Pneumatic refers to the use of compressed air in machine systems or when using tools. While the hydraulics use liquids during mechanical work, the pneumatics use the ambient air. This is compressed by means of the corresponding components pneumatic cylinder and pneumatic motor. The use of this drive technology is selected when high flow velocities of up to 300 m / min at low forces are required. Compared with environmental influences, the compressed air is insensitive, which is why pneumatic systems are mainly used in areas with an explosion hazard, in corrosive or radiation-exposed areas.
For high speeds at lower forces, the pneumatic drive technology is ideal. Because their fuel is gaseous and thus compressible. It is available as ambient air constantly and without restriction. Likewise, in the case of pneumatics, no return of the air, after actuation of the working member, is necessary. In contrast to hydraulics, where a closed circuit is required.
Another advantage of pneumatics over hydraulics is the higher flow rate of the air. This is at 10-15 m / s. As a result, cylinder outward speeds of up to 300 m / min can be achieved in pneumatics; in hydraulics they are limited to approx. 30 – 60 m / min.
Pneumatic circuits are comparable in their spectrum with the possibilities of electronics and are extremely insensitive to environmental influences. So strong temperature fluctuations, shock loads, vibrations and sometimes even dirt do not affect the functionality of the pneumatics. They can also be used in a corrosive atmosphere as well as in radiation-exposed areas. Pneumatic systems are also suitable for use in potentially explosive atmospheres, since the working medium air in most cases does not contribute to increasing the risk.
Accordingly, the technology of pneumatics is widespread: pneumatics, no matter whether pneumatic brakes are used in railway technology, pneumatically driven tools or equipment in conveying and positioning technology.
compressibility of air, however, also has disadvantages. It has the
consequence that signal transmissions are limited with pneumatic systems
to about 200 m distance.
The speed of signal transmission is limited by the speed of sound. This creates clear disadvantages compared to electronic systems.
The energy density is much lower in pneumatics with a maximum of 12 bar than in hydraulic systems. While in pneumatics it is possible to work with pressures of a maximum of 12 bar, hydraulic pressures between 30 and 315 bar are common, and in special applications (usually clamping operations) can reach up to 700 bar.
controls essentially consist of a control system and a drive or working
part. In the control part mechanical, electrical or pneumatic signals
are registered and processed. The output signals from the control part
are decisive for the behavior of the drive members, which generally
consist of compressed air cylinders or compressed air motors.
Drive links (cylinders and motors)
Pneumatic cylinders and pneumatic motors are the two pneumatic components that transform pneumatic into mechanical energy. They are also referred to as working members and thus represent the link between the pneumatics and the working machine.
Cylinder for linear movements (eg for clamping),
Cylinder with gear for swivel movements and
Air motors for rotating movements.
In control technology mainly linear actuators are used in the form of cylinders and z. B. used for clamping and feeding of workpieces in machining centers or for closure of packaging.
Control system (valves)
In pneumatics valves are used as actuators, which take over the control of the working members.
The following valve types are available:
Flow valves and
Special valves (eg proportional valves).