Air Cylinders
Air cylinders, also known as compressed air pneumatic cylinders, serve as actuators in pneumatic component systems. An actuator is any device that delivers or transmits controlled energy in a reciprocating linear motion as part of a mechanical process. The energy produced by high-pressure compressed air is converted into kinetic energy, which then powers a machine motor. Unlike pneumatic systems that use air or gas, a hydraulic cylinder actuator operates with a fluid motor that relies on hydraulic power for mechanical function.
History of Air Cylinders
Pneumatic devices generate and utilize compressed air, with their origins tracing back to early smelters and blacksmiths who employed simple air compressors to shape metal and iron.
The first significant advancements in air compression came from physicist and engineer Otto von Guericke in the 17th century. In 1650, he invented the first air pump capable of creating a partial vacuum, using it to study air’s role in combustion and respiration. However, it wasn’t until 1829 that the first stage or compound air compressor was patented. This design operated through successive cylinders, significantly enhancing efficiency. In 1872, a major breakthrough was achieved with the introduction of water-jacketed cylinders, which used water jets to cool the cylinders, improving performance and reliability.
How an Air Cylinder Works
Air cylinders serve as actuators in pneumatic systems, where an actuator is any mechanism that delivers or transmits controlled energy as part of a mechanical process. Many industrial applications require an actuation method that is dependable, free of harmful chemicals, and available in multiple configurations to suit different operational needs.
Various air cylinder designs accommodate specific applications. A single-acting cylinder operates in one direction by introducing pressurized air on one side of the piston, causing movement. A spring on the opposite side supplies the return force once the pressurized air is released. Because of this design, single-acting cylinders consume approximately half the air required by a double-acting cylinder for a single operating cycle.
A double-acting pneumatic cylinder enables powered motion in both directions. When the cylinder extends in one direction, compressed air retracts it in the other, with air lines supplying pressurized air to both ends of the cylinder. Within these two primary configurations, numerous specialized variations exist, each designed to optimize performance for specific industrial applications.
Design of Pneumatic Air Cylinders
Every air cylinder consists of a piston, end covers, and a cylinder barrel with at least one air inlet. When compressed air enters the cylinder, it pushes the piston along its length, generating motion. The cylinder connects to a protruding rod or another structural component, which is then linked to the object requiring movement.
Pneumatic cylinders vary in size, design, and function, but they typically fall into three main categories: single-acting cylinders (SACs), double-acting cylinders (DACs), and specialized types. In all configurations, valves regulate the flow of compressed air to control movement.
SAC Design
Single-acting cylinders (SACs) operate with a single inlet for compressed air, moving the piston in one direction. A spring located behind the piston pushes it back when the compressed air is released. Because of this design, SACs require approximately half the air volume used by double-acting cylinders for a single operating cycle. An example of a single-acting cylinder is a rotary screw air compressor, which uses two interlocking helical rotors housed in a chamber. Air enters through an inlet valve and is drawn into the space between the rotors, where the screws reduce the air volume, increasing its pressure.
DAC Design
Double-acting cylinders (DACs) allow powered movement in both directions. They feature two inlets, one on each side of the piston, enabling compressed air to push the piston back and forth. This design provides more precise and consistent force application.
While SACs and DACs are the most common pneumatic cylinder types, many other specialized air cylinders are designed for specific functions.
Other Air Cylinder Designs
Cable cylinders feature an elongated housing with two rollers and a cable extending from one end of the cylinder to the other. The load-bearing yoke is suspended by the cable, and as the cable moves back and forth, it transfers motion to the attached load.
Rotary pneumatic cylinders offer a superior alternative to traditional linear air cylinders by enabling smooth, bidirectional circular movement. These compact components house precision-engineered impellers that rotate around a central axis, driven by controlled compressed air flow. Unlike conventional pneumatic actuators, rotary cylinders provide seamless clockwise and counterclockwise motion, high torque output, and precise rotational control, making them ideal for industrial applications requiring efficient and versatile circular motion.
