Traditional pneumatic and hydraulic actuators are common in automation. They provide solutions to many simple point-to-point linear positioning applications. They have also been the go-to solution for many years because of their inexpensive up-front cost. However, they have several hidden costs that make these solutions expensive over their usable life.
The Advantages of Electric Actuation
Electric-powered linear actuators offer significant efficiency, simplicity, and design advantages, as well as long-term cost savings.
Electric actuators have fewer system components compared to hydraulic and pneumatic systems and require less maintenance. Let’s compare.
- Electric Actuators: You basically have the actuator, motor (servo or stepper), a few cables, and an amplifier (drive). (Simple, right?)
- Hydraulic System: In a typical system, you have a power unit, control valves, pressure gauge(s), oil tank heater, accumulator, flow control valve, suction screens, heat exchangers, filters, and a manual override pump. (Wow. That’s a lot to specify and worry about!)
- Pneumatic System: In a typical (air) system, you have a compressor, intake filter, cooler, separator, receiver, pressure switch, secondary air treatment, control valve(s) and the actuator. (Again, a lot of stuff to specify and worry about!)
Given that both the pneumatic and hydraulic solutions each have several components compared to an electric solution, they present many costly considerations including maintenance, spare parts, and downtime long after you have spent the money on the initial hardware.
A significant advantage of using electric actuation is the ability to have infinite control over the position within the stroke limits of the actuator. If your product size changes, you simply program a new position versus having a maintenance person adjust your machine at changeover. This reduces production downtime and potential waste at product changeover. With electric actuators, you can also program multiple positions and profiles given your production requirements. And if true coordination with other motion is needed, it can be easily accomplished with today’s motion control systems.
Some inherent energy cost savings come from using electric actuation. If you think about typical pneumatic and hydraulic systems, they both require a motor running continuously for them to operate. This motor either runs an air compressor or a hydraulic pump. Depending on your cost per kilowatt hour for energy at your facility, just running these systems can be quite expensive. Another thing to consider is that leaks in these systems are costly! They force your systems to run more than they need to keep up with the desired pressure and flow based on the application requirements.
With electric actuation, energy is only used when the motor on the actuator is moving/running. Be sure to check with your utility provider for incentives that may be available for moving to electric actuation.
Another benefit to electric actuation is the amount of information that you have access to. Position, velocity, current, and force feedback are all easily accessible in your control system. Imagine how nice it would be to fire an output based on the position of your actuator to trigger another function or process. You can even use this information for predictive purposes. For example, as the current required to move your load increases over time, it could mean that service to your mechanical system is required. How great would it be to predictively alert your machine operator?!
Types of Electric Actuators
There are a few common types of electric actuators. Belt and screw-driven systems allow the user to mount the motor of choice (stepper or servo) to them. There are several styles offered in both the belt and screw-driven arrangements.
Rod-style actuators are a great replacement for traditional pneumatic and hydraulic cylinders. They have high force capability (40,000lbs or more) and speeds up to about 100in/s. Some have a similar form factor to pneumatic cylinders, which make migrating these much simpler.Belt-style actuators offer long travel lengths as well as high-acceleration and high-speed capabilities. Depending on your load, it’s not uncommon to achieve 500-600 in/sec2 (or more) for acceleration with speeds upward of 200 in/sec.
Integrated actuators offer a great packaged solution because you essentially have a motor built around a screw-driven actuator. This style of actuator offers a good force rating (up to 10,000lbs or more) in a small footprint.
We Can Help You Make the Change
If you’re looking for ways to increase your machine availability, reduce energy costs, increase your throughput, or improve your repeatability and accuracy, please reach out to one of Horizon Solutions Motion Control Specialists today!