Pneumatic Air Cylinders

The piston moves as a result of an increase in internal pressure. The force produced by the piston is then transferred to an item through the piston rod. Pneumatic air cylinders can be used to clamp items together or block them from coming into contact with one another. Most notably, they are used in factories to move parts and perform other simple tasks.

Components of Pneumatic Air Cylinders

There are many components within a pneumatic air cylinder. We discuss a few in further detail below.

Pneumatic cylinder barrel: Essentially, the barrel houses and protects (most of, depending on design) the internal components- most notably the piston and piston rod.

Piston: The piston is the disc inside the pneumatic cylinder which serves as a movable partition which divides the chamber and reciprocates the back and forth movement in a straight line.

Piston rod: The piston rod is linked and controlled by the piston. It is connected to the machine elements or objects that require to be pushed or pulled.

Piston cushioning: This lowers the speed of the piston and rod assembly before it reaches the end cap. It also helps to reduce impact, noise, and vibration at the end of every stroke and enables the piston to move at higher velocities.

Piston static seal: This device ensures airtight sealing between the piston and the rod.

Piston seal: A piston seal ensures airtight sealing between piston and chamber.

Working Principle of Pneumatic Air Cylinder

As air continues to enter the cylinder from one side, the pressure inside increases. The piston moves in a certain direction as a result of an increase in internal pressure. The produced force is transferred to the item to be pushed by the piston rod. The specific motion needed, such as clamping or moving a load along a linear path, is then produced by a pneumatic actuator receiving the force from the compressed air through the piston (via the piston rod) inside the cylinder.

The final use for this energy may include operating a specific tool like a gripper, clamp, or a vacuum, or it could be applied to numerous other potential applications.

Types of Pneumatic Air Cylinders

Single-Acting Cylinders

Pressurized air enters a single port, in a single direction, in single-acting (single-action) cylinders. The piston is typically fitted with a load or a spring. After being cleaned and compressed, air enters the single port and forces the piston to extend in one direction, compressing the spring. After expelling air through the same port where it entered, the spring (or some external force) will retract the piston back to its initial position. Simply put, the spring will reverse the stroke that is forced forward inside the cylinder by the compressed air. A button can be used in a straightforward circuit to control a single-acting pneumatic actuator. By pressing this button, the piston rod is propelled outward by air.

There are two types of single-acting cylinders: pull or push cylinders. With a push cylinders, air enters to push the piston out of the cylinder. In a pull cylinder, air enters to pull the piston inside of the cylinder.

Advantages of Single-Acting Cylinders:

• They feature a simple design and are easy to install.
• Single-acting cylinders have a low initial cost.
• They are single-port so the air is only used in one direction. As a result, they operate more efficiently than a double-acting cylinder since less energy is consumed.

Double-Acting Cylinders

Double-acting cylinders move loads in both directions, and can extend and retract without the need of a spring. Instead of applying pressurized air into one port, double-acting cylinders have two ports where air can enter in and out. Double-acting pneumatic cylinders are highly utilized in industrial and robotics industries where they perform tasks such as door opening and closing. They can perform lifting and moving products off conveyor belts. Double-acting cylinders can also be used in medical applications, space programs and earth-moving equipment.

Advantages of Double-Acting Cylinders:

• They provide more control over movement.
• They are faster and stronger than single-acting cylinders.
• There is a broader design variation of double-acting cylinders.
• This design variation also lends itself to an increase in ISO- (International Organization for Standardization) standard compliance.

Disadvantages of Double-Acting Cylinders:

• Double-acting cylinders are more expensive to purchase and operate.
• Desired air-flow rates require more complicated calculations than with single-acting cylinders.

Applications of Pneumatic Air Cylinders

• Single-acting cylinders are used for simple applications such as factory automation settings, performing jobs such as materials handling and packaging operations. These cylinders are used for part and tool positioning, and, additionally, for helping with tasks such as clamping and punching.
• Double-acting cylinders are used for complex and heavy-load applications like “knifing” in the paper industry. When producing paper, huge coils of paper must be sliced into smaller rolls and this is achieved through double-acting pneumatic air cylinders. Paper-cutting machinery uses a double-acting cylinder that moves at the same speed as the paper to slice it on the fly, retract, and reposition for the next cut, where it remains in place until the next cutting spot arrives.
• Double-acting cylinders are used where high force is required in both directions and an example of this occurs regularly in foundries, where furnaces reach high temperatures. With safety being of the utmost importance, a double-acting cylinder makes sure these furnace doors stay closed, but can still be opened when necessary.