How does a pneumatic system work simple?

What is Pneumatics?

Pneumatics is how air pressure powers and moves something. Essentially, pneumatics puts compressed air to practical use by moving applications like the tools and machinery used in the engineering, manufacturing and construction industries.

Also known as...

Using energy made from the controlled release of compressed air and turning it into movement. 

How does pneumatics work?

Pneumatics is a simple and reliable way to make things move, just by using clean, dry air. Pneumatic systems use this compressed air to create mechanical motion and power applications to ‘do work’ in factory automation systems. Pneumatics are seen in a range of other applications too, from fairground rides and trucks, medical applications and food preparation through to air tools and blow molding.

Pneumatics makes use of an air compressor to reduce the volume of the air in order to increase its pressure. This then moves through a filter into pneumatic tubing, where it’s controlled by valves before reaching an actuator which does the work at the end of the process.  That could be a cylinder, or a device that performs a function, for example, lifting, moving or gripping.

How do I select a pneumatics system?

Pneumatic systems can be used as an alternative to electric actuators and motors by driving linear and rotary motion applications. It is generally used with smaller loads as pneumatic systems produce less force than hydraulic systems and as air is easy to compress, pneumatics can absorb excessive shock.

As manufacturing makes advances, and with developments in seals such as corrosion resistance,  the environments in which pneumatic systems can be used has increased, with pneumatics comparable to some electric automated systems. Pneumatics is such a versatile way to power tools and machinery, it remains an important technology in a number of sectors. 

To select a pneumatics system for industrial applications, consider what you require in terms of your operating sequence. Pneumatics works in linear and rotary motion and is a simple way to actuate an output motion or apply a force.

When choosing a pneumatics system, you must consider the pressure and flow requirements for the best possible performance. If incorrect components are used, the pneumatics system may not perform properly.

Flow and pressure are different, and should be controlled individually. The regulation of pressure in compressed air systems does not precisely control flow, which could lead to an increase in energy costs.

Whereas pressure is a force applied across a given area, the flow is the volume of compressed air moved in a given time. Greater pressure over a small area can be the same as lower pressure over a larger area. Flow control works by restricting the orifice through which air can flow – as it closes, less air can flow, at a given pressure, in a given time.

The cost of maintaining pneumatics and pneumatics systems is generally low, but care should be taken to monitor leaks and corrosion. Applying a filtration system and monitoring the air supply will also ensure the pneumatics system works as it should.

Types of pneumatics

Vacuum devices are an example of pneumatics, and are often used in ‘pick and place’ systems such as vacuum cups to handle delicate items like glass, or moving or holding products in position while other work is carried out, such as cutting or crimping.  

Typical applications of pneumatics

Pneumatics is prevalent in commercial vehicles, ranging from usage in cab and chassis through to engines;  the energy sector, including the oil & gas and power generation industries, and food & beverage where pneumatics is present in everything from blow molding bottles through to process automation and packaging. Pneumatics are also at work in life sciences, such as medical equipment, and the global rail industry where it’s used in applications like door control and suspension.

Pneumatics are also used across manufacturing to power factory automation systems and is typically seen in sectors like materials handling and packaging. As it turns the energy from compressed air into a linear or rotary movement in order to carry out specific tasks, pneumatics can be used to perform ‘pick and place’ tasks like holding and positioning parts by clamping or gripping, or moving a tool that lifts, presses, cuts, sorts or stacks.

Pneumatics is also used in certain types of factory machinery, such as paint-sprayers. It’s also commonly seen (and heard) in power tools like road drills, where compressed air is channeled through a pipe to pump a metal chisel into the pavement.

Do I need anything else to make a pneumatic system work?

As pneumatics uses energy stored in compressed air to perform tasks or carry out work, an air supply is required.  The quality of compressed air used should be high enough to guarantee efficient operation. Air preparation in pneumatics is therefore key and moisture, unwanted dust particles and oils have to be drawn out otherwise they can congeal or corrode certain components such as valves and seals. Filtration is used in pneumatics in order to remove moisture droplets and solid particles, as well as aftercoolers and drying equipment. The air supply must be filtered and monitored constantly in order to keep the system operating efficiently and the various components working properly.

