Pneumatic Cylinders Made Simple

Pneumatic cylinder calculations can be done in a matter of minutes, if not seconds, with DZynSource. From the main screen choose the "Fluids" command button.   The Fluids sub-menu appears, and you'll want to select the "Pneumatic Cylinder Calculations" command.

The blank pneumatic cylinder form appears. As with almost all of the calculations within DZynSource, you must choose metric or imperial units to work with as your first step.

You are now offered the option of calculating what size pneumatic cylinder you need to accomplish your task. If you know the force that must be generated, you enter that into the text box provided next to the "Enter the force that the cylinder must generate" text. You are also asked enter the air pressure that will be provided to the cylinder. The sizing of the piston is based on this premise: you want to deliver a force that is double the minimum force required. A smaller cylinder will move slower, due to being under-powered. a larger cylinder will usually move slower too, due to the increased volume of air required.

The calculation provides a size, and you would choose the next larger size of standard cylinder. For example, if you needed to push with a force of 450 pounds, and you have a line pressure of 80 p.s.i., you would need a 3.758 inch diameter piston. You would choose the next larger standard size, or 4 inch diameter piston. See the picture below.

In this case we have calculated an appropriate piston size, which is 4.000 diameter. I next entered all of my know data for the project that I'm working on. The piston I chose has a 1.000 diameter rod, a 12 inch stroke, a compressed air supply at 80 pounds per square inch, and we need to cycle the cylinder 10 times per minute, or every 6 seconds. Press calculate and we see that the forward force will be just over 1000 pounds. The return force is always less that the forward force because we have to subtract the piston diameter from the piston diameter. The air cannot act on the area of the piston rod. We are also given the standard cubic feet per minute of air that will be required to run this cylinder at this cycle. This information is used to determine the extra compressor load, and to size the valves that will control the air flow. That's all there is to it.