Are you ever stumped by the measurements written out on diagrams that spell out how different pneumatic installations are supposed to be connected? Don’t feel embarrassed if that’s the case. It happens to the best of us.
Over the years, different manufacturers have decided on a number of various standards and methods of doing things. That’s led to some confusion that’s, fortunately, starting to vanish because modern components are all measured using a standardized system.
Due to the fact that they’re three-dimensional objects, pneumatic cylinders can be measured in several different ways. That makes it a challenge to figure out exactly the specific part that you need, but it’s not nearly as much of a challenge as you might think once you know a few tricks of the trade.
At SMC Pneumatics, we’ve been able to offer a convenient cylinder bore sizing calculator that should help you to find the exact part size you need. In fact, you can use it without any information about the background of how these calculations are performed. That being said, it may help to run over the basic algebra that’s done by the system so you have a good idea of what’s going on.
Figuring Out The Bore Size Of A Pneumatic Cylinder
You can determine the area inside of a pneumatic piston simply by using the formula F=PA, where P is pressure and A is area. Product F is equal to the total force. Therefore you could solve for the area by using A=F/P and plugging in the two figures you already have. Since you know how much force will be needed to do the kind of work you’re interested in, you can multiply this by the amount of pressure you plan on working within your compressed air-driven circuit to give you the total amount of area you’ll need in a cylinder.
From the area required, you’re able to calculate the diameter of the cylinder. In most cases, you’ll hear engineers refer to the area of a pneumatic cylinder as the bore of the cylinder. This is in reference to the fact that the cylinder itself has to be bored out in order to make this space.
In order to find the bore, take the square root of the area and multiply it by 1.1284 to find a diameter. While this might sound complicated, it literally takes just a few seconds even with a traditional five function digital calculator. You could probably do it with the built-in app that comes with many smartphones and tablets. Of course, you could also use our air valve sizing calculator, which would factor in the available air pressure, cylinder bore, stroke length, and the time each stroke takes.
In many cases, you might not even need to get this specific though it does help. Cylinders are generally available at only specific bore diameters. Consider the NCQ2, which is available in bore sizes from 12mm to 100mm in the following delineations:
- 12mm
- 16mm
- 20mm
- 25mm
- 32mm
- 40mm
- 50mm
- 63mm
- 80mm
- 100mm
If you found that you needed a cylinder that measured 62.878mm exactly, then a 63mm bore size would probably work just as well. In most situations, this small deviation wouldn’t even be measurable. Considering slight fluctuations in airflow and humidity, the actual exact size measured at any given moment would possibly change ever so slightly anyway. These figures aren’t normally significant because pneumatic parts have evolved to the point where they’re extremely reliable and not subject to such slight variations.
Regardless of the bore size, you’re going to be looking at, the next thing that you need to consider is the stroke of the piston.
Measuring Pneumatic Cylinder Stroke
Stroke refers to the length of the area in which the piston moves back and forth. Those who are used to working with automotive components are more than likely quite familiar with this concept, and it also has analogs in almost every other facet of mechanical engineering.
Think about the NCQ2 part we were discussing before. It comes in a variety of different sizes, offering uses a stroke range that measures between 5-100mm so they can enjoy the same level of flexibility they would get when trying to select a specific bore size.
Once you’ve decided on the stroke length, you’ll want to give some thought to the different types of mountings available within that particular size. NCQ2 modules offer through-hole mountings, which are sometimes considered a standard that’s hard to beat. At the same time, you could also find competing technologies like threaded mountings as well as a clevis, foot, head, flange, and rod flange mount points.
These come in standard sizes, so you won’t have to worry nearly as much about sizing them properly as you would with the bore and stroke parts. All you really need to do is figure out how much header space you need to install a particular piece of equipment and you’ll be able to work with it as soon as you have it positioned in place.
Another factor you may want to consider, at least if you’re working with any significant number of valves, is the volume of air required by the circuit in question. This is measured in cubic inches. You’ll also see cubic feet per minute as a metric along with the coefficient of flow. That’s normally measured against a 2, 5, or 10 PSI pressure drop.
Nevertheless, these figures are normally based on more on-air valves. To recap for pneumatic cylinders, the four variables you’ll be working with are:
- Required Force
- Available Pressure
- Required Area
- Cylinder Bore Size
Achieve Your Desired Force With SMC Pneumatics
SMC Pneumatics is ready to help you find the right pneumatic cylinder for your setup. Our representatives can answer all your questions about model sizes and the force required to power them.
Once you’ve figured out what size of the part you need, make sure to contact us online and let us know if there’s anything more we can do. We always make sure to keep countless sizes in stock to help people regardless of what specific type of equipment they’re working with.