Assessing the trade-offs of making the switch to electrical actuators

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Assessing the trade-offs of making the switch to electrical actuators

Assessing the trade-offs of making the switch to electrical actuators

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Oct 24,24

The focus on the trade-offs of electrical actuators is only a topic of discussion because the transition from hydraulic systems is picking up pace. In following the trend, professionals may forget to consider the drawbacks, writes Emily Newton.

Assessing the trade-offs of making the switch to electrical actuators

Electric actuators have started to replace hydraulic and pneumatic systems. While they promise various operational and financial improvements, the change may not be for the better — at least not entirely. What trade-offs should business leaders expect from making the switch? Are the benefits worth the compromises?

Why electrical actuators are replacing hydraulics

Hydraulic actuators have been considered the industry standard for years. Why make the switch to electric? Perceived value has been one of the top drivers. Experts estimate the market for electrical linear actuators will increase from $20.5 billion in 2022 to $34.3 billion in 2032, achieving a compound annual growth rate of 5.3 per cent.

Increasingly tightening regulations are also driving change. As federal and state governments eye clean energy, high tariffs on crude imports and laws limiting emissions become real possibilities. In an effort to proactively comply with foreseeable changes — and appeal to socially conscious consumers — construction and manufacturing firms are switching to electric.

Still, relatively few real-world examples of all-electric machinery exist to date. Multiple firms have created proof-of-concept models, but they are far from becoming industry standard. Is it because original equipment manufacturers hesitate to break into an unproven field? Or is transitioning to batteries and electrical actuators more challenging than they assumed?

How electric, pneumatic and hydraulic compare

Realistically, decision-makers should expect to compromise on speed, precision or strength regardless of the actuator type they select. The focus on the trade-offs of electrical actuators is only a topic of discussion because the transition from hydraulic systems is picking up pace. In following the trend, professionals may forget to consider the drawbacks.

Hydraulic actuators are purpose-built for power. An industrial-grade version has a one to eight-inch bore size at 2,000 to 3,000 pounds per square inch (PSI) and can exert anywhere from 1,700 to 110,000 pounds of force. These systems have undergone decades of fine-tuning and optimization.

Those purpose-built for specialized applications are capable of even more strength. While typical hydraulic actuator pressure ranges from 1,000 to 5,000 PSI, large systems can reach upwards of 10,000 PSI. They undoubtedly provide the greatest force and power density out of any actuator design.

Electrical actuators, on the other hand, are comparatively weak. They have the equivalent of a one to five-inch bore size and can exert up to 50,000 pounds of force — just half that of a comparable hydraulic system. Achieving a similar power level when generating mechanical power from electrical input may not be impossible, but it is technologically impractical.

The trade-offs of switching to electrical actuators

Since hydraulic systems rely on compressed fluid and have been the industry standard for years, their design simplicity is unparalleled. They are often significantly cheaper to deploy than alternatives. The total cost of acquisition for electric is comparatively high — even pneumatic actuators are more affordable upfront.

Another trade-off of electrical systems is the lack of power. Many real-world machines achieve under 50 kilowatts — the equivalent of 75 mechanical horsepower. This is because it only makes sense to deploy them in applications with one or two actuators. The larger and more complex machinery becomes, the more difficult it is to justify the upfront cost.

Some original equipment manufacturers are attempting to build all-electric heavy-duty machinery. Their power is even lower. For instance, Caterpillar’s battery-powered 793 electric mining truck runs on a 256-kilowatt-hour battery and has an eight-hour charging cycle, meaning it has the equivalent of a 42-horsepower motor.

The problem with electrical actuators is that they require a large amount of space. While they technically take up less room than other systems, they are relatively bulky. A hydraulic system may contain numerous valves, hoses and components, but optimization has made it compact.

Moreover, making these components comparatively strong means even more space is needed. In other words, retrofitting machinery for an electric system may be complex and costly. Professionals will realize as much once they use the load, duty cycle and stroke length to determine the size needed for their application.

What makes these actuators worth the investment?

Despite the potential drawbacks, business leaders can still make the switch to electrical actuators worth the investment. These components may not possess their counterparts' force or power density, but they are highly precise, efficient and cost-effective. Since they are directly driven and rely on electricity, their power source is continuous.

Efficiency-wise, electric systems come out on top. While they can achieve up to 80 per cent efficiency, hydraulic actuators reach roughly 40 per cent on average. This incredible disparity is primarily due to oil's messy, inconsistent nature. Pneumatic systems range from 10 per cent to 25 per cent, readily experiencing decreases as seals degrade and leaks develop in supply hoses.

In addition to being more efficient, electric actuators are also more sustainable and easier to maintain. Unlike alternatives, it does not leak fluids or gasses. There is no messy buildup that requires cleanup or could damage adjacent parts. Having little to no maintenance expenses throughout the machine’s life cycle lowers the total cost of ownership.

Moreover, unlike hydraulic and pneumatic, electric systems do not need to constantly run to keep lines charged. They do not waste energy when idle, saving resource usage and lowering companies’ carbon footprints.

Another benefit is greater motion control. Pairing electrical actuators with a motor system and servo drive enables real-time visibility into the component’s position, speed and acceleration, among other variables. Professionals can customize the speed, stroke length and applied force. A similar setup for a hydraulic system would be expensive and technologically complex.

The bottom line on adopting electrical systems

Companies have several options for optimizing electric actuators to compensate for the various power density and force trade-offs. Maximizing the space in the envelope by making designs more compact is the best way to simplify retrofitting. Customising motion control factors is another way to increase efficiency and speed.

Will machine operators be able to tell the difference? From their perspective, the change is mostly undetectable. Their equipment will be more precise, quiet and responsive. The main difference will be noticed during refueling and maintenance, as charging a battery and fixing electrical shorts are much different than refilling oil or cleaning a fluid leak.

About the author:

Emily Newton is a tech and industrial journalist and the Editor-in-Chief of Revolutionized magazine. Subscribe to the Revolutionized newsletter for more content from Emily.