Rodless cylinders are designed with a long barrel that includes a vertical slot, allowing the piston to connect to a load-bearing carriage. They transmit force using either mechanical or magnetic coupling, moving an attached body along the cylinder’s length. These cylinders come in various sizes and load-bearing capacities, ranging from small units used in electronics manufacturing to large-scale cylinders designed for heavy-duty industrial operations. The materials used in cylinder construction also depend on the application, with stainless steelcommonly chosen for high-load capacities and harsh environmental conditions.
Components of Air Cylinders
Carefully selected air cylinders can be invaluable assets, offering efficiency, environmental benefits, and a wide range of configurations to meet the needs of most industries. When choosing a cylinder, it is essential to consider its ability to move the greatest load at the lowest acceptable velocity while utilizing the minimum available pressure. Compared to hydraulic systems, air cylinders provide enhanced safety by minimizing the risks associated with gas and fluid leaks while maintaining reliable performance.
ISO 6432-compliant cylinders maintain standardized dimensions across different manufacturers, but not all air cylinder producers adhere to these standards. Because many industrial applications require extreme precision, every air cylinder must be chosen with care to ensure proper and safe operation.
Several optional components enhance cylinder performance and help prevent operational issues. These include cushions, bumpers, stop tubes, dual pistons, flow controls, position-sensing switches, and position feedback sensors. Cylinder mounting hardware—such as noses, blocks, pivots, and other structural supports—is selected based on the size, force, and function of the cylinder.
Common construction materials include stainless steel and brass, with nickel-plated brass offering superior corrosion resistance compared to standard brass.
Air cylinders are available in a wide range of sizes, from diameters as small as 2.5 mm to as large as 1,000 mm. As microtechnology continues to advance, compact cylinders, miniature air cylinders, and small air cylinders are becoming increasingly essential for manufacturers requiring precise, small-scale pneumatic actuation.
Applications for Air Cylinders
In various industrial applications, linear motion plays a crucial role in the operating process. One of the most cost-effective and straightforward methods to achieve linear motion is by using a pneumatic air cylinder. Air cylinders are widely utilized in industries such as food processing and packaging, metalworking, automotive manufacturing, mining, textile production, and many others.
Flow Control System Operation in an Air Cylinder
Many industrial process machines rely on compressed air as a source of energy, including air cylinders, or more specifically, pneumatic cylinders. Pneumatic actuators are also often used in industrial appliances to power manufacturing processes. Compressed air is a highly flammable and explosive gas that moves rapidly from a high-pressure chamber to a low-pressure atmosphere. The shifting of the air valve, release of gas through the valve, and movement of the cylinder piston and rod all occur quickly.
As a result, the speed of the piston, rod, and airflow is crucial to measure and control during the process. Fast-moving rods are difficult to measure directly, which is why air flow control systems are frequently incorporated into air cylinder designs. These systems are commonly installed in the air lines between the valve and the cylinder, as well as in the cylinder port and sometimes the exhaust port. However, placing the flow control system in the exhaust port is not always necessary.
When introducing an airflow controller system into a cylinder, it is important to consider the cylinder’s control reaction time, which largely depends on the distance between the flow control system and the cylinder.
Another method of controlling airflow is through the use of needle valves. These valves regulate the air entering and exiting the cylinder, often reducing the airflow significantly. However, this can cause issues with heat or energy transfer within your process equipment if airflow is restricted in either direction.
Cylinder flow control systems, which resemble needle valves, may include a needle bypass. This allows the air to pass through the needle and controls the airflow accordingly.
The free flow of compressed air through the cylinder’s flow control system ensures that the cylinder receives a full and proper supply of air. Proper installation of the system is critical to ensure that the outflow is also regulated to the desired level, which helps maintain the intended cylinder speed.
If a second airflow control system is required, it can perform the same function to regulate air movement.
