In this chapter, we will explore the fundamentals of electric actuators, such as their production techniques, integral parts, functional principles, and effectiveness.
Electric actuators are mechanisms that move a load or perform actions requiring force, like clamping, by utilizing an electric motor to generate the needed force.
The electric motor induces rotary motion in the spindle or rotor. Inside the actuator, a helical screw links to the motor spindle via the drive shaft, spinning within a ball screw nut.
The creation of electric linear actuators begins with the electric motor, which includes two primary sections: the stator, a fixed permanent magnet, and the rotor, situated at the stator's center, revolving within the magnetic field generated by the stator.
Every part is precisely crafted on an automated assembly line inside the electric actuator plant. The process is continuously monitored, from coiling the rotor's copper to fitting the shaft screw. Quality assurance rigorously checks each production batch. Efficiency is increased by producing different motor parts concurrently, facilitating the efficient assembly of each linear actuator.
Mechanical arms and conveyor systems transport raw materials and finished components to subsequent production stages. Following assembly, trained workers finalize assembly under detailed guidance documented by engineers. Quality assurance specialists conduct thorough inspections at each production step.
Fully assembled actuators are sent to Quality Control for a first article inspection, confirming dimensions and meeting all standards. The initial unit is stress-tested to ensure compliance with IP ratings, operational temperature ranges, and duty cycle specifications.
Upon passing Quality Control, the batch is cleared for the distribution center shipment. Products are re-evaluated by a product engineer upon reaching the warehouse to confirm adherence to specifications and absence of transport damage.
After verification, products enter stock ready for sale. Post-purchase, logistics conducts final testing before secure packing and preparing units for shipment.
This section delves into the various components making up an electric actuator.
This U-shaped metal piece features holes at each end to accommodate a pin, bolt, or other fasteners. It allows actuators to attach to applications with front and rear clevis fittings for secure mounting.
Known also as the cover tube, this extruded aluminum tube shields the linear actuator's external parts and houses all inner components.
Also referred to as the extension, translation, piston, or drive tube, this part, typically made from aluminum or stainless steel, holds the spindle during retraction. It's connected to the threaded drive nut, which travels the rotating spindle to extend or retract the tube.
Known as the rotating screw, lead screw, or lifting screw, the spindle is a straight rod rotating within a machine, controlling the inner tube's extension and retraction. Crafted from durable steel, it can be threaded in various ways for differing speed and load specifications.
This feature, at the spindle's end, prevents the inner tube from overextending.
Attached to the outer tube's end, the wiper seal stops contaminants like dust and liquids from invading the spindle area. It ensures a proper seal between the inner and outer tubes, influencing the actuator's IP rating.
Sliding along the spindle and attached to the inner tube, the drive nut facilitates retraction and extension. Can be made from plastic or metal, and sometimes keyed to avert inner tube rotation.
These switches control the inner tube's position when fully extended or retracted by halting the motor’s current. They prevent overextension or overretraction and can send signals.
Constructed from plastic or steel, these gears interact with other gears to modify speed relationships between the driving mechanism and driven parts. The gear linked to a power source like a motor is the drive gear.
This enclosure protects the gear motor and internal components from damage, typically made from high-quality plastic.
The actuator derives its power from the direct current motor. DC motors are available in various types, with brushed motors being the most common. Each motor comprises these parts:
The stator is the motor’s stationary exterior, comprising housing, caps, and two permanent magnets, creating a magnetic field around the rotor.
Also called the armature, the rotor is the inner rotating motor part, including the shaft, steel laminates, copper windings, and commutator.
Mounted on the motor shaft, these plates connect with the electromagnet coil. The commutator reverses polarity, maintaining rotation and preventing torque loss.
Carbon brushes transfer current using sliding friction from the stator to the rotor.
This connects the gear motor to the DC motor’s stator base.
These sensors relay the actuator’s stroke position to the control box MCU, crucial for applications needing precise operations like synchronization and position memory. Available output sensors include:
This sensor provides a signal based on surrounding magnetic fields. When magnetic density surpasses a threshold, the sensor produces Hall voltage as output. Position feedback from a Hall sensor enhances accuracy and trustworthiness in linear actuators.
Featuring a wiper and end connections, this sensor adjusts the electrical signal output. The linear actuator’s lead screw rotates, altering resistance between the wiper and connections, each corresponding to a specific actuator position.
A magnetic device working as a switch activated by a magnetic field. With ferrous metal reeds in sealed glass, contacts usually remain open but close under magnetism, completing the circuit and halting actuator power.
In creating rotary motion, the electric motor induces spindle or rotor rotation. Coupled to a helical screw via the drive shaft, the motor spindle spins within a ball screw nut.
The ball screw nut moves longitudinally on the helical screw as the spindle turns, coupling with a hollow piston rod to convert motor rotation into straight linear motion. This action depends on motor rotation direction, either clockwise or counterclockwise.
