Choosing the Right Actuator Type for Your Application

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Sometimes the choice between the three main actuator types – electric, pneumatic and hydraulic – is a no brainer. For example, if you need heavy-duty motion, a hydraulic actuator would be the obvious choice, a potentially explosive environment necessitates the use of a pneumatic actuator and a sterile operation would demand an electric actuator. But beyond these and other obvious situations, choosing the best type of actuator for a motion control application can be tricky.

And, while any type of actuator must provide precise positioning, start and stop without delay and perform reliably in the application, considerations beyond these basic requirements must be examined during the selection process. So, this blog will discuss the operating principles, the pros and cons of electric, pneumatic and hydraulic actuators and key specifications to help make your selection process easier.

What is an Actuator?

Before getting into the selection process and the specifics of each actuator type, it’s important to understand the function of actuators in motion control applications. As mechanical components that convert energy into lifting, ejecting, pressing, clamping and other motions, actuators are found in almost every machine and device that features moving parts and are used in industrial applications to activate equipment such as pumps and valves.

Actuators are categorized by both the type of motion they produce and the form of energy used to create that motion. Linear actuators provide straight-line motion and rotary actuators provide circular motion. Further, hydraulic actuators depend on hydraulic fluid to create and control motion; pneumatic actuators use pressurized air to activate and manage motion; and electric actuators generate motion via electricity.

Electric Actuators: Advantages and Disadvantages

Electric actuators receive electrical currents that energize an electric motor, which in turn generates a force that moves the desired component. Electric actuators usually include feedback devices and self diagnostics, which make them more complex, but also very precise, repeatable and reliable. Because they offer clean, electronic control, electric actuators provide many performance advantages in applications such as electronic and medical devices and clean room or sanitary applications.

Electric Actuator Advantages:

• Precision control and performance
• Very accurate positioning and velocity control
• Excellent response times
• High speeds
• Environmentally and clean-room friendly as they do not require the use of hydraulic fluids or compressed air
• Reduced operating costs as they are very energy efficient and do not require fluids or compressed air to operate
• Small in size

Disadvantages of Electric Actuators

• Not as much strength and power as other actuator types
• Complex designs
• Higher upfront costs

Pneumatic Actuators: Advantages and Disadvantages

Pneumatic actuators use compressed air as the energy source and convert it into mechanical energy to create force in motion control applications. They are known for high speeds and are ideal in applications such as air-operated tools and industrial equipment. They are a convenient choice in industrial settings as most are already equipped with an air compressor and are safe to use in locations where fire or explosion hazards exist.

Disadvantages of Pneumatic Actuators

• Can be inefficient due to pressure losses associated with the use of compressed air
• May be slower to respond if air pressure is inadequate
• Air can become contaminated with oils or moisture found in the pneumatic system
• Can be costly to operate if the compressed air system is not optimized and efficient

Advantages of Pneumatic Actuators

• Accurate and repeatable motion profile
• Can be safely used in explosive environments
• Minimal maintenance and reliable operation
• Low upfront cost
• Simplicity of design
• Easy installation

Hydraulic Actuators: Advantages and Disadvantages

Hydraulic actuators rely on hydraulic fluid that is supplied by a pump to create and control movement. Adding pressure to the fluid will generate force while reducing pressure will lessen the force. Hydraulic actuators can provide significant force and are a self-contained system, making them a favorite in heavy-duty applications such as construction and agricultural vehicles and equipment.

Disadvantages of Hydraulic Actuators

• Leakage of hydraulic fluids may pose an environmental hazard and prevent use in applications where contamination of product is prohibited
• Slower speeds
• Not as precise, accurate or repeatable as other actuator types
• Can become inefficient and inaccurate if there are fluid leaks
• Higher upfront costs due to companion components such as pumps and fluid reservoirs
• Higher lifecycle costs for fluid replacement and maintenance
• Not safe for use in applications where fire is a potential hazard as hydraulic fluid is flammable

Advantages of Hydraulic Actuators

• Provide extreme force, strength and power
• Easy to control
• Dependable and reliable operation
• Long service life
• Self-contained and portable as they do not require a pneumatic system or electrical input to operate

Other Selection Criteria

All actuator types exhibit both advantages and disadvantages and often these strengths and weaknesses will dictate whether an electric, pneumatic or hydraulic actuator is the best choice based on the application needs and/or the working environment. In all cases, it is important to consider the requirements of the application to ensure that the selected device will adequately fulfill the needs of the motion control profile, so consider the following during the selection process:

• What type of motion is needed, linear or circular?
• How much force is required?
• What stroke length is needed?
• Positioning accuracy and repeatability needed?
• How fast does it need to move and respond?
• What is the duty cycle (how often the actuator will operate)?
• What is the device footprint?
• Are there special considerations such as use in outdoor environments, potential for fire or explosion or contamination concerns?

Once you have a clear understanding of the needs of the application, it is easier to choose the right actuator for the job. Reputable suppliers like JHFOSTER can provide additional assistance during the selection process to ensure that you purchase an actuator that is well suited to the application and of the highest quality for the most reliable, efficient and cost-effective operation.

