
  • Pressure sensors
  • Pneumatic mailing systems

Electric Actuators

Electrical actuators, as you may have guessed, require electricity to work. Well-known examples include electric cars, manufacturing machinery, and robotics equipment. Similar to pneumatic actuators, they also create precise motion as the flow of electrical power is constant.

The different types of electrical actuators include:

  • Electromechanical actuators: These actuators convert electric signals into rotary or linear movements and may even be capable of a combination of both.

  • Electrohydraulic actuators: This type of actuator is also powered electrically but gives movement to a hydraulic accumulator. The accumulator then provides the force for movement, usually seen in heavy industrial equipment.

Thermal and Magnetic Actuators

Thermal and magnetic actuators usually consist of shape memory alloys that can be heated to produce movement. The motion of thermal or magnetic actuators often comes from the Joule effect, but it can also occur when a coil is placed in a static magnetic field. The magnetic field causes constant motion called the Laplace-Lorentz force. Most thermal and magnetic actuators can produce a wide and powerful range of motion while remaining lightweight.

Mechanical Actuators

Some actuators are mostly mechanical, such as pulleys or rack and pinion systems. Another mechanical force is applied, such as pulling or pushing, and the actuator will leverage that single movement to produce the desired results. For instance, turning a single gear on a set of rack and pinions can mobilize an object from point A to point B. The tugging movement applied on the pulley can bring the other side upwards or towards the desired location.

Supercoiled Polymer Actuators

Supercoiled polymer actuators are a relatively new addition to the different types of actuators. They are used in robotics and prosthetic limbs as they can replicate the motion of human muscle via a coil that contracts and expands when heated or cooled.

How to Select the Right Actuator

Understanding the different types of actuators is a crucial step in making the best selection for your equipment. Since each kind has its unique purpose and energy requirements, we’ll go over factors that will help you arrive at the best decision.

Power Source Availability

The first thing you have to consider is the compatibility of your power source. If you own an industrial site with an electrical source, perhaps the best choice—and the option with the most selections—would be electric actuators. If there are no electrical sources in the area, or you want a piece of fully functional equipment without electricity, you can opt for pneumatic or hydraulic types.

Required Movement

Another important factor when choosing an actuator is the range of movement that you need for your equipment. Is it linear, rotary, or an integration of both? Custom-made actuators can combine or chronologically create these motions to help you concretize the final equipment.

Precision

Some actuators are more precise than others. For example, air brakes are created through pneumatic actuators because air pressure is known to be efficient in the start and stop movements. Other actuators have a larger margin of movement variations, such as those operated through hydraulics. 

Any industry that requires a high level of precision for safety and success of operation should consider actuator types that have specific movements.

Safety and Environmental Concerns

Safety is another factor to consider when choosing an actuator for your equipment. Electrical or thermal actuators should be used with caution in areas with extreme temperatures or conducting hazards. For example, operating electrical actuators close to a water body without sealing or other safety measures may create an occupational hazard.

If your company is also committed to a reduced carbon footprint, you’ll need to note each actuators’ environmental impact. Typically, electrical actuators have little to no carbon footprint.

Official Guidelines

There are also specific guidelines to follow for industrial actuators in certain areas. For example, locations with a high presence of combustible gases should adhere to the requirements imposed by the National Electrical Manufacturers Association (NEMA).

Maintaining Your Actuator

All equipment requires maintenance. Maintaining your actuators will help prevent major shutdowns, hazards, or loss of productivity. Here are some general tips to keep your actuators in top shape.

  • Regular inspection: Performing routine visual equipment checks will identify early signs of actuator issues. A mechanic with a keen eye is necessary to inspect for wear and tear.

  • Replenish and replace: Hydraulic actuators sometimes need cylinder fluid replenishment. Always double-check for leaks and signs of low hydraulic fluid levels. Replace loose or damaged nuts, bolts, coils, or screws in your actuator parts as well.

  • Measure performance data: In some cases, actuators won’t show external signs of a problem, but you can trace issues through performance. Automated graphs and output computation may be necessary if you want to catch deeper issues.

Need an Actuator? We Can Help

Whether you’ve already made a decision and need an actuator or are still undecided and need a bit more information about the different types of actuators, our team is standing by to help. Creative Motion Control is home to a skilled group of engineers, researchers, and technicians committed to providing the best actuators on the market. Contact us today at (425) 800-8045 to discuss your needs or request a quote.

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