There is a lot to be said about pneumatic actuators in general, but this article will concentrate solely on pneumatic cylinders. And since you are reading this I’ll assume that you have a general idea about pneumatics, and do know what is pneumatic cylinder and how does it work.
Pneumatic market constantly evolves offering different kind of pneumatic cylinders, which at the moment are fairly significant group of pneumatic actuators used in various industries. There are many different types of them, and they can be distinguished by various criteria.
Lets start from piston rod. Usually when thinking about pneumatic cylinders you imagine cylinder with rod on one side, but there are also other types. There are cylinders with double sided rod, which work basically very similar to traditional cylinders. Take a look at this shop, they have wide range of pneumatic products.
Of course rod movement is bilateral, when it hides on one sides it extends on the other. Most least known group of pneumatic cylinders are rodless cylinders. In those cylinders piston is connected to external carriage and no piston rod extends outside it.
Rodless cylinders is ideal solution when there is a need for really long stroke, they can have strokes up to 8000 mm which is unlivable in any traditional cylinder because of rod overhang and bending. Interesting choice especially in narrow spaces.
Other way to group cylinders is their ISO standard. From that point of view we can differentiate few types. First of all there is ISO 15552, which is round or flat (square shaped) cylinder, probably most common cylinder type around the world, there is also or ISO 21287 known as compact cylinder, and there are also mini cylinders.
Mini cylinders (standard ISO 6432) are most interesting since there are extremely effective in various high-end applications like advanced machinery or robotics. Compact cylinders are common whenever space is requirements since they are slightly smaller then ISO 15552 alternatives.
Most popular are round and flat cylinders. In round cylinders tie rods are visible on the outside, and in square (or flat) cylinders everything is contained inside special housing. Square cylinders seems more robust and solid choice, and additionally you can easily mount piston position sensor on it.
Since I mentioned mini cylinders I have to mention so called cartridge cylinders which are tiny cylinders with bore size and stroke even below 10 mm (up to 16), those cylinders are specifically designed for very sophisticated applications.
There are various special variants available for pneumatic cylinders, sometimes available as standard, but most likely optional. Those functions are usually needed for special applications.
Extended piston rod is relatively popular one. In this case cylinder stroke stays the same, but piston rod extends more on the outside compared to default norms described by ISO standard.
Other popular choice is so called amortization which can be mechanical or pneumatic. Amortization provides smooth contact of the piston at the end cylinder position – there is no collision. In some types of actuators amortization can be regulated.
Piston rod can rotate around its own axis during move, this is normal thing, and it usually doesn’t cause any problems in most applications. But it is possible to order cylinder with so called anti-rotation feature.
Very popular variant is so called tandem. Its solution which uses two cylinders connected in series which share same piston rod and have two pistons. When compressed air simultaneously enters to cylinders the force of both cylinders is added together, so that the final strength of the front piston rod is almost twice as high.
Pneumatic cylinder types, and variants mentioned above are only most popular ones, there is more to be said about them and other types. There are for example UNITOP cylinders, ISO 5211 rotary cylinders and much more. I am aware that not exhausted the subject, but at least something left for later. This introduction should give you general idea about cylinders, and I hope it did. If you have any questions feel free to ask them in the comment section.