Flow control systems regulate the airflow into and out of a cylinder port, providing smooth and controlled piston movement. The smoother the piston movement, the more precisely your process equipment will function. Without a flow control system, the piston would move uncontrollably at a high speed. When installed in the exhaust flow, the flow control system prevents unregulated piston movement, ensuring that it operates at a controlled and programmed rate. For proper function, it’s important to ensure that the flow control system is correctly installed in your compressed air unit.
Most cylinder flow control systems feature a schematic on the side showing the correct flow paths to ensure proper installation. Proper installation helps reduce waste and improves equipment performance.
Industrial air cylinders can be customized based on plant or application requirements by working with a manufacturer or supplier. Additionally, liquid and solid carbon dioxide in various cylinders, vessels, and containers can also be customized to fit specific application needs.
Types of Air Cylinders
Brass Cylinders
Pneumatic actuators made from specific copper alloys that are resistant to corrosion and wear, suitable for use in various harsh industrial environments.
Cable Cylinders
Pneumatic devices that utilize pressure differentials to convert compressed air energy into mechanical energy, facilitating the lateral movement of a cable or wire and the loads attached to it.
Clean Profile Cylinders
Flat barrels with rounded edges and T-slots for sensors along the entire length of the barrel on three sides. These are used in applications requiring ease of cleaning and good hygiene, as the clean, square line design prevents the accumulation of dust and dirt.
Compact Cylinders
Also known as “short stroke cylinders,” these cylinders are small in size compared to standard cushioned cylinders. They are ideal for applications with limited space, allowing for short distance movements and locking in confined spaces.
Compressed Air Cylinders
Convert compressed air power into mechanical power.
Double Acting Cylinders
Have air lines that supply pressure to both ends of the cylinder, enabling motion in two directions. The flow of compressed air is controlled by valves.
Double Rod Cylinders
Feature a piston with a rod extending from both ends of the cylinder.
High-Pressure Air Cylinders
The most powerful type of compressed air unit, designed for extensive tasks with a compact, efficient structure.
Miniature Air Cylinders
Also called "microcylinders," these small, rectangular, single-acting air cylinders have springs housed inside enlarged piston rods. They are easy to install and offer versatility with interchangeable mounting brackets.
Multiple Bore Cylinders
Contain two or more pistons and boxes stacked in the same cylinder.
Multiple-Position Cylinders
Double-acting cylinders that provide three or more end positions, unlike the typical two provided by standard double-acting cylinders.
Non-Rotating Cylinders
Cylinders in which the piston rod, ram, or plunger and the cylinder housing remain fixed, preventing rotation.
Pancake Cylinders
Feature shorter lengths and larger diameters compared to other cylinders.
Pneumatic Cylinders
Comprise a piston, upper and lower ports, and an expansion chamber.
Reverse Single Acting Air Cylinders
Similar to single-acting cylinders, but with a port located at the opposite end to provide power on the retraction (pull) stroke.
Rectangular Cylinders
Encased in a rectangular, box-shaped frame.
Rodless Cylinders
Have a barrel with a longitudinal slot that connects the piston to the mounting carriage. A hardened band pneumatically seals the cylinder, preventing contamination while allowing the carriage to move.
Rotary Cylinders
Pneumatic actuators that convert compressed air energy into mechanical energy for rotational movement.
Use air pressure to move the piston in one direction, with a spring providing the return force after pressure release. They require less compressed air than double-acting cylinders for a single operating motion.
Small Air Cylinders
Compact pneumatic actuators designed to maximize productivity in limited space. Smooth body cylinders have a body that encases the piston.
Stainless Steel Cylinders
Ideal for harsh environments requiring rigorous cleaning for hygienic reasons or exposure to corrosive forces. They are typically considered "throwaway" cylinders, as they are irreparable but cheaper than other types.
Tandem Cylinders
Comprise two or more cylinders with linked piston assemblies.
Telescoping Air Cylinders
These cylinders work in both single and double-action modes, offering adaptability for specific manufacturing applications. They tend to be more expensive due to their specialized nature.
Tie-Rod Cylinders
Held together with exterior tie rods, usually in a rectangular bolt pattern.
