Actuators and Their Applications in Industrial Automation

In the previous chapter, we related the way humans function to automation. The eyes, touch, and smell were likened to switches and sensors while the controller was likened to the brain. In this chapter, we will be looking at actuators, which can be likened to the hands. In our bodily system, the hands do what the brain tells them to do. Similarly, in automation, the actuator does what the controller tells it to do. An actuator is simply a mover. It can move, carry, or perform other similar functions just like the hand. It requires a control signal from a controller to carry out its actions. The control signal is the result of the processing done by the controller through the program (a set of instructions) written into it. Industrial automation is not complete without an actuator.

This chapter will explain various actuators used in industrial automation. You will learn their basic principle of operation and about their application...

3 Actuators and Their Applications in Industrial Automation

In the previous chapter, we related the way humans function to automation. The eyes, touch, and smell were likened to switches and sensors while the controller was likened to the brain. In this chapter, we will be looking at actuators, which can be likened to the hands. In our bodily system, the hands do what the brain tells them to do. Similarly, in automation, the actuator does what the controller tells it to do. An actuator is simply a mover. It can move, carry, or perform other similar functions just like the hand. It requires a control signal from a controller to carry out its actions. The control signal is the result of the processing done by the controller through the program (set of instructions) written into it. Industrial automation is not complete without an actuator.

This chapter will explain various actuators used in industrial automation. You will learn their basic principle of operation and about their application...

Introducing actuators

An actuator is a device or component that produces an action or motion. It can be referred to as a mover because it moves to control a system. It usually requires a control signal from a controller and an energy source, which can be electric, pneumatic (air), or hydraulic (liquid). When it receives a control signal, it converts its own energy (electric, pneumatic, or hydraulic) to a form of energy or motion that can perform the required action.

One major application of an actuator in industry is the opening and closing of valves.

Manually operated valves use hand-wheels, manual gearboxes, knobs, and so on as their actuators for operation. The hand-wheel or knob can be turned clockwise or counterclockwise by humans to open or close the valve.

In situations where manual actuation of a valve to open or close it is not realistic, such as remote locations or on very large valves, a pneumatic, electric, or hydraulic actuator is required.

The actuator (pneumatic, electric...

Learning about electric actuators

Electric actuators are used in industry to convert electrical energy to kinetic energy to cause the movement of loads or perform actions that required motion or force. The operation of most electric actuators is based on the interaction between a magnetic field and a current carrying a conductor to create a turning force. Industrial fans, blowers, pumps, dampers, and so on are common applications of such an electric actuator. They utilize electric motors to perform the necessary action. Electric actuators are used in robotics and other assembly applications due to their accuracy, flexibility, and low operating cost. They are used in industrial machines that require circular motion. They are also used for clamping, pressing, cutting, stamping, and other forms of applications that require linear motion.

An electric actuator can be referred to as a device that converts electrical energy into a linear or circular motion. Hence, electric actuators are of two...

Exploring pneumatic actuators

Pneumatic actuators use pressurized air or gas as an energy or power source to produce rotary or linear motion. They are very reliable, efficient, and safe for use in an environment where electricity may cause a fire hazard. They have various industrial applications, which include the regular opening and closing of valves, pick and place handlers, and so on. A pneumatic actuator can also be referred to as a pneumatic cylinder or air cylinder.

In a pneumatic actuator, compressed air or pressurized gas enters a chamber, and the gas builds up pressure in contrast to the outside atmospheric pressure, which results in the motion of a device, which could be a piston or gear. The motion created by a pneumatic actuator can be linear or circular. Hence, a pneumatic actuator simply converts the energy in compressed air into a linear or circular motion.

Figure 3.16 shows a valve on the left side of the figure that can be operated manually and a valve on the right side...

Getting to know about hydraulic actuators

Hydraulic actuators use pressurized hydraulic fluid (that is, oil) as an energy source to produce rotary or linear motion for an application consisting of high force and ruggedness. A hydraulic actuator can also be referred to as a hydraulic cylinder. It converts hydraulic energy (that is, the energy of fluid) into motion. It also consists of a cylinder in which a piston connected to a piston rod moves back and forth by pumping hydraulic fluid into a port at one end of the piston or at the other end.

Similar to a pneumatic actuator, a hydraulic actuator has two types:

• Hydraulic linear actuator
• Hydraulic rotary actuator

The principle of operation of each type is similar to the ones explained about pneumatic actuators in the previous section of this chapter, only that hydraulic actuators utilize hydraulic fluid (that is, oil) unlike compressed air or gas used in pneumatic systems.

The following diagram shows a single-acting hydraulic linear actuator...

Summary

You have successfully completed this chapter of the book. Well done! With having reached the end of this chapter, you should now be able to explain actuators and the basic types available (electric actuators, pneumatic actuators, and hydraulic actuators).

Electric actuators use electricity, pneumatic actuators use compressed air, while hydraulic actuators use pressurized fluid (oil). They all perform actions through motion, which can either be linear or rotational. Some actuators are better suited for a particular application than others. For instance, a hydraulic actuator is useful for tasks requiring high force. It is good to have knowledge of all three types mentioned in this book. You might find any of the types in the industry you happen to find yourself working in as an automation engineer.

The topics touched on in this chapter are relevant for automation engineers and will help you to better understand the next chapter in this book, AC and DC Motors.