Pneumatic cylinders, also referred to as air cylinders, are devices that convert compressed air power into mechanical energy. This mechanical energy produces linear or rotary motion. In this way, the air cylinder functions as the actuator in the pneumatic system.
A pneumatic cylinder consists of a steel or stainless steel piston, a piston rod, a cylinder barrel and end covers. As compressed air moves into a cylinder, it pushes the piston along the length of the cylinder. Compressed air or a spring, located at the rod end of the cylinder, pushes the piston back. Valves control the flow of compressed air to the cylinder. The choices for cylinder housing styles include the following: tie-rod, smooth body, pancake, rectangular, multiple bore, stainless steel, rodless, compact, miniature/microcylinder, clean profile and twin-rod cylinder.
The two basic types of pneumatic cylinders, based on how they perform, are single acting and double acting. The single acting cylinder is able to perform an operating motion in only one direction. A single acting pneumatic cylinder has air pressure on one side of a piston flange, supplying force and motion, and a spring supplying the return force after pressure release.
Single acting cylinders require approximately half the amount of air used by a double acting cylinder for a single operating cycle. A double acting pneumatic cylinder has powered motion in two directions, with pressure on both sides. When a cylinder is pushed out in one direction, compressed air moves it back in the other direction.
Air lines running into both ends of the cylinder supply the compressed air. The flow of compressed air is controlled with valves for both single and double acting cylinders. Other types of cylinders include rotary cylinders, impact cylinders and multiple-position, or opposed-thrust, cylinders. Pneumatic systems are used to push, pull, lift and open/close doors in material handling and processing.
They can also hold, remove and position materials or pieces for manufacturing. Pneumatic systems can be connected with hoses, pipe or tubing without difficulty, producing a large amount of linear energy. Using pneumatic systems is economical and environmentally friendly, as air is inexpensive, plentiful and easily compressed and stored in tanks. Exhaust air can also be returned to the atmosphere.