Twin Rod Cylinders
Feature side-by-side twin cylinders in one body with two piston rods connected to a mounting plate, ensuring precise guiding and doubling the force of a standard cylinder of the same height.
Proper Care for Air Cylinders
Proper care is essential for air cylinders since they do not have the internal lubrication found in oil-lubricated cylinders. Some condensation will form when the compressor is in use, and it’s important to check for corrosion on non-stainless-steel components. If left unchecked, this corrosion can lead to issues during operation, though it may go unnoticed while the cylinder is in use. However, when the cylinder is idle for extended periods, the corrosion can become problematic over time.
Here are a few key points to keep in mind when maintaining air cylinders:
- Air compressors must be equipped with a properly fitted water safety device. If one is not available, turn off the water supply a few minutes before stopping the air compressor, then allow the compressor to run unloaded to let any condensation drain out.
- Air compressor cylinders should be operated for at least 30 minutes every week to prevent extended periods of idleness.
- Monthly cleaning is necessary for unloading pistons in the suction valve cover. Applying a thin layer of grease or silicone can help prevent sticking.
- It is crucial to keep the air cleaner element clean at all times. Cleaning should be done every 500 working hours, from the inside out.
Things to Consider When Purchasing an Air Cylinder
Air cylinders, also known as pneumatic cylinders, are industrial devices that utilize mechanical engineering principles to generate force and movement. The force and movement are driven by high-pressure compressed air, which serves as the source of energy regulating the performance and productivity of process equipment. The energy created by the compressed air is converted into kinetic energy, which powers a machine motor.
To achieve optimal manufacturing efficiency and process performance, it’s crucial to select the right air cylinder for your specific production needs. Choosing the ideal air cylinder requires evaluating several important factors, including selecting the right cylinder bore size to maximize thrust, customizing the mounting style for smooth operation, determining the appropriate cylinder stroke for improved performance, and balancing speed and precision for more efficient production. Careful consideration of these elements can enhance your manufacturing process, increase productivity, and ensure quality results in applications like pneumatic automation, industrial machinery, and precision manufacturing. This strategic approach helps identify the perfect high-performance air cylinders tailored to your requirements, whether you're prioritizing speed, precision, or cost-effective solutions for industrial automation.
Air Cylinder Machine Weight
When selecting an air cylinder for your process equipment, it is essential to consider the weight of the machine that will use the air cylinder. The machine relies on the energy produced by the cylinder, and its performance is directly influenced by the pressure generated by the compressed air. Therefore, it's important to factor in the weight of the motor, usually the starter motor, when choosing the appropriate air cylinder. A good rule of thumb is to select a compression cylinder rated for a machine that is 25% heavier than yours. This safety margin is commonly used in most manufacturing operations.
Cylinder Rotation Diameter
If you need to move an object four inches, the ideal size of the cylinder's rod should be at least four inches. However, you may choose a larger cylinder size depending on your requirements. The size of the object and the rod or piston within the cylinder should also be considered when making this decision.
Correct Cylinder Installation
Before selecting an air cylinder, check with your supplier to see if they offer installation services. Proper installation is crucial to ensure the safety and efficiency of the system. The installation should be done based on the cylinder's size and type. Following the correct installation procedures is important for the proper functioning of the application. Air cylinders come with various design options that simplify installation, including rod-cap threads, rear-cap threads, rear tangs, mounts, and threaded holes for bolting. Ensuring proper installation allows the cylinder to bear the load that the compressed air is attempting to move.
Cylinder Type
Air cylinders come in various types, including reusable cylinders, non-reusable or repairable cylinders, NFPA cylinders (approved according to government standards), rod-based cylinders, and metal cylinders made from materials like steel or aluminum. When deciding which type of cylinder is suitable for your application, consider the operating conditions and the type of application. You can always consult with your supplier or process engineers for guidance on choosing the right type of cylinder for your needs.