If you want to learn more, please visit our website advantages of pneumatic systems.

By Duff-Norton | Dec 20, 2022

When buying a linear actuator, it’s important to choose a product that will fit best with your application and specific demands. Whether you want a high load capacity, a longer duty cycle or something that requires very little maintenance, you’ll need to research each ‘type’ of actuator thoroughly.

In this post, we’ll discuss the advantages and disadvantages of two of the most popular types of linear actuators – hydraulic and electric – to help you find the perfect device for the job.

What is a hydraulic linear actuator?

Hydraulic linear actuators use fluid and pressure to provide movement and apply force. They have a high-power density which enable small package sizes that provide a high load/thrust capacity from a relatively small cylinder. However, system design and cost must also be considered because of the need for auxiliary components to provide pressure, such as motors, pumps, filtration, hoses, and couplings. Pressurized systems also tend to have higher long-term maintenance costs due to the need to contain the integrity of the system for seals, leaks, or other issues that may arise. 

These actuators are powered by pumps of incompressible oil. The pressure that the fluid creates moves the cylinders and, in turn, helps move your application.

Pros

• Load capacity. Unlike electric linear actuators, hydraulic actuators are suited to high-force applications and are customizable to almost any weight. They are also the most powerful actuator on the market and are suitable to work under heavy pressures.
• Convenience. The external pumps and motors for this type of actuator can be placed a reasonable distance away from the application without affecting the power supply.
• Constant pressure. Due to the incompressibility of liquid, a hydraulic actuator can hold constant force without the pump having to supply more pressure.

Cons

• Leakages. These actuators require expensive plumbing, maintenance and continuous checks. Due to the nature of the product, the likelihood of oil leakages is high. Additionally, high temperature environments can cause damage to the product if not monitored diligently.
• Components. Hydraulic linear actuators are not contained and require numerous external components. If you’re looking for a small device, these may not be the best for your needs.
• Speed. These devices are hard to control accurately and may suffer from ‘stick slip’. Put simply, this is where a linear actuator jolts and jerks in the transition between being still and moving.
• Cost. Although the cost of the initial components is relatively low, the cost of installation and maintenance can be pricey. Unfortunately, if you want your hydraulic actuator to run smoothly, the cost of regular maintenance is a necessary price to pay.

What is an electric linear actuator?

Electric linear actuators, also known as electromechanical actuators, convert torque to linear displacement (travel and force). They are mechanical components that use electric motors coupled to machine or ball screws and gear sets to provide mechanical advantage. There are many combinations available to supply a wide range of speed and load requirements. These actuators are available with many standard features and numerous options, such as limit switches, position feedback, and more to ensure they can fit a wide range of application needs. While electric linear actuators may have a higher upfront cost and require a larger footprint to install (since they include the motor and mounting), they are easier to maintain and have lower long-term maintenance costs. When sized properly, they are durable and ensure long product life.

Unlike the hydraulic variant, these linear actuators are powered exclusively by motors. The motor powers the lead screw, which is fitted with a nut that runs up and down the thread. This converts the rotary motion into linear movement.

Pros

• Precision and speed. This actuator offers repeatable capabilities with easy, automatic operation controls. The speed of the device is also easily controlled and smooth.
• Less maintenance. As there’s no risk of fluid leakages, there’s very little requirement for regular maintenance. This, of course, reduces costs and increases productivity for both the application and your team.
• Quick installation. Setting up electric actuators only requires simple wiring, meaning you can install your device quickly and cheaply.
• Load holding and safety. Most electric actuators contain acme screw units (or fail-safe brakes) which are self-locking in the event of a power failure.
• Contained. These actuators don’t require external pumps or motors and are therefore much smaller and take up less space.

Cons

• Unsuitable environments. Although these actuators will perform well in most environments, installation in hazardous or flammable areas requires the use of equipment rated for these conditions.  Only actuators specifically created for use in environments where flammable or explosive gases or particulates are present should be used in these applications. This is necessary in order to prevent injury or damage.
• Overheating. If left running for too long, or over the specified duty cycle, electric actuators may overheat and reduce efficiency.
• Cost. The initial cost of purchasing an electric actuator is high. However, the running and maintenance costs after this are significantly lower than that of a hydraulic actuator

Why would you use an electric linear actuator?

Electric linear actuators allow for precise motion control. While fluid (also known as hydraulic) valves have improved over time, they are not as precise as a motor. Also, if your application has specific needs, such as harsh environment (washdown and sealing options) or requires explosion proof equipment, electric linear actuators are available with options that meet these classification requirements.

Which is best for you?

Although both variations create a reliable and powerful linear motion for your application, each have their own advantages and disadvantages. So when making your decision, pick the right actuator for your application, specifications and environment.

At the end of the day, making the wrong choice can only cause more hassle in the future, so if you need more guidance to inform your decision, get in touch with a professional who can advise you further.

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