Electric actuators displace other motion options — including manual designs: A Motion Trends report

Oct 04, 2023

By Lisa Eitel | March 1, 2019

Today, electric actuators are easier than ever to specify and install. Value-add services from component suppliers as well as application-specific actuator product lines (especially for battery-powered designs in mobile equipment and consumer use) eliminate many integration tasks for OEMs and end users. These are trends supported in part by a movement Design World has tracked for the last several years — that of increasingly pre-integrated motion builds. Fastest growth is in compact motion designs aimed at replacing manually operated functions.

LINAK linear actuators power retractable operator-cab stepladders of off-highway equipment and make it easier for workers to climb up into (and climb down from) the elevated cab area. Read the full application story here.

Jonas Proeger • Trinamic Motion Control: The big overlying trend we see is what some call the Fourth Industrial Revolution. Two important things follow out of this:

• More and more aspects of human life are being automated … including functions serviced with large machines as well as small everyday tasks.

• Software-defined machines are seeing exponential rise in use. A perfect example of this is the 3D printer: These machines can fabricate anything provided with appropriate software. But it's not just 3D printers … in fact, software-defined machines also enable new fabrication plants that nowadays aren't built for one product alone … but rather accept reprogramming or even modification of every part manufactured according to customer demand — for what industry calls mass customization.

As products and machines are increasingly software defined (without any change to the machine physics) we think lower-level functions (such as motor control and ramping) should be done in proven building blocks that keep working reliably — even when the application software changes. What's unique about Trinamic offerings is the partitioning between hardware (where our designs execute motor control and software tasks) which our customers leverage for communications stacks and application code.

In the past, most actuators were built by OEMs that would buy motors, rotary-to-linear devices, and couplings and then execute assembly in-house. Today, specification of turnkey electric actuators is the norm for projects involving just a few or thousands of axes.

We cover the increase of electric-actuator programmability (and how component suppliers and their distributors are supporting some of this work) below. But besides trends related to I4.0, Proeger of Trinamic Motion Control (quoted above) notes more aspects of human life being automated. Read the LINAK application feature accompanying this piece for one example related to increasing ergonomics of off-highway machinery.

Others see the same trend — especially for electric actuators.

Dave Humblet | Senior application engineer with PBC Linear: Some recent applications illustrate the trend towards more OEMs incorporating accessibility and serviceability features in their designs with actuators and other linear-motion designs. In one instance, linear actuators provide cab movement on a trenching machine for operator visibility. More specifically, this design uses PBC Linear CCR16 linear shafting and FLN16 standard linear bearing in a customer housing. Advantages here include availability; good load ratings; and robust design.

Tolomatic IMA linear servo actuators, in standard and food-grade models, feature hollow-core rotor design, allowing the nut of the screw to pass inside the rotor. This compact package can decrease overall actuator length compared to standard actuators due to the elimination of a separate motor, motor mount and gearbox. Photo courtesy Tolomatic Inc.

Another big trend in electric actuators is their use in replacing pneumatics.

Peter Zafiro • LinMot USA: Most actuators in industry are pneumatic. Anybody who says otherwise doesn't spend enough time in typical automated production plants. Even in nonautomated plants, there's lots of air being used. That means there's still a lot of room for electric actuators … these motion components are getting easier to use. This means we need to step up and educate end users on how expensive compressed air can be — even at the ultra-cheap electrical rates we have in the U.S. Plus, you must factor in the noise….and the maintenance…and the hassle of frequent repairs.

One plant manager used our product for 18 months in an exact duplicate of a pneumatic application. The liner motor electric actuator we provided worked better than the pneumatic cylinder and resulted in greater productivity. It wasn't until we brought in a high-efficiency compressor, created a perfectly leak-free air-delivery system to run his pneumatic cylinder machine, measured the kilowatt hours used, and compared this to the linear motor electric actuator machine, that he accepted our electric actuator solution. The LinMot solution used 3% of the electricity that the air cylinder did. It cost him well over $5,000 a year to run the pneumatic cylinder in electricity … the ROI for the electric replacement was less than a year.

Many plants making production parts run profit margins of less than a penny per part. Providing $5,000 in added profit per year — that is huge.

Other benefits of electric-actuator technologies over fluid-power offerings are their lower maintenance and programmability — for full leveraging of sensor data and load monitoring … sometimes in real time. Even so, many engineers incorrectly assume pneumatics and linear motors have very little overlap in applicability.

Zafiro • LinMot: In some cases, linear motors are a direct replacement for pneumatics. The upfront price penalty is quickly offset by lower total cost of ownership. Of course, not all pneumatic applications use significant kilowatt hours … but many linear-motion applications sure do. That's because moving from A to B with an attached load causes lots of air displacement in the cylinder.

Even so, most end users still won't switch. The stigma is that linear motors are high-end drive technology and pneumatic cylinders are simple. Even though replacing the most basic with the most sophisticated technology seems like overkill to some engineers, in practice it's not. Direct-drive systems exhibit no heat losses associated with ballscrews, gears, belts, couplings, and other intermediate drivetrains. Our linear motors are also sealed against contamination … even to IP69K laser welded protection.

The reality is that linear motors don't make sense for every application … though make sense for many. Moving a distance greater than 100 mm with a frequency greater than every 2 second, and any type of load attached — you can bet that you’re using a lot of air. So why not go with the most efficient system for point-to-point positioning and picking and placing?

Linear motors also excel in threading and capping applications with repeated up-down-rotation movements — where a rotary motor is attached to the linear motor.

