What is a cylinder or pneumatic actuator and how it works
Pneumatic cylinders, also known as pneumatic actuators, are used to provide movement & force linear or rotating to systems, machines and automated processes, for example in industrial applications.
Pneumatic cylinders/actuators work when the compressed air is forced into the cylinder/actuator itself in order to move a piston housed inside it. The “work” is performed by a mechanism connected to the piston, which converts the energy created into a practical use, for example a system for “pick & place” in factory automation.
Pneumatic cylinders and actuators are an easy way to gain strength and generate accurate linear and/or rotary movement and they can be used in harsh environments, even in extreme temperatures. Light and requiring little maintenance, they generally produce less force and a lower speed than hydraulic or electrical systems, but they remain an economically advantageous alternative.
Waircom offers a range of “standard” or “special” actuators and cylinders according to customer needs or produced according to widely adopted or international standards such as ISO.
How do pneumatic cylinders and pneumatic actuators work?
The key components of a pneumatic actuator include end-caps, a piston, a rod, a scraping seal, a barrel, a guide and sealing gaskets.
Pneumatic systems use compressed air to create rotary or linear motion and power applications that “work”. Pneumatic actuator will use compressed air to act on a piston inside the cylinder in order to create the required movement, for example tightening, or to move a load along a linear path. Final application can be as varied as a specific device such as a gripper or a clamp for a suction cup used to handle the glass.
A single-acting pneumatic cylinder or actuator has an “inlet”, in which air enters and then pushes the piston in one direction. The piston returns to its original position by a spring. These pneumatic cylinders have a limited stroke, so they are useful for slower operations. They also use less air so they are optimal for lower operating costs.
A double acting pneumatic actuator or cylinder has two holes which allow pressure to be applied for movement of the piston in the opposite direction than the one created by the first outlet.
Generally, larger is the cylinder hole and greater is the output in terms of strength.
How to select a pneumatic cylinder or a pneumatic actuator?
Type and characteristics of the actuator you need are dictated by the application you will use, cylinders or actuators are available in a range that varies from 8 mm to 320 mm bore, and they perform different functions depending on what is required. They are single-acting or double-acting, through or opposite rod, rotating or rodless…
Key factors to choose a pneumatic cylinder or actuator are:
- Type of movement: needed actuator or pneumatic cylinder depends on whether a rotary or linear movement is required.
- Pressure and flow requirements: you have to consider what you want by the pneumatic actuator or cylinder. This also covers other necessary components – if they are incorrectly sized, they can affect their performance.
- Environment: thanks to developments in corrosion resistance, pneumatic cylinders and actuators can be used at extreme temperatures. Actuators or cylinders are also available in Stainless steel version.
- Single-acting or double-acting: the actuators or pneumatic cylinders generally fall into one of these two categories depending on the type of application, force or required movement, size of the work and expected accuracy or control. Generally, an actuator or pneumatic cylinder will house a piston and a rod inside it.
- Application-dependent type: different types of actuators or pneumatic cylinders are available, including rodless cylinders, round cylinders and compact cylinders.
Tipi di cilindri pneumatici o attuatori pneumatici
Sono disponibili diversi tipi di cilindri pneumatici e attuatori, a seconda dell’applicazione richiesta. Possono essere a semplice effetto o a doppio effetto. Ecco alcuni esempi dei tipi di cilindri pneumatici e attuatori disponibili:
Cilindri ISO 15552 – Serie XT, Serie X e Serie XL Ø32÷320, il cilindro più comunemente utilizzato nell’automazione industriale e ad alte prestazioni, di lunga durata e in grado di funzionare anche a temperature elevate.
Cilindri a forma tonda ISO 6432 – Serie U e Serie P Ø8÷63: ideali per impieghi più leggeri e in applicazioni a forza minore.
Cilindri compatti ISO 21287 e AFNOR – Serie BX e Serie BU Ø25÷100: adatti alle macchine in cui lo spazio è un fattore determinante.
Attuatori rotanti Serie WR e Serie RX – Ø32:125: l’attuatore rotante fornisce un movimento angolare o rotatorio ed è disponibile nella versione rotativa a cremagliera.
Cilindri senza stelo – Serie Z Ø18÷63: questo cilindro lineare a doppio effetto è leggero e resistente.
Attuatori lineari in acciaio inossidabile: per l’uso in ambienti altamente corrosivi, come quelli dell’industria alimentare o farmaceutica, gli attuatori lineari ISO in acciaio inossidabile sono conformi alla norma ISO 6432, ISO 15552, ISO 21287
Cilindri tondi avvitati con accessori integrati – Serie HB Ø20÷100 Questi cilindri si caratterizzano dagli altri in quanto si presentano con gli accessori integrati nelle testate di conseguenza risultano più economici.
Types of pneumatic cylinders or pneumatic actuators
Different types of pneumatic cylinders and actuators are available, depending on requested application. They can be single-acting or double-acting. Here some examples of pneumatic cylinders and actuators available:
Cylinders to ISO 15552 standard – “XT” series, “X” series and “XL” series Ø32 ÷ 320, the most commonly used cylinder in industrial automation and high performance, long lasting and capable to operate even at high temperatures.
Round shaped cylinders to ISO 6432 standard – “U” series and “P” series Ø8 ÷ 63: ideal for lighter uses and in applications with less force.
Compact cylinders to ISO 21287 and AFNOR standards – “BX” series and “BU” series Ø25 ÷ 100: suitable for machines where space is a determining factor.
Rotary actuators “WR” and “RX” series – Ø32: 125: rotary actuator provides angular or rotary movement and it is available in rack rotary version.
Rodless cylinders – “Z “series Ø18 ÷ 63: this double acting linear cylinder is light and resistant.
Linear actuators in stainless steel: for use in highly corrosive environments, such as food or pharmaceutical industry environments, ISO linear actuators in stainless steel comply with ISO 6432, ISO 15552 & ISO 21287 standards.
Screwed round cylinders with integrated accessories – “HB” Series Ø20 ÷ 100. These cylinders differ from the others in coming with the accessories integrated in the end-caps and they are consequently cheaper.
Typical applications of pneumatic cylinders or pneumatic actuators
Pneumatic actuators and pneumatic cylinders can be used in a wide range of applications and they are particularly common in factory automation systems. This includes production, handling and packaging of the materials in which they are used to position or to move parts or tools and to carry out “pick and place” activities. Other operations include clamping, in which a work piece is held in position by jaws operated by the cylinder and punching, where the thrust of single acting pneumatic cylinder can be used to mark an object.
Manually operated spool valves for hook-loaders. “EK” series valves have been designed and developed to be mounted on industrial vehicles, such as hook-loaders and to guarantee excellent performance despite the compact size. The configurations for hook-loaders vary from 3 to 6 positions.