Have you ever considered how all those pneumatic cylinders are interconnected within industries such as manufacturing or robotics? In this article, you will discover the interesting features that distinguish the two types of pneumatic cylinders, the single-acting and the double-acting.

Get acquainted with the various internal workings of these mechanisms, their distinctive roles, and how gaining a certain degree of knowledge about them can help improve your work and increase efficiency in other sectors.

FSDA Double Action/Single Action Compact Cylinders

1) Working Principle: Single Acting Vs. Double Acting Cylinder

i) Single Acting Cylinder Working Principle

“As the name suggests, a single-acting cylinder only has a power stroke in a single direction ( extension ), while the retraction is done by a spring.”

A single-acting cylinder consists of the following components:

• Rod: A solid pipe that extends outside the cylinder.
• Air Ports: Holes to let air inside and outside the cylinder.
• Cylinder Body: A hollow body that contains everything.
• Spring: A helical element that exerts a force on the piston when air is vented.
• Piston: A circular disk that blocks the air and turns air pressure into linear motion.

➔ Working Mechanism: Single Acting Cylinder

Step 1) Air Intake: As the system is turned on, compressed air enters the cylinder through the inlet port, filling one side of the piston.

Step 2) Piston Movement: Air pressure coming through causes the piston to shift and the rod to move outward from the cylinder.

Step 3) Exhaust and Return: Air is allowed to flow out through the exhaust port. So, the spring on the other end of the piston pushes it back to its original non-extended positon.

 

ii) Double Acting Cylinder Working Principle

“As the name suggests, in an acting cylinder, there is a power stroke on the double sides ( extension & retraction ).”

There is no spring present as in an acting cylinder, and all the work is done by compressed air pressure. The components of an acting cylinder are;

• Cylinder Body: This is the hollow tube that holds all the other components together.
• Piston: This is a cylindrical disk which reciprocates within the cylinder.
• Rod: This is an elongated solid pipe linked to the piston, which extends beyond the cylinder.
• Air Ports: These are two holes that enable air to come and go in both directions, providing motion.

View More: What Is a Double-Acting Air Cylinder

➔ Working Mechanism: Double Acting Cylinder

Step 1) Air Supply: When you activate the system, the compressed air is send to the extension side inlet port, thus filling one side of the piston.

Step 2) Piston Action: This air pressure acts on the piston at the extension side end, causing the rod to be extended in that direction.

Step 3) Change of Direction and Return Stroke: When you change the airflow to the other port, the air goes to the retraction side end of the cylinder, builds pressure there, and pushes the piston & rod back to its original resting position.

2) Size

Single-acting cylinders: The design and construction of single-acting cylinders are less complex than those of double-acting cylinders, and their size is definitely simpler. The configuration with only one air-port and the use of a return spring or external force for retraction make these lightweight and most suitable for space-constrained installations.

Double-acting cylinder: The size of a double-acting cylinder usually increases because it has two operational airports and additional seals that allow air actuation in either direction. This makes it bigger and weightier, assuring versatility and controlled movement in both extension and retraction.

3) Speed

Single-acting cylinders tend to run for slower cycles since spring or weight needs to be used to bring it back. The force of the spring or the weight of the load can determine the speed of the return movement, hence affecting the overall speed.

Double-acting cylinders work faster as both sides of the piston can be pushed against by air pressure. One side is covered in air which forces the piston out, and once the air is switched to the other side the piston is able to go back which creates faster piston movements increasing the speed of every entire cycle.

4) Force Strength

Single-acting cylinders are usually weaker since a force is countered by the spring on the extension stroke. Moreover, since the retraction stroke is only dependent on a spring, the force produced during this movement is also limited.

In double-acting cylinders, however, springs are absent – hence, the extension stroke is completely unopposed. Furthermore, the retraction stroke depends on air pressure, enabling a great deal of adjustable and strong force.

5) Load Capacity

Single Acting Cylinder: Most often, single-acting cylinders possess a low load bearing capacity which ranges between 10 to 500 pounds based on its size and the pressure it is in. One needs to understand that since they depend on an air pressure on one side and a spring for retraction, their lifting capacity cannot be considered sufficient for heavy duty applications.