Still other advancements in mechanical devices for linear actuators abound. Some of these also take aim at conventional fluid-power offerings.

Aaron Dietrich • Tolomatic: Strong growth in the deployment of roller screws originates from requirements of more force capabilities into smaller package sizes when displacing hydraulic-cylinder technology. Not only must the forces be reached, but the screw technology must provide very long life in demanding applications and also be able to withstand machine vibrations and other challenging environments.

Dave Beckstoffer | Product manager • Portescap: The continued trend in linear actuators is size reduction while maintaining a high force output. Portescap continues to develop new linear actuators capable of increased linear force while maintain the same outside diameter.

In addition, external linear-actuator designs can provide added options utilizing different technologies — including brush dc motors and gearboxes. Alternate technologies help reduce the diameter of the motor solution while providing flexibility in the leadscrew pitch.

Stefan Vorndran • Physik Instrumente (PI): We see more interest in piezomotor-driven miniature actuators for applications where space and power are limited and requirements for precision are high. Piezomotors are smaller and more efficient than traditional miniature motors and piezomotor actuators can very stably hold position without the need for continuous power or a mechanical brake. The small actuator size allows for the construction of very small positioning stages as well.

No matter the motor or mechanical-actuation type, predesigned actuator subassemblies are widespread these days. Customization for OEMs is sometimes useful where an axis may need to move faster than standard product is capable … or software may need to accommodate specialty communications requirements.

Choosing between assembling components or getting them integrated in advance lets OEMs and end users control the time and effort they put into motion-design tasks … including those related to motor and drive matching and customization for specific applications. Such designs often yield smart actuators that include cabling and connectors, potentiometers, encoders, controllers, relays, and embedded electronics for networking. Where component suppliers or their distributors assume some of the actuator programming, OEMs and end users can expect even more support.

Dietrich • Tolomatic: Integrating multiple technologies into a single modular motion control solution helps machine designers create more compact machine designs. For example, Tolomatic's IMA product line is an optimized solution with matched components. It integrates the mechanical actuator and servo motor into one actuator module.

With integrated actuator solutions, the machine designer has only one mechanical design independent of a servo control supplier. This reduces component count and eliminates the need to mount the motor to the actuator. Furthermore, the integrated actuator components are optimized for performance, cost, size and weight.

Patrick Wheeler | Product manager • Aerotech: Controls technology is moving towards embedded solutions. That means more and more, the PC has to prove its way into the application … and the PC is no longer the starting point. We’re also seeing a trend towards more advanced programming languages over traditional IEC languages such as ladder and structured text. Not to say that there's some global move away from IEC … but the increased use of advanced programming is an emerging trend. In fact, more and more often we hear of customers who are willing to take on new languages to complete jobs … although they do want the language to be familiar and adhere to modern language constructs.

How is the increased integration of linear actuators helping OEMs?

Dan Schmit | Product manager • Tolomatic: Integrated actuators let OEMs better support customers through easy replacement of motion modules versus troubleshooting components of a traditional actuator-gearbox-belt system. This also helps reduce the number of purchased components in the machine design (in line with purchasing trends and best practices). In the food-and-beverage industry, trends towards more compact solutions and open machine designs, require integrated actuators capable of washdown to improve ease of cleaning, machine reliability, and achieve an open clean-in-place machine design.

General industry trends see OEM activity to improve cycle time and process reliability, requiring long life and high performance from actuators. That is achieved through design choices of various screw technologies (ball and roller screw considerations) as well as stator windings specially designed for force repeatability and dynamic response — including skewed windings and those with low electrical time constants. Easy integration and multiple mounting options also let OEMs go global and use the same mechanical machine design (form, fit, and function) to support customers internationally with different controls systems.

Thomson Industries MOTIONEERING sizing software lets design engineers (among other things) use a part numbering selector to quickly find linear-motion solutions. In this way, immediate access to 3D models and technical information is available.

Sizing software and online purchasing tools continue to change the way linear actuators are engineered into designs — just as they’ve changed consumer purchasing habits.

Case in point: Linear-motion eTools from Bosch Rexroth (Linear Motion Designer, LinSelect, and eConfigurators) help users get information and then select, purchase, supply, commission, startup, operate, and service designs. For the latter, the manufacturer's ActiveCockpit data-visualization tool allows tracking of plant data in real time.

The way in which younger engineers prefer self-guided research (versus high-touch selling models) is helping to drive this online purchasing and specification. Design engineering in emerging markets such as eastern Europe and Sino Asia is also supported heavily by online tools. Of course, critical mass in regional markets still supports traditional sales approaches — especially where engineers want to collaborate with knowledgeable supplier representatives who can visit in person.

Travis Gilmer | Product line specialist for industrial linear actuators • Thomson Industries: We recently expanded our Linear MOTIONEERING online sizing and selection tools with a platform for linear actuators. These products have commonly been challenging to size into new applications due to the various product family groups that overlap. This can result in costly and time-consuming misapplications. So we set out to simplify this process by establishing a list of 20 or so questions that most accurately identify the correct product for a specific application. The result is a more application-focused look at a wide range of feature options than what design engineers might otherwise find from searching on their own.

A design engineer can log into our self-service sizing tool from their PC, mobile phone or tablet, make real-time adjustments, recalculate per their defined parameters, and download CAD-ready 3D models and 2D projections of the project to help assimilate the custom-fit product to their overall applications and designs. Plus, not only can they save project work and sizing efforts, they’re able to place an order for the linear actuator directly within the platform.