Author: Kyle Sendatch, Mechanical Engineer
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Within industry groups as varied as manufacturing, transportation and national defense, you&#;re sure to find actuators filling an important role. Actuators are critical in controlling and facilitating practically every mechanized process.
As such, actuators play a prominent part in the world&#;s economy. Market evaluation statistics suggest that the actuator and valve sector will generate over $127 billion by . The actuator business is currently expanding at a compound annual growth rate of 5.23%. This economic activity involves the three main actuator types &#; hydraulic, pneumatic and electric.
Actuators are mechanical devices that convert energy into motion. This involves a control command that signals a change in a physical system which then generates force to accomplish a task. The commanding signal can be human-operated or automatically controlled while the energy source varies.
The primary function of actuators is to control machines and allow parts to move. This motion can be any one of hundreds of operations such as lifting, clamping, blocking and ejecting. Typically, actuators are key parts in industrial and manufacturing operations where they activate valves, pumps, motors and switches.
Actuators usually control and direct mechanized motion. Movements can be linear, rotary or oscillatory. In other terms, that motion can be in one direction, circular or back and forth in regular intervals. No matter what end motion a mechanized system desires, it would impossible to achieve without actuator assistance.
Practically every industry uses actuators in some manner. Operations in oil and gas processing, aviation and aerospace, military and defense, marine, mining, forestry and road building require actuators. Actuators are also used in manufacturing equipment like presses, cranes, drill rigs, coal crushers, man lifts, missile launchers and material handling equipment. Name an industry or service, and you&#;ll see them using actuators somewhere down the line.
As noted above, there are three different actuator types &#; hydraulic, pneumatic and electric. We will get into more detail about each style and its advantages and disadvantages below.
Actuators classify first by the type of motion they produce. While rotary actuators generate rotation, linear actuators move in a straight path. Either type can also take the designation of oscillating if the movement cycles regularly.
Actuator types are next characterized by what energy form the actuator employs to convert the source from a potential state into physical motion. Potential energy is stored energy with the ability to do work. Kinetic energy is the energy of motion. The most common energy sources are compressed fluids, compressed gas and electricity.
Hydraulic actuators operate with compressed fluid and control movement by managing the amount of fluid inside. Adding fluid increases pressure while reducing it lessens the force. These actuators are ideal for applications that need more significant power, but you can also commonly find them in products like exercise equipment.
The primary advantage of pneumatic systems is that they run on compressed air or gas instead of fluid. As a result, they are involatile and require no electricity to perform. Pneumatic actuators are versatile and affordable, making them popular for braking systems and pressure sensors.
The function of an electric actuator is to generate mechanical power from electricity input. Since the power source is consistent and continuous, these actuator types offer easy maintenance and are ideal for high-precision work. Electric actuators are common in manufacturing, robotics and electric vehicles.
You&#;ll find a lot of debate over actuators, but which actuator type is the best depends on your application. In some situations, electric and pneumatic actuators are the best choice. However, in many applications today, hydraulic actuators give you superior performance. Read on to discover more about the benefits, drawbacks and popular applications of each actuator type.
Hydraulic actuators remain the most popular energy conversion systems. They are common in heavy-duty work like large construction machinery, marine propulsion and cargo handling, military weapons and transportation systems and overall jobs where brute power rules.
Hydraulic actuators work on fluid compression and convert that pressure into motion under controlled circumstances. In almost all hydraulic systems, that fluid is some form of oil. Because oil is very difficult to compress, it easily transfers large amounts of energy by volume.
Pressurized hydraulic oil is used in cylinders, which are tubes containing rams. Hydraulic actuators use pressurized fluid energy to drive the ram and operate the device or machine that the actuator serves. Pressures used in a hydraulic actuator ranges between 1,000 to 5,000 pounds per square inch (psi). Large actuators can exceed 10,000 psi for specialized applications.
Hydraulic actuators provide the greatest overall force and power density you can get with any actuator design. They&#;re relatively simple mechanisms with two main parts &#; a control device like a throttle and an actuation component such as a piston, slide or valve. Here are some pros and cons of hydraulic actuators.
If it&#;s heavy-duty work you require, then there are far more pros to investing in hydraulic actuators than relying on air or electric power. Your return on investment is strength, efficiency and convenience among these other points:
Although hydraulically controlled systems have considerable advantages over their rivals, they do have a few drawbacks. There are some applications where hydraulic power may not be compatible, in settings where there is any chance of contaminating product. Here are a few more cons you should know about if you&#;re considering hydraulic actuators.
Pneumatic actuators are popular choices in many industries. Compressed gas has considerable energy to be harnessed, and most pneumatic actuator systems just capture air. Fortunately, there&#;s a plentiful air supply in almost all applications where you&#;d consider using an actuator.
Contact us to discuss your requirements of Electro Pneumatic Valve. Our experienced sales team can help you identify the options that best suit your needs.
Compressing air is a technology that&#;s been around a long time. It&#;s simply intaking air at atmospheric pressure and then mechanically compressing it to a higher pressure. Most actuator systems that use pneumatic power have compression rates of about 80 to 100 psi.
