Demystify Rotary Actuators: Types, Advantages, and ...

An actuator is either linear or rotary, depending on its motion type. In this article, we introduce you to the rotary actuator, one of the most used devices in the automation world. We explain its operating principle, benefits and types, and application in various systems.

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What is a Rotary Actuator?

A rotary actuator is an output device that turns electrical energy or fluid pressure into angular motion. Note that it can also be a manual type you operate with the hand. Mostly compact, this device can form part of heavy-duty, fluid-based, or hydraulic machinery.

Unlike the linear type, which produces force in a straight line, the rotational actuator generates power within a radius. Depending on the required function, its rotation may be continuous, 360-degree revolutions, or partial and only slightly angular.

Inside a hydraulic rotary actuator
Resource: https://www.designworldonline.com

Rotary Actuator Operating Principle

The working of angular actuators depends on the energy source and the specific design or construction. The energy source is electricity or pressurized fluid, except for the manual types you operate with your hand.

Construction-wise, it uses different mechanisms to work. For example, it can be an electric motor directly operating a gear system or a piston that moves a rack to rotate a pinion gear.

Depending on its required function, the angular actuator may produce partial or complete rotation in either direction, measured in torque.

When used in automated systems, rotary or angular actuators operate alongside sensors and controllers to determine the amount of force, motion direction, speed, position, and other aspects.

Different types of rotary actuators
Resource: https://fluidpowerjournal.com

Rotary Actuator Types

Manufacturers group angular actuating devices by their power or energy sources, which can be manual, electric, or fluid-based (pneumatic and hydraulic). In light of that, we have the following types of rotary actuators:

Pneumatic Rotary Actuator

This actuating device falls in the fluid-powered category. It depends on pressurized air to generate motion and can have many different designs. Options include the following;

• Rack and pinion: a moving rack gear rotates a pinion gear and generates angular motion
• Vane type: compressed air acts on a vane, moving it and rotating a shaft.
• Diaphragm Type: a flexible diagram moves under fluid pressure and moves a mechanical linkage to produce torque.
• Scotch yoke: a piston pushes a movable block along a groove and rotates a coupling to generate rotation.

You can use the pneumatic actuator in many different applications. It controls various industrial processes, including pick and place, valve opening and closing, etc.

Electric Actuator

This version uses an electric current to produce angular motion. It&#;s usually a motor that works a system of gears to control rotation and pass torque to a load.

These motors are typically reversible, with the ability to generate oscillation or angular rotation. They rely on an electric controller to work. The controller (usually with the help of sensors) regulates current as it goes to the motor, directing its operation.

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You may use electric actuating in an automation system or alongside a manual override to open and close a pipeline valve. In industrial settings, they control various processes. They are common in robotic or automotive systems and electrical appliances.

Hydraulic Actuator

The hydraulic type uses pressurized fluid, unlike the pneumatic version. This fluid is typically oil and several other liquids. They can be of various designs, just like the pneumatic types, including the following:

• Piston based
• Vane type
• Diaphragm type
• Scotch and yoke mechanism

Hydraulic angular actuators offer the advantage of generating immense force and are often suited for heavy equipment such as heavy industry machine systems.

Manual Actuator

The manual type uses a gear system to convert motion. Most often, the hand-operated part is a large wheel. Rotating the weal operates a mechanical system, usually worm gear, and directly transmits rotation to the actuating element.

The wheel and worm drive increases the mechanical advantage, allowing you to use less effort to work a big load. It&#;s often a manual override for opening or closing valves, especially quarter-turn valves. These include ball or butterfly valves.

Manual versions of the actuator are inexpensive. They suit situations where an energy source (electricity or pressurized fluid) isn&#;t readily available, or a less costly mechanism would still work.

Hydraulic actuating device construction
Resource: https://www.youtube.com/watch?nyjB1zHxI1g

Rotary Actuator Advantages and Disadvantages

This device offers benefits in many applications. On the downside, it may not suit some uses. Understanding its advantages and disadvantages can help you decide if it fits your needs or requirements. There are various advantages to using an angular actuating device.

• You can generate a high amount of force (torque) using a small device or system
• It achieves greater precision in the actuator movements
• You can easily control its speed and direction of motion
• These actuators are versatile, given their many designs and energy source options

That said, these mechanisms have their limitations. For example, their motion is oscillation or rotation, which can be limiting in some applications. Unless manual, they require electricity or a source of pressurized fluid.

Rotary actuator application
Resource: https://www.researchgate.net

Rotary Actuator Applications

These actuator types are among the most used devices, given their ability to produce angular or oscillatory movements.

• They perform various industrial functions such as packaging, product assembly, valve actuation, CNC machining, etc.
• They help move heavy loads or are part of heavy-duty construction equipment such as lifts and cranes.
• In aircraft, rotary actuation forms the basis of tailing edge or flap operation and other tasks that require great force and reliability.
• In the oil and gas sector, they open and close valves and are essential in off-shore cranes, winches, and other equipment.
• They cause movements that adjust beds, operating tables, and other equipment in the medical world.
• In robotics, they operate arms, jaws, and several other parts with greater accuracy and repeatability.

When selecting a rotatory actuating device for your application, it helps to consider the following essential specifications:

• Device torque, or its turning force, usually expressed in Nm (Newton-meter)
• The angle of rotation, which can vary from 0 to 360 degrees
• The speed in RPM or, in other words, the time it takes to reach the required position
• The IP rating, especially if your application is in an outdoor environment
• Accuracy level or how precise the device is in its specified application
• The operating temperature range, depending on the application environment

Conclusion

There you have it, an overview of the rotary actuator. These mechanisms transform electric or fluid power into angular or oscillatory motion, or it can be a manual device that you operate with your hands. Today, these devices are available in many options, from modular to compact and intelligent actuators.

Geya is a leading manufacturer of rotary actuators. We are dedicated to steering your business towards more tremendous success. Take advantage of the opportunity to elevate your operations with our expertise. Please get in touch with us immediately.

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