More About Air Actuators

This page provides more information about air actuators.

if you wish to review the information provided from the beginning, page one about air actuators can be found here.

On this page we get more into the sizing of air cylinders and actuators.

Rotary actuators are a pretty neat devices, and we talk more about them too. The picture of an SMC rotary actuator follows.

rotary air cylinder

You might find the rotary actuator you are looking for here.

Actuator Sizing

hot tip graphic   When sizing the air actuator for your application, you will want to understand this concept:

Force = Pressure x Area

Cylinder piston size is important. You might want to have a look at this page for more information on cylinder size and to better understand how the formula F=PxA applies to air cylinders in general, and the surface area of the cylinder piston in particular.

Once you know the surface area of the cylinder or actuator piston, by knowing the air pressure that flows into the cylinder it is fairly easy to calculate the theoretical force to be generated by that cylinder.

That force is available in theory only, as you will likely lose about 10% or so of the force that is available from a specific bore size cylinder just to overcome the friction created by the piston and rod seals inside itself.

While it has some cost ramifications, you might consider over sizing the air cylinder you select by at least 25% this to account for force loss to friction and to allow sufficient force-safety-margin when the cylinder is working.

Standard Cylinder Components

Standard air cylinders / actuators have traits that are common, regardless of the manufacturer or the specifications to which the cylinder is built.

The following diagram shows the parts of a tie-rod type air cylinder. These components will be common to all of this type. The actual dimensions for a specific cylinder will vary depending on the manufacturer's design, or the standard to which that cylinder is built ie: NFPA cylinder or ISO cylinder.

Air Cylinder Components Sketch

Types of air cylinder / actuators

The following are a list of links to pages on this site, providing more information about various types of air actuators.

  • Air Muscle; what the heck is that? Not a lot of folks know about this technology, yet it's been around for years now, albeit an unusual type of air actuator - more...

  • Diaphragm or Rolling Lobe air cylinders; There are a variety of air actuators available that are designed and built for a more specific reason than just the application of force. One of these is the diaphragm or rolling lobe type air cylinder - more...

  • Double-acting air cylinders! These are the work horses of the compressed air circuit, so named, because compressed air is used to both extend and retract the rod - a double action. more...

  • Grippers Aptly named. At the end of a cylinder or rotary actuator, or any pick and place application. more...

  • Linear Slides

  • Non-repairable-air-cylinders: There is a family of lower cost air cylinders that is usually manufactured with aluminum end caps and with a stainless steel tube for a barrel. The end caps are most frequently manufactured by casting, with minimal machining involved, to help keep the cost low. Some non-repairable-air-cylinders have machined plastic or composite end caps more.....

  • Repairable Air Cylinders; these are appropriately named simply due to the fact that they can be repaired when a component has failed. The most common type of repairable air cylinders are known as more...

  • Rodless, cable, band, magnetically coupled air cylinders; These are selected where a footprint issue prevents the use of a traditional and lower cost rodded type air cylinder - more...

  • Rotary-actuators; in the context of this web site, though there are rotary actuators powered by other than compressed air, we are talking specifically about pneumatic variety. The purpose of all rotary actuators is to provide the user the ability to move the tooling in a rotary motion, instead of the linear motion provided by air cylinders. more...

  • Single Acting Air Cylinders; what are they and why do we need them? Contrary to what may have been believed for years, compressed air is really quite expensive. If you have an air cylinder that's cycling in one direction under no load, or under low load, you can reduce your compressed air consumption and money by using a single acting air cylinder more....

The following provides additional general information about air cylinders and their use along with air cylinder accessories.