This limited pressure rate makes pneumatic systems stable and safe. However, the low pressure rating makes them less powerful than higher capacity hydraulic actuators. Selecting a pneumatic system over a hydraulic or electric actuator is also a matter of application.
Pneumatic actuator systems have five main parts &#; a primary motor, a compressor unit, a storage tank, a delivery hose network and the actuator device. In the right situation, such as lighter duty applications, pneumatic systems are good choices. Here are some pros and cons of pneumatic actuators.
Speed is the biggest pro you&#;ll find with pneumatic actuators. Compressed air allows for high-speed motion and energy released. If you have an application where speed is more important than power, then you may consider a pneumatic actuator. Here are some more pros about pneumatics.
The biggest negative you&#;ll find about pneumatic actuators is their limited strength or work capacity. However, if this isn&#;t a concern, don&#;t overlook the value in pneumatic equipment. Here are three disadvantages to compressed air actuation:
Electric actuators have come a long way in a short time. At one point, actuators powered by electricity had their share of problems. They were weak, unreliable and only applicable to very light duty. That&#;s not the case anymore, thanks to advances in technology.
Electric activators work on alternating current that energizes an electric motor. Electric energy converts into torque which drives the actuator. This is a straightforward principle that&#;s becoming far more accepted in the actuator industry.
Electric actuators use mechanical components like lead screws and gears to open and close their applications. The difference between pneumatic and electric actuators is that the electric motor is part of the actuator assembly rather than separate. Once applicable to light-duty work, that&#;s now changing. Here are more pros and cons of electric actuators.
Like any type of actuator, electric actuators can be the right choice when matched with the right job. Here are a few pros that might make investing in electric actuators inviting.
There are some cons to electric actuators, as there are with all mechanical devices. Here are three disadvantages to electric actuators:
Knowing what actuator is best for your application depends on your working environment. That could be a heavy-duty outdoor environment where hydraulic actuators are popular, a fast-moving indoor environment where pneumatic actuators are common or a clean-room environment where the only realistic option is electric actuators.
The main difference between actuators is the power they can handle. All actuators convert some form of stored energy into motion, but their ability to handle that energy and convert it into physical work varies. These are general applications for the three main actuator types:
To appreciate what actuator is best for your application, you have to know the parameters of its work environment and what you expect it to do. There are many more considerations than strength that should influence your actuator choice. Some important issues are:
All three actuator types have unique features. In addition to the specific application you have in mind, you should account for other factors before choosing an actuator type. Some considerations are:
There are more factors involved in selecting the right actuator for your specific application. However, your end choice will come down to the type of power you decide is best for your actuator.
Choosing the right actuator all comes down to your application. You need to have a clear view and understanding of what you want your actuator to accomplish, what environment it&#;s working in and what you perceive as the best return on your investment.
Overall, if you have a big application that needs reliable power, then hydraulics are the answer.
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Actuators are a critical component to the automation process. In fact, most of the heavy lifting for liquids, gases, and discrete motion control is done by actuators. There is an important distinction, however, between actuator applications: process and discrete. The differences between these two worlds are vast, and it can be challenging for personnel inside these two worlds to effectively communicate. This is where Valin's expertise takes over.
In the process industries, for example, there are control valves with actuators specifically designed to open, close, and control them. There are two types of process actuators to discuss: Pneumatic and Electromechanical. Pneumatic actuators are known for better performance in many instances, but there are situations where these are not a feasible option due to the lack of air supply. In these circumstances, the electromechanical actuator may be a better option. When air supply is not an issue, however, the pneumatic actuator is often preferred.
The discrete automation world is a bit different.
In this industry, pneumatics is the least expensive option with the lowest expected performance. Between the leaks, high maintenance requirements and performance limitations, operators prefer to keep everything electric If possible. Thus, in the world of discrete automation, electromechanical actuators have a higher performance and lower maintenance.
So where does the crossover happen?
In the process industries, sometimes the available pneumatic solutions do not meet the given application's performance criteria. In these scenarios, an electromechanical solution may be the better option. Or perhaps you want to be able to control the speed of a valve's closing or opening better...perhaps slower, faster, or some combination of speeds. In this case, the motion control capability of a servo-controlled electromechanical actuator from the discreet automation world is ideal. The challenge is having enough expertise in both worlds to recognize this and be able to make that pivot as needed.
What applications would benefit from electromechanical servo-motor controlled actuators? Any application where the customer would receive financial benefits from higher performance. These benefits could be higher accuracy, better repeatability, more controlled motion, or lower maintenance that results in an improved bottom-line performance.
The key is to have the most comprehensive understanding of the electromechanical options even if you don't necessarily come from the discrete automation world. The specifying can be a little nuanced as there are environmental considerations, and the manual override works much differently.
So, the next time you're in a situation where you're looking for an actuator and the traditional designs aren't necessarily meeting your needs, it may be time to branch out into other industries to find the proper solution.
We contributed an even more in depth look into this topic to Processing Magazine. You can read the full article here.
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