Non-Repairable-air-cylinders

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Non-repairable-air-cylinders: What do you need to know?

Non-repairable-Air-Cylinders also commonly known as "throw aways", are a family of lower cost air cylinders that are usually manufactured with aluminum end caps and with a stainless steel tube for a cylinder barrel.

The end caps are often cast with minimal machining involved to help keep the manufacturing cost low. Some non-repairable-air-cylinders have machined plastic end caps.

Each end cap has a groove cut around the circumference. After insertion of the piston and rod assembly into the cylinder barrel, the end caps are inserted into the stainless steel tube barrel material so that the grooves in the end caps are inside the circumference of the barrel.

The stainless barrel material is then roll-formed into the groove in the end caps to finish the cylinder assembly.

This is a faster and lower cost cylinder manufacturing process than is assembling the end caps to the cylinder with rods and bolts like the "repairable" family of air cylinders.

As a result, non-repairable types of air cylinders are lower cost than a repairable cylinder of the same bore and stroke.

It also means that this type of air cylinder cannot be disassembled for repair.

The non-repairable-air-cylinders are also known as "throw-aways", as that's what happens when they've reached the end of their useful life.

Perhaps the piston seals have worn so badly that the cylinder can't generate any force, or the cushion seals are gone, or the impact of the piston on the end caps ultimately causes a component fracture. It could be that the relatively small diameter rods have experienced sideloading , which damages the cylinder beyond repair.

Regardless, once they don’t work properly, the appropriate destination is the metal recycling bin.

Non-repairable-air-cylinders offer a number of options that allow selection of the appropriate cylinder combination for the application.

These options include a variety of mounting styles.

Note that unless the cylinder and the mounts are built to a standard such as ISO 6432 , each manufacturer's cylinder and mounts may have different dimensions. This could cause replacement-cylinder availability problems.

It's usually a good idea when purchasing a non-repairable cylinder (or any actuator for that matter) to select one that has been built to an industry standard so that, in the event your present brand of cylinder is not available in the future, you can substitute a cylinder with the same exact dimensions from another vendor.

Some additional options for non-returnable type air cylinders are:

Alignment couplers

Block style mounts (either rod or back end cap is square with through holes for mounting)

Clevis mounts

Cushions

Double End rod (the rod protrudes from both ends of the cylinder

Foot Mounts

Non-rotating rod (perhaps hexagonal, or dual rod)

Nose mount (usually standard)

Proximity Switches

Rear thread mount (often standard)

Trunnion Style Mounts (trunnions can be rod end, rear cap or centrally mounted to allow the cylinder to pivot)

As a norm, non-repairable type air cylinders are available in bore diameters from under 1/2" to over 2 1/2".

What do you need to know to select the appropriate non-repairable air cylinder for your application? Here are some tips:

What bore size? (How much force needed including allowance for friction inside the cylinder and a safety margin)

What stroke? (What is the distance you want whatever’s attached to the rod move? For longest cylinder life, the cylinder piston should never “bottom” at the rod or back end cap)

Is the cylinder to be cushioned at one or both ends?

Does the cylinder need a magnet on the piston for position sensing?

How will the cylinder be mounted, and what are the dimensions of those mounts?

How will the cylinder rod(s) be attached to the item you are moving?

What are the port sizes, so you can be sure you have the correct air line fittings?

Will flow controls be necessary for your application?

Will the application require a lubricator, or will the factory lubrication suffice? High-speed cycle rates may require additional lubrication. Check with the cylinder vendor.

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