The actuator's movement is managed via an electric drive, adjusting rotation speed and linear velocity. A feedback system allows precision, like moving to designated positions, pausing movement, or returning to a start point.
Torque output corresponds to motor power, determining the actuator's effective force capability.
```Electric actuators play a crucial role in modern industrial automation, providing highly accurate and reliable motion control in a diverse range of applications. Understanding the different types of electric actuators is essential when specifying a solution for automated systems, machinery, robotics, or process control. Below, we explore the primary types of electric actuators and their unique features, as well as how electric actuators compare to their pneumatic and hydraulic counterparts in terms of performance, cost, and application suitability.
A smart linear electric actuator delivers precise and controlled linear output displacement, making it a go-to choice for automated positioning tasks in industrial automation, motion control systems, and factory robotics. Engineered with high-quality, robust materials, this linear actuator ensures long-term durability, safety, and minimal maintenance. Thanks to integrated smart controls, these actuators offer real-time feedback and positioning accuracy, optimizing efficiency in applications such as valve actuation—specifically for regulating ball valves, butterfly valves, and gate valves. Their programmable features provide flexibility for complex sequencing and remote monitoring, making them ideal for process industries, automated production lines, and advanced manufacturing environments.
Rotary electric cut off actuators are designed to convert standard electrical control signals into precise angular (rotary) displacement, making them invaluable for valve automation, rotary conveyors, and rotary positioning systems. These actuators provide automated mechanical control of rotary valves, including quarter-turn ball valves and butterfly valves, supporting both local and remote operation with swift response times. Their internal servo amplifier enables accurate feedback and high-speed, bi-directional movement without manual intervention. Industries such as water treatment, oil and gas, and HVAC systems rely on rotary electric actuators for reliable automatic adjustment and flow regulation tasks, where repeatable positioning and integrated safety features are paramount.
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By offering integrated automation and precision, these actuators reduce downtime and facilitate efficient process control. The system typically comprises two main elements: the actuator itself and the servo amplifier, allowing either physical or remote control modes. The modular design streamlines installation and maintenance in industrial environments.
A linear electric cut off actuator is engineered for applications requiring precise reciprocating linear motion based on feedback from process control systems. Available in both AC single-phase and AC three-phase power supply configurations, these actuators excel in positioning regulating valves and dampers with high force output and repeatability. Leveraging closed-loop control technology, the actuator optimizes the valve’s position by interpreting electronic signals and responding with smooth linear movement. Typical industries utilizing this type of actuator include metallurgy, power generation, pulp and paper, environmental protection, petrochemicals, and light manufacturing. Their robust construction and advanced control algorithms enhance system reliability, energy efficiency, and process safety.
Features such as customizable stroke lengths, overload protection, and easy integration with PLC or DCS systems make linear electric cut off actuators a preferred choice for motion control solutions in demanding industrial settings. These actuators also help reduce manual intervention, boosting operational efficiency and process consistency.
This advanced rotary electric actuator features comprehensive electronic controls, supporting industry-standard input signals ranging from 4mA–20mA or 1V–5V DC, making it compatible with a wide variety of automation and process control systems. Powered by a single-phase AC supply (typically 220V), it integrates a high-performance servo system within its enclosure, eliminating the need for an external servo amplifier. The use of complex, mixed integrated circuits ensures robust signal processing, operational resilience, and longevity. Tested for enduring aging effects, these actuators perform reliably under harsh industrial conditions, including environments subject to moisture, vibration, or electrical noise.
For installation, the actuator allows for flexible orientation of the rotary arm or crank, and its adjustable zero-point range (0 to 360 degrees) enables broad configurability for any actuator-driven valve. Built-in safety mechanisms—including thermal overload, torque limitation, and position feedback switches—provide safety and reliability in automated valve control. These features make rotary electric regulating actuators suitable for HVAC, water treatment, chemical processing, and advanced process automation where precise angle regulation and high reliability are required.
The SMC electric actuator family is known for delivering exceptional performance, accuracy, and repeatability in motion control applications. These actuators offer seamless, programmable acceleration and deceleration, achieving multiple stop positions with high repeat accuracy. By eliminating the need for compressed air, SMC actuators are more energy-efficient, environmentally friendly, and cost-effective to install and operate. Their user-friendly parameter setup and quick-start operation simplify commissioning in both factory automation and laboratory automation applications.
Available in multiple configurations, including slider types, AC servo sliders, rod and guided rod versions, AC servo rods, rotary actuators, electric grippers, miniature actuators, and slide tables, SMC electric actuators are suitable for pick-and-place robots, machine tools, packaging automation, and electronics assembly. Integrated drivers and controllers enhance motion sequencing and diagnostic feedback, supporting Industry 4.0 smart manufacturing initiatives and enabling predictive maintenance. Their versatility, ease of installation, and expanded compatibility with automated control systems make them a favored solution for demanding precision motion applications.