Air Cylinder Manufacturers and Suppliers
IQS Directory offers a comprehensive list of air cylinder manufacturers and suppliers. You can find companies that specialize in designing, engineering, and manufacturing air cylinders tailored to your specifications. Explore our website to discover top air cylinder manufacturers, complete with rollover ads and detailed product descriptions.
Easily connect with air cylinder companies using our convenient request for quote form. We provide company profiles, website links, locations, phone numbers, product videos, and detailed product information for your convenience.
Stay informed with product news articles and read reviews. When searching for a reliable air cylinder manufacturer for all types of air cylinders, IQS Directory is your go-to source.
Air Cylinder Terms
Actuator
A device that converts fluid power into mechanical power. An actuator may be a cylinder or a fluid motor.
Air Consumption
The amount of compressed air that is consumed by a pneumatic cylinder. The energy of the air is converted into power output and exhausted into the atmosphere during the piston stroke reversal.
Air Compressor
A device used in a pneumatic power system to supply the compressed air.
Bellows
A circumferentially corrugated cylinder that is flexible and thin-walled and may have integral ends that axially contract or expand when under changing pressure.
Bore
The inside diameter of the cylinder tube.
Bubble Tight
A term referring to a tightly closing valve seat that prevents the leakage of visible gas bubbles.
Clearance
On the working side of the piston, the maximum volume of the cylinder from which the piston displacement volume per stroke is subtracted. Typically, clearance is expressed as a percentage of the displacement volume.
Clevis
A cylinder mounting device.
Compressed Air
Air that is at any level of pressure greater than the prevailing atmospheric pressure.
Crosshead Assembly
The connecting assembly used to translate circular motion to linear motion from the crankcase and connecting rod to the cylinder head and piston rod.
Cushion Cylinder
A device in a cylinder that enables the control of movement by restricting the flow at the outlet, stopping the movement of the piston rod.
Cylinder
Also referred to as a “linear motor,” it is a device that converts pneumatic power into linear (in a line) or reciprocating (back-and-forth) motion.
Cylinder Thrust
The driving force (i.e., the piston power) generated in the cylinder, which is a function of the piston diameter, the working air pressure, and resistance caused by friction.
Directional Control Valve
A valve that controls the flow of air in a particular direction.
Drag
A situation in which the valve remains partially open after popping until the pressure further decreases.
Filter
A device through which air is passed in order to separate suspended contaminants. The life of cylinders and valves is lengthened by using filters.
Fluid
A liquid or gas.
Fluid Power
Power conveyed and maintained by the use of a pressurized fluid.
Foot
A mounting device for cylinders.
Gag
A device that, when attached to a safety or safety relief valve, prohibits its opening at the set pressure.
Linear Actuators
A device that creates mechanical force in a linear manner.
N.C. (Normally Closed)
A designation describing the position of a valve when it is resting (non-activated).
N.O. (Normally Open)
A designation describing the resting position (non-activated) of a valve.
Piston
The sliding piece that is put into motion by pneumatic pressure. Typically, pistons consist of a short cylinder fitted inside a cylindrical tube in which it moves in and out.
Piston Velocity
Determined by opposing forces, operating pressure, inside diameter, length of air line between control valve and cylinder, and size of control valve. The piston velocity may also be affected by the installation of any quick-exhaust or throttle valve.
Pneumatic System
The use of a gas, usually air, to transmit, convert or store power.
Port
The external or internal terminus of the valve on an air cylinder.
Power Factor
The relationship between the surface area of a piston and air pressure of an air cylinder.
PSIA (Pounds Per Square Inch, Absolute)
The sum of gauge and atmospheric pressures, which will vary with altitude.
Regulator
A device that provides control of the operating pressure of the compressed air system. Regulators allow working pressure of the system to be adjusted from the minimum to the maximum at the prop.
Reservoir
A storage area for air that, when located near the prop, prevents air starvation.
Solenoid
A coil of wire, usually in cylindrical form, that is used as a switch or control for the valve of an air cylinder. When solenoids carry a current, they act like a magnet, drawing a moveable core into the coil as the current flows.
Valve
A device that controls the flow of air in an air cylinder.
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