An actuator uses the potential energy stored in air, electricity, or a liquid to induce a controlled motion. They can alternatively push, pull, lift, lower, close, open, obstruct, or eject an object, in one direction or both.
Because actuators can create a linear, rotary, or oscillating motion, they can be found in a variety of machines and devices. For example, an actuator can move a power-lock in a car, adjust an air vent, or control a backhoe. Their simplicity, versatility, and reliability make them an essential tool in light and heavy industry alike.
Types of Actuators
Actuators can be hydraulically, pneumatically, or electrically powered. Each source of energy carries with it certain advantages and disadvantages.
Hydraulic Actuators
A hydraulic actuator creates motion by applying a force to a liquid. Although they have limited acceleration, they can produce forces that are 25 times greater than a pneumatic cylinder of equal size. Their excellent mechanical stiffness and strong dynamic response leave them well-suited to heavy-duty applications in the manufacturing, marine, aerospace industries.
Hydraulic actuators have many companion parts, but the pumps and motors used to power them can be effectively located at a distance without affecting them. They can be expensive, however, and the inevitable leakage that they produce can undermine their efficiency and affect the cleanliness of surrounding areas.
Pneumatic Actuators
A pneumatic actuator is similar to a hydraulic actuator in principle, using compressed air to move an object rather than a liquid. The increased air pressure causes a piston to move into a cylinder, resulting in a linear or rotary motion. Though suited to a variety of applications, pneumatic actuators are most often used in food and beverage production and heavy manufacturing.
The simple structure of pneumatic actuators makes them safer and more precise than other actuators for certain tasks. However, they must be sized for a specific job and aren’t interchangeable. They can provide movement at high speeds but struggle with slow speeds. In addition, the operating costs of corresponding regulators, valves, and other components can be high.
Electric Actuators
An electric actuator runs on a motor that converts electrical energy into torque. The resulting torque causes a screw to rotate. Electric actuators are common in equipment subject to rapid changes of speed, velocity, and distances traveled such as the mechanisms found in heavy-duty vehicles.
Easy to install and program, electric actuators facilitate smooth, exact, dependable movement. While component costs are high, they have low operating costs and do not directly depend on fossil fuels. They are quieter than hydraulic and pneumatic actuators, but since they can produce fires, they cannot be used around flame hazards.
Industry Applications
All types of actuators can be found in a range of industries, including healthcare, food and beverages, construction, energy, and automotive and aerospace manufacturing. Many of their applications are everyday actions such as turning the ignition key in a car. Here are a few specific uses:
- In office buildings, actuators are used to automatically operate windows for natural cooling ventilation and easier access.
- The agriculture industry uses actuators to not only assist with levers and the opening and closing of valves in combines, tractors, and harvesters but also to tilt egg trays inside incubators.
- The watercraft industry uses electric actuators in jet ski lifts.
- In the food industry, chefs use actuators to cover and uncover dishes on display.
- Medical actuators raise and lower hospital beds, move MRI scanners, and position laser equipment accurately.
Hydraulic, pneumatic, and electric actuators provide effective control over the motion of an object, enabling their users to ensure the consistency of various functions and processes. Indeed, a well-designed actuator can be the linchpin of any industrial process.
Resources:
- What is an Actuator?
- Electric Actuators
- Pneumatic Actuators
- How to Select an Actuator
- Sizing and Selection Criteria for Actuators
- Actuator Zone Education Center
Image Credit: Stanislav Yemets / Shutterstock