Choosing the right actuator technology—be it electric, pneumatic, or hydraulic—requires careful evaluation of application requirements, cost structures, performance needs, and long-term operational goals. Below is a comprehensive comparison to assist in decision-making for actuator selection.
When comparing electric actuator systems with pneumatic actuators, several critical differences become apparent:
The primary distinction lies in the power source. Pneumatic actuators operate using compressed air (typically 60–125 PSI), controlled through solenoid valves powered by AC or DC voltage. Electric linear and rotary actuators, meanwhile, use electricity to drive motors, making them ideal options when a reliable air supply is unavailable or impractical. Electric actuator systems are especially beneficial in environments prioritizing energy efficiency and simplified infrastructure.
In terms of footprint, double-acting pneumatic actuators are up to 70% more compact than most electric actuators. However, ongoing advancements in electric actuator design are helping close this gap, with miniaturized, efficient models emerging for space-constrained automation applications.
Pneumatic actuators excel in rapid actuation, often cycling valves in half a second to one second based on the design. Electric actuators, including stepper or servo-driven models, may take six seconds or longer for the same stroke. Advanced servo motor actuators can improve electric actuator speed while preserving precision and control, broadening their suitability for high-throughput systems.
Pneumatic actuators operate reliably across a wide temperature spectrum, ranging from -20°F to 350°F, making them suitable for harsh process environments. Electric actuators are typically rated for more moderate temperatures (40°F–150°F), though high-performance industrial models with special thermal management features can handle extremes. Always consult product data sheets to match environmental compatibility.
Pneumatic actuators featuring rack and pinion mechanisms can endure up to a million actuation cycles when properly maintained. High-grade electric actuators, especially those with low-wear components and brushless motors, routinely achieve or exceed 250,000 cycles, with premium models offering even longer lifespans in controlled environments.
A spring-return or failsafe function is essential for safety-critical applications, ensuring actuators default to a safe position during power loss or failure. While pneumatic actuators widely offer spring-return configurations, electric actuators may require additional design considerations—such as built-in battery backups or specialized motor brakes—for automatic failsafe actuation in industrial automation systems.
Electric ball valve actuators typically have a higher initial investment than pneumatic valve actuators. However, their lower long-term maintenance, absence of an air supply infrastructure, and superior energy efficiency often yield significant cost savings and operational value. Pneumatic systems, conversely, are favored for simple, repetitive high-speed operations where compressed air resources are readily available and ongoing maintenance is routine.
Comparing electric actuators with hydraulic actuators provides further insight into which actuation solution best matches specific industrial requirements, especially where force output, control precision, and environmental factors are critical considerations:
Hydraulic cylinders excel in delivering extremely high forces (e.g., up to 15,000 lbf for a 3-inch cylinder at psi), often making them essential in heavy machinery and press operations. Electric actuators generate force via servo motors and roller screws, with immediate torque output and precise feedback. For many motion control and automation applications, electric actuators provide ample force while reducing oversizing and energy loss found in some hydraulic systems.
When optimizing for accurate force application and energy efficiency, it’s vital to match actuator specifications to system load requirements to prevent over-sizing, whether using hydraulic or electric systems.
Hydraulic actuators perform admirably in simple positioning tasks but demand costly servo-hydraulic packages for intricate motion profiles. Electric actuators, by contrast, offer unmatched closed-loop control of position, speed, acceleration, and applied force, with fine-tuned programmability and real-time adjustments. This superior precision enables complex coordinated automation in industries like packaging, CNC machinery, and robotics.
To achieve rapid movements and high force, hydraulic cylinders depend on a stable supply of pressurized oil and often require accumulator systems to buffer pressure variations. In contrast, electric actuators—driven by high-RPM servo motors and efficient ball- or roller-screw mechanisms—are designed for optimized motion profiles, allowing for precise, high-speed, and repeatable actuation cycles. Motor and drive tuning further enables advanced speed and torque control for seamless integration in automated assembly lines.
Although hydraulic cylinders themselves are typically compact at the point of actuation, their required hydraulic power units, hoses, reservoirs, and supporting subsystems occupy valuable factory floor space. Electric actuators integrate the servo or stepper motor, drive, and control electronics within a compact package, significantly reducing system footprint and simplifying installation—making them especially attractive in modular, scalable, or space-limited automated equipment.
Hydraulic actuation systems suffer from performance losses in extreme temperatures due to changing fluid viscosities and potential seal degradation, resulting in inconsistent or sluggish motion and higher maintenance costs. Electric actuator systems can be specified with thermal management features (like extreme-temperature grease and temperature monitoring) to operate reliably across controlled temperature bands and are less susceptible to environmental fluctuations, further reducing life-cycle costs and minimizing unplanned downtime.