Double-acting cylinders can withstand a colossal load ranging from above 1000 pounds. This is due to the fact that force can be applied on both sides of the piston, which proves to be excellent suitability for tougher tasks drowning in power.

6) Air Consumption

Single-acting cylinders are air consumption efficient, requiring 30 percent less compressed air than double-acting cylinders. This is striking as they need air in extension stroke, thus helping keep operational costs low.

Double acting cylinders tend to consume more air than single acting. Due to the requirement of compressed air for both extension and retraction they sometimes consume up to fifty percent more air, thus resulting into a minor rise in your air supply expenses.

7) Dependence on Climate

Single-Acting Cylinder: Compared to double-acting cylinders, single-acting cylinders can be susceptible to temperature changes. For instance, a shift in the temperature could result in the spring hardening and impacting the speed & strength of the return stroke. This may be a factor if you operate in areas characterized by extreme weather changes.

Double-acting cylinders are usually not that sensitive to temperature changes. Since they do not have a spring in them ( they only rely on air pressure ), temperature variations have less of an impact on their functioning, improving performance consistency.

8) Maintenance

Single-Acting Cylinder: While using them, you would have surely noticed that single-acting cylinders have lower servicing needs due to their simple design & fewer parts. Just supervise the spring since it may deteriorate due to use, particularly after approximately 1,000 cycles.

Double-acting cylinders may require a little more servicing owing to more seals and air-ports. However, a simple regular inspection could maintain their performance. It is advisable to inspect them after every few hundred cycles to monitor their health status.

9) Age

A single-acting cylinder will usually deplete between 1500 and 3000 strokes, considering the wear and tear of the spring. If you frequently use the system, it might not last as long as you expect.

Double-Acting Cylinder: On the other hand, most double-acting cylinders do seem to last longer as there have been reports of them lasting around 5000 strokes or more. They have fewer moving parts and no spring as well; therefore, they are stronger which means less worrying for you when undertaking the tough tasks.

10) Price

Single-acting cylinders are relatively less expensive. They are less costly due to fewer materials used in their making and less complexity during the manufacturing process. Because they are cheap and their functions are quite simple, these cylinders are suitable for applications that do not require extra features.

Double-acting cylinders may be more expensive in terms of initial cost, but before disregarding them, think of these as investments. They are more expensive because of their intricate design and additional parts, which enable them to lift greater mass and offer more applications. In the long run, their high performance, as well as their durability, can bring down operational costs, which is beneficial, especially for demanding applications.

11) Applications

Single Acting Cylinder

Double Acting Cylinder

Clamping: Holds workpieces in place during machining or assembly. Pressing: Compresses items in packaging applications.  Lifting: Used in small lifts or jacks where repositioning is infrequent.  Ejecting: Used in mold applications to eject parts after formation.  Agricultural Equipment: Operates simple actuators in devices like seeders or planters.  Door Mechanisms: Utilized automatic door openers to push doors open.  Safety Devices: Acts as a lock or safety mechanism in various equipment.

Automotive Manufacturing: Moves heavy parts or machinery effectively.  Material Handling: Pushes, pulls, and repositions items in conveyor systems. Robotics and Automation: Provides precise movements in robotic arms and automated assembly lines.  Construction Equipment: Used in heavy machinery like excavators and bulldozers for lifting and tilting.  Packaging Machinery: Drives various packaging processes, including filling, sealing, and cutting.  CNC Machines: Controls the movement of tools for precision machining operations.  Beverage and Food Processing: Automates processes like bottling, canning, and sorting of products.  Textile and Printing Industries: Used to feed materials into machines and control fabric tension.

➔ Conclusion

In summary, knowing the key differences between a single and double-acting pneumatic cylinder will definitely benefit your project. Simplicity or force: every application needs the right cylinder to work. Such dependable pneumatic cylinders can be bought at FOYE; with our quality and performance integration and rich experience across the sector, you will also be pleased with our commitment to serving you.