For handling extensive or heavy loads in excess of 3,000 pounds, it makes sense for engineers to implement hydraulic cylinders. They use electricity to create motion, which in turn completes a specific task. They&#;re often used in motors, pumps, oil filters, relief valves, and other types of valves. Industries like aeronautics, manufacturing, and construction rely on the technology in heavy machinery and mission-critical systems.
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But hydraulic cylinders are also bulky, with many complex components, so they can be very difficult to implement when spaces or designs are tight. A sound alternative is an electro-hydraulic actuator.
Electro-hydraulic actuators aren&#;t all that different in size from hydraulic cylinders. However, they are designed differently, with remarkably unique internal compositions. A hydraulic cylinder is often densely packed with components and parts, many of which can develop leaks or issues over time &#; primarily due to constant vibrations and movements.
Electro-hydraulic actuators, on the other hand, are self-contained, with unique properties that make them more suitable in various applications. They are low-maintenance, relatively durable, and provide plenty of power.
To understand when and where an electro-hydraulic actuator makes more sense for a project or system, it&#;s best to consider the pros and cons of their use.
The Pros of Electro-Hydraulic Actuators
Overall, when compared to hydraulic cylinders, electro-hydraulic actuators have a significant advantage thanks to higher power density, low maintenance requirements, location and usage versatility, cleanliness, and general cost. What&#;s more, because they can handle up to a 4,800-pound load, they can be used in instances where traditional hydraulics cannot.
Engineers have a lot more freedom and design flexibility when it comes to implementing electro-hydraulic actuators, meaning they can create more efficient and nuanced systems. The self-contained power also means they don&#;t need to be placed near other components or in a specific configuration. They do not rely on anything else.
They offer much higher precision and are scalable for any purpose or force requirement even well above traditional hydraulics. What&#;s more, they can be programmed, networked, and diagnosed quickly &#; especially since they require very little maintenance. Engineers and system operators gain complete control over the resulting hardware with the option to choose custom speeds, stroke lengths, or applied forces.
They are also much much quieter than hydraulic actuators, so they can be used in unique instances where noisy components may not be ideal. If you&#;ve ever been around a hydraulic press, you know just how loud traditional systems can get. Electric alternatives are quiet, efficient, powerful, and make a lot more sense in certain instances, especially when engineers need to be creative.
The Cons of Electro-Hydraulic Actuators
At one point in time, electric actuators were not commonly used because their design introduced many problems. They were weak, unreliable, and presented similar challenges. That&#;s no longer the case. In fact, today, they&#;re better and more powerful than many traditional hydraulics. They&#;ve come a long way, and the technology offers a more influential and dependable solution.
That&#;s not to say they are perfect. The biggest disadvantage of electro-hydraulic actuators is the upfront cost, especially when multiple units need to be deployed or installed. They are more expensive initially than traditional hydraulics or pneumatics. They&#;re also not safe for all conditions. For example, in flammable areas or where extremely high heat is created, it&#;s dangerous to use an electro-hydraulic actuator over a traditional system.
Finally, while the benefits of fluidless systems mean very little maintenance, and eliminate the need to inspect for leaks or similar problems, when something does go wrong, it&#;s necessary to have a specialist in place. The good news is that failures or malfunctions are rare with electro-hydraulic actuators. But they do happen. When something does go wrong, the likelihood of having an expert on your team is small, unless you seek out professionals with direct experience.
The Verdict
Despite the benefits and the increase in power density, it&#;s important to note that electro-hydraulic actuators are not ideal for every situation. The upfront cost, especially for more units, can be quite an obstacle for smaller operations. The usage cost is justified over time, but the upfront cost can be too great depending on how many units are necessary and what&#;s required.
As mentioned, they&#;re not ideal for use in hazardous conditions either, namely around flammable components and emissions. Extreme heat or cold can present unique challenges as well, so it&#;s best to refrain from using electro-hydraulic actuators in these rare circumstances.
However, there is something to be said about the self-contained design of electro-hydraulic actuators. Harsh conditions &#; which are not necessarily the same as extreme heat or flammable conditions &#; are still a major possibility for electric actuators because they do not suffer jamming problems, do not experience leaks and are relatively protected overall since they do not rely on external components or connectivity.
What&#;s most promising is that they can be continually improved over time to be much more efficient than comparable and traditional systems. That includes gains in noise suppression, fewer emissions, improved durability, and better power output, depending on the surrounding conditions and application. One could say it&#;s a relatively young technology, at least in hydraulics, that will continue to see major improvements in the years ahead.
Should You Choose Electro-Hydraulic Actuators?
While electro-hydraulic actuators certainly come with their share of benefits, all three hydraulic technologies &#; hydraulic linear, pneumatic, and electric &#; have their place in industrial settings. Unfortunately, there&#;s no one-size-fits-all system that&#;s viable for every single application. It&#;s best to take time to assess which form of hydraulics is right for the project and task and then implement accordingly.
