Actuator, also referred to as air cylinders or pneumatic cylinders, mechanical devices which use compressed air to move a load in a linear path. The most common type of pneumatic actuator includes a piston and rod moving inside a closed actuator, where the piston performs the desired movement. In pneumatic systems, air is used as the source of energy to operate and complete a given task, in this case, extending and retracting the piston inside a actuator.
Pneumatic Actuator is commonly applied as two types: single acting and double acting. The main design difference between both Actuators is the number of ports. Single acting Actuator has one port where pressurized air enters, while double acting Actuator use two ports to operate. This simple design difference distinguishes both actuator in terms of movement and speed. When choosing a Actuator, it is important to know the application of each device, their differences, advantages and disadvantages.
Single Acting Pneumatic Actuator, also referred to as spring return Pneumatic Actuator
If you are looking to utilize your machine in a linear motion and perform movements such as clamping, positioning and punching, then single acting Actuator might be your solution. How do they work? Single acting Actuator have one port where pressurized air enters in one direction. A spring, or a load, is usually fitted to the piston. Once air is cleaned and compressed it enters through the single port forcing the piston to extend in one direction compressing the spring. The spring (or another external force) will retract the piston back to its original position after releasing air through the same port where it originally entered. Simply put, the compressed air will force a forward stroke inside the actuator and the spring will return the stroke.
Advantages of Single Acting Pneumatic Actuator:
1. Simple design; easy to install
2. Low cost of initial purchase
3. Single port and small housing
4. Reduction in valve and piping cost compared to double acting pneumatic actuator
Disadvantages of Single Acting Pneumatic Actuator:
1. Compressed air requires proper preparation
2. Spring takes too much space and limits working area
3. Reduced thrust due to the opposing spring force
4. With prolonged spring usage, pistons strokes can become inconsistent
Double Acting Pneumatic Actuator
When looking for a device to move load in both directions, double acting pneumatic actuator is a useful application when your machine requires more than one movement. Unlike single acting air pneumatic actuator, double acting pneumatic actuator can extend and retract without the need of a spring. Instead of applying pressurized air into one port, double acting pneumatic actuator has two ports where air can enter in and out.
Air enters through one port moving the piston forward and then applies pressurized air into the other port retracting the piston back into the pneumatic actuator. Double acting pneumatic actuator is the most widely used pneumatic actuators compared to single acting pneumatic actuator given their ability to extend and retract within a shorter time period, thus, becoming more efficient and precise.
Double acting pneumatic pneumatic actuator are mostly used in industrial and robotics industries. They perform tasks such as opening / closing doors and lifting and moving merchandise off conveyor belts. Other uses include medical applications, earth-moving equipment and space programs.
Advantages of Double Acting pneumatic actuator:
1. More control over movement since pressurized air moves both ways
2. Faster, stronger and use less energy
3. Offer more design variation: stroke and bore sizes
4. Many double acting pneumatic actuator are ISO compliant as opposed to single pneumatic actuator
Disadvantages of Double Acting pneumatic actuator:
1. More costly than single pneumatic actuator
2. Requires bigger housing - if used as a feed actuator it needs to be coupled with another machine system
3. In certain situations, air consumption may be calculated at different rates
Single vs Double Acting Pneumatic Actuator: Which one should I choose?
Although both systems use compressed air as their main source of energy, their port design allows them to perform quite differently. Single acting pneumatic actuator is mainly used in industrial applications where force is needed in one direction, for example, ejecting parts / items off conveyor belts. Double acting pneumatic actuator, on the other hand, are widely recognized across many industries for being faster, stronger, and more efficient than single acting pneumatic actuator. Applications that require speed and force will need the help of double acting pneumatic actuator whereas light assembly work can be deployed by single acting pneumatic actuator.