While hydraulic cylinders deliver long service life when maintained, maintaining oil quality, seals, hoses, and managing potential leaks results in higher lifetime maintenance requirements and costs. Electric linear actuators, built with quality components and sized for the application, generally require little or no routine maintenance. Many manufacturers offer predictive maintenance features with built-in sensors for life-cycle analytics, minimizing unscheduled downtime and reducing total cost of ownership (TCO).
Modern automation increasingly relies on real-time data and system integration for diagnostics and process optimization. While basic hydraulic systems lack built-in monitoring, electric actuators support intelligent feedback—tracking position, speed, force, and alarm status via PLC or SCADA systems. This intelligent connectivity supports IIoT (Industrial Internet of Things) implementations, enabling remote monitoring, troubleshooting, and proactive maintenance in digitally connected manufacturing environments.
Energy efficiency is a major consideration for facility managers seeking to reduce operational costs. Hydraulic actuation generally operates at 40–50% efficiency, with significant energy losses during pressure conversion and in ancillary systems. Advanced electric actuators routinely reach 75–80% energy efficiency, translating to substantial cost savings and reduced environmental impact over time.
Hydraulic systems present environmental risks due to potential for oil leaks, contamination, and disposal hazards—requiring rigorous spill prevention and response measures. Electric actuator systems are inherently cleaner, with the only byproduct being periodic lubrication maintenance (e.g., grease on roller screws). Environmentally friendly lubricants and sealed designs further minimize ecological impact, supporting sustainability goals and compliance with modern environmental standards.
In summary, selecting the right actuator technology hinges on assessing factors such as application load, required speed, extreme environmental conditions, installation space, energy consumption, safety protocols, and data integration needs. As industrial automation evolves, the flexibility, efficiency, and scalability of electric actuators increasingly position them as viable alternatives to traditional pneumatic and hydraulic systems in most modern manufacturing settings.
This section explores the various applications and advantages of electric actuators.
Electric actuators find use in a variety of applications, including:
Electric actuators offer several advantages, including:
Electric actuators are more straightforward to integrate compared to hydraulic or pneumatic systems. They often come with programmable controllers and microprocessors that facilitate the operation of modern industrial equipment.
Electric actuators provide exceptional precision in motion control. They allow for precise adjustments in torque, speed, and force at various stages throughout the motion process.
Unlike their hydraulic and pneumatic counterparts, electric actuators are not prone to contamination or leaks. This makes them cleaner and more secure, offering a more convenient solution for many applications.
In the long term, electric actuators are often more cost-effective compared to other types. They require minimal maintenance, are simple to operate and install, and are built to endure various environmental conditions. Their durability and reliability further contribute to their overall value.
Additional advantages of electric actuators are detailed below:
Some of the disadvantages of electric actuators include:
Despite their drawbacks, the advantages of electric actuators far exceed their disadvantages.
Electric actuators are essential for applications requiring force. Unlike pneumatic linear actuators, which produce force through pressure on a piston, electric actuators rely on the motor's torque capabilities to generate force. When selecting an actuator, it's crucial to consider factors such as the load to be moved, surface friction, and the load's angle of elevation or decline.
For pneumatic actuators, the distance the load needs to travel determines the actuator’s stroke length. Electric actuators have similar requirements but with some nuances. To avoid overextension, the maximum stroke should be the usable stroke but should not exceed four times the pitch of the helical screws. Electric actuators offer multiple positioning options, so the total movement should match the required stroke. Various screw pitches are available based on the bore size, allowing for versatile component combinations to suit different application needs.
Choosing between electric and pneumatic actuators depends on the availability of compressed air. If compressed air is not available and hydraulic options are not an option, electric actuators become the preferred choice. They are especially advantageous for applications requiring multiple positions, and they offer benefits such as low noise, high precision, rigidity, controllability, and reduced operating costs.
Electric actuators provide exceptional control and precision in positioning. They enhance machine adaptability to flexible processes and are cost-effective due to their energy efficiency, often resulting in significant savings.
Electric actuators are particularly advantageous in applications requiring precise multiple positions. Unlike pneumatic cylinders, which need various accessories to achieve similar functionalities, electric actuators maintain high accuracy and efficiency over time. Additionally, they excel in responsiveness, starting and stopping almost instantaneously compared to hydraulic or pneumatic systems.
Electric actuators operate without delays or lag. In contrast, pneumatic cylinders require continuous compressor operation to maintain pressure. Electric actuators only operate when needed, which can lead to substantial savings on electricity costs for your business.
Electric linear actuators are devices that convert electrical energy into motion. There are different types of electrical actuators offering different capabilities. Electric actuators are more advantageous than their counterparts since they can be easily assembled, are more precise and cost less, only to mention a few benefits. They can also be safely used in a wide variety of applications.
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