In machine automation a pneumatic system provides a simple and cost-effective means to move, clamp, rotate, grind and screw.

A pneumatic system is a collection of interconnected components using compressed air to do work for automated equipment. Examples can be found in industrial manufacturing, a home garage or a dentist office. This work is produced in the form of linear or rotary motion. The compressed air or pressurized gas is usually filtered and dried to protect the cylinders, actuators, tools and bladders performing the work. Some applications require a lubrication device that adds an oil mist to the closed pressurized system.

Pneumatics is an application of fluid power—in this case the use of a gaseous media under pressure to generate, transmit and control power; typically using compressed gas such as air at a pressure of 60 to 120 pounds per square inch (PSI). Hydraulics is another form of fluid power, which uses a liquid media such as oil but at a much higher pressure with a typical range of 800 to 5000 PSI.

A big reason pneumatics are used is due to simplicity. With little experience, on-off control of machines and equipment can be designed and assembled quickly using pneumatic components such as valves and cylinders. With proper air preparation, pneumatics systems are also reliable, providing a long service life with little maintenance needed.

Be Efficient

While a design using pneumatics is simple, there are some techniques to help make a better, more efficient system. It’s important to eliminate leaks. Any signs of an air leak should be addressed immediately. Related to this is tube length. Shorter tube lengths minimize system volume that must be pressurized and wasted each cycle, in turn minimizing air use. A valve mounted directly to a cylinder is an extreme example, providing the quickest pneumatic system response as well.

When selecting pneumatic components, be sure to not oversize them. This includes cylinders, valves, hose and tubes. Use online pneumatic air consumption tools to assist with this. Basically, determine the force needed to perform the work, calculating cylinder bore size based on this and the pressure available. With the pressure and cylinder bore known, calculate the valve air volume in cubic feet per minute (CFM), using the pressure, bore, stroke length and time for stroke.

While the cylinder is performing work, during clamping for example, a suitable design pressure of 60 to 80 PSI is common. However, retracting the clamps at a lower pressure uses less energy, so consider using a low pressure return or homing pressure.

Pneumatic System Components

There are many components connected to create a complete pneumatic system. Nearly all pneumatics systems consist of these items:

• A method of generating compressed air to power the system. This is usually a plant air compressor and often includes pressure tanks, for reserve air, and distribution piping to machines and equipment.

• A method of conditioning the compressed air, both at the compressor and locally, at the machine. All pneumatic motion requires clean and dry air with enough flow and pressure to perform the work. The process of filtering, regulating and lubricating compressed air is known as air preparation, or air prep. Manufacturing plants include air prep at centralized compressors, and additional air prep is beneficial at each machine’s point- of-use. This includes a manual shutoff, a filter to remove dirt, oil and water as needed, a regulator to control the system pressure, and possibly a lubricator to lubricate the air when needed for air tools or similar. A “soft start / exhaust dump” valve is also often included for operator safety to shut off upstream pressure and quickly relieve motion causing downstream pressure (pneumatic energy) when de-energized during a safety event.

• A method of controlling the directional flow of air. These are typically one or more types of valves. A good choice in machine control would be a 5-way, 3-position, center-exhaust valve where the center off position dumps air from both sides of the cylinder when an emergency stop is pressed, and power is removed. This valve typically operates using two 24 VDC solenoids. Energizing individual solenoids extends or retracts its corresponding cylinder.

• One or more air-driven work devices. These can be linear or rotary actuators (cylinders), grippers, motors, air nozzles, etc.

• A collection or fittings and piping to connect all the components of a pneumatic system. These include rigid pipe and tubing or flexible tubing or hoses. Most cylinders include flow controls to both ports, to limit the cylinder speed by restricting air as it leaves the cylinder.

Pneumatic systems are common in industrial machine automation. Be sure to supply, prepare and distribute the air properly. When correctly selected, assembled and installed, pneumatic devices and actuators will have a long, efficient life with limited maintenance required.