Industry veterans may know that, somewhere along the line, electric actuators were just not commercially or economically viable, especially since they were weaker than some of the other solutions. That&#;s no longer the case, and the technology has not just advanced considerably but also now continues to grow more capable and prevalent every day. We&#;re starting to see its use in many industries, like aviation, manufacturing, construction, and others.
The need for actuators has grown exponentially. Nearly everywhere you look, you can see one of the three types of actuator motion systems at work in an endless variety of applications. There are many misconceptions involving pneumatic, hydraulic, and electric actuators. While some of these ideas may be true, many of the notions we have associated with these motion components are outdated and need to be revisited. Whereas you may think that your application&#;s need for actuation rests on one specific type of actuator, technological advances have allowed us to reexamine the specifics of each, which could mean more than one option for your project. It is essential first to identify the primary way each type of actuator completes its job.
Pneumatic linear actuators are composed of a simple piston inside of a hollow cylinder. A manual pump or external compressor will move the piston within the cylinder housing. As this pressure increases, the cylinder will move along the piston's axis, creating the linear force needed. It returns to its original retracted length by either a spring-back force or providing fluid to the piston's opposite side.
Hydraulic linear actuators are quite similar to pneumatic actuators, except for the use of an incompressible liquid supplied by a pump instead of pressurized air moving the cylinder in a linear motion. This hydraulic actuator comprises two essential parts: a control device, such as variable throttles (nozzles with slide gates or paired slide valves with an initial axial gap), and an actuation component, such as a piston or controlling valve slide.
Electric linear actuators &#; also called an electric cylinder, an electric cylinder actuator, or an electric lift cylinder &#; take the rotational force of a motor (electrical energy) and convert it into linear movement (torque). By rotating the actuator&#;s screw via the motor, the nut will move in a lineup and down, creating the load's push/pull effect.
Each type of these actuators is essential to their appropriate application, but as mentioned before, significant advances in the manufacturing world have allowed for these motion devices to be interchangeable. Each has its advantages and disadvantages, so be sure to weigh the options before deciding on the right actuator for your project.
Characteristics
Pneumatic
Hydraulic
Electric
Complexity
Simple system composition
Moderately complex system composition
Control systems and motion components can work together in multiple complex configurations
Peak Power
High
Very high
High
Control
Simple valves
User must
Flexibility of motion control capabilities with electronic controller
Position
Accuracy
Very difficult to achieve position accuracy
Mid-stroke positioning requires additional components and user support
Positioning capabilities and velocity control allow for synchronization
Speed
Very high
Moderate
Moderate
Load Ratings
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High
Very high
Can be high depending on the speed and positioning desired
Lifetime
Moderate
Long
Long
Acceleration
Very high
Very high
Moderate
Shock Loads
Able to handle shock loads
Explosion-proof, shock-proof, and spark-proof
Limited ability to handle shock loads
Environmental
High noise levels
Hydraulic fluid leaks and disposal
Minimal
Utilities
Compressor. power, pipes
Pump, power, pipes
Power only option
Efficiency
Low
Low
High
Reliability
Excellent
Good
Good
Maintenance
High user-maintenance
High user-maintenance
Little to no maintenance
Purchase
Cost
Low
High
High
Operating
Cost
Moderate
High
Low
Maintenance
Cost
Low
High
Low
Although advances in the manufacturing world have come quite a long way, there are still specific applications in which electric lift cylinders cannot compete with the load ratings, force, or speed necessary. Some environments are unsuitable for electric actuation and have a maximum velocity that cannot be exceeded. Although it is rare, electric actuators can overheat if there are extreme changes in the duty cycle or used outside of their warranty.
Shock loads on an electromechanical actuator affect its lead screw or bearing, resulting in the possibility of it affecting the entire system&#;s performance. Some electric actuators can have difficulty holding a locked position or have issues with backlash, usually dependent on the screw pitch. Although the electric motion system's initial cost may be more expensive than other actuators, the whole operation's increased efficiency coupled with the little to no maintenance required over its life span makes the total cost lower than different types of actuators.
Each actuator type exhibits both good and bad characteristics that one must weigh when determining their application project's best solution. By deciding what features are non-negotiable from the start, you will begin to rule out particular actuators based on these needs. Suppose it comes down to two specific actuators, both able to do the necessary job efficiently. In that case, you may want to consider the entire cost of the system: this includes the initial investment, maintenance, and repair fees, as well as the cost of potential risks you could take with each motion component system.
It is also essential to choose the right company to purchase your product for optimum results. TiMOTION is an industry-leading provider of electric linear actuators, capitalizing on a global team specializing in innovative solutions to manufacture the best products for industrial, furniture, medical, and ergo markets worldwide. We understand that the right technology can solve nearly any problem and that drop-in replacement, customizable electric linear actuators are used increasingly in applications that have outgrown pneumatics and hydraulics. TiMOTION strives to provide the highest quality, customizable components at competitive pricing. For more information, visit us online today at TiMOTION.
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