What Causes A Pneumatic Cylinder To Stick?

These might include not only unplanned downtime but also possible product defects and automation failures. 

All this should be avoidable with a regular programme of preventative maintenance. This will ensure that your equipment is free from contaminants, adequately lubricated and properly set up according to the original equipment manufacturer’s (OEM) specifications. 

Causes of Pneumatic Cylinder Sticking

When a pneumatic cylinder begins to stick, it might only be a subtle hesitation, which you might not even notice at first. If left too long, however, the situation can deteriorate rapidly and lead to serious difficulties. 

There are several things that might cause a pneumatic cylinder to stick; most of them are connected to dirt.

Contamination

To operate at maximum efficiency, a pneumatic cylinder must be kept scrupulously clean and free of contamination. This isn’t always easy in an industrial environment, where the machinery is often surrounded by dirt and debris, dust, rust and other particulates such as metal shavings. These contaminants can soon build up, clogging the works and either creating or exacerbating a mechanical problem. 

Contaminants can get into your cylinder at any time, whether during the installation process or in daily use if your air supply isn’t properly filtered. These contaminants can build up on the piston surface or inside the barrel, where they’ll create friction or abrasive wear on the components, which will gradually begin to restrict their free movement.

Inadequate Lubrication

Lubrication is an essential element of cylinder maintenance. While the compressed air supply will usually be cleaned, filtered and lubricated by an FRL unit, the cylinder seals are also critical. Adequate lubrication is necessary so that the seals don’t dry out and stick to the walls of the barrel instead of gliding smoothly along them. Make sure it’s the correct type of lubricant, too, as incompatible lube can also cause sticking problems. OEMs will usually specify the best type of pneumatic compatible lubricant to use.

Mechanical Misalignment

This is another common cause of a sticking pneumatic cylinder. You can introduce lateral forces into the cylinder’s motion if there’s even the slightest misalignment of the piston rod’s external load. These lateral forces will cause the piston to scrape along the cylinder wall, eventually causing the piston to drag or jam completely. Mechanical misalignment can be a much greater problem for cylinders operating under side loads, or those which have a longer stroke.

How to Resolve Problems with a Sticking Pneumatic Cylinder

The first step is to test the functioning of the cylinder, independent of its load. To do this, disconnect the cylinder from the load and see if it moves on its own without hindrance. If you find that the cylinder moves freely, then you’ll probably be looking at some external misalignment or connected components creating mechanical resistance.

If you find it’s the cylinder itself that’s sticking, disassemble it carefully and inspect it. Be on the lookout for debris and contaminants, excess moisture, corrosion or damaged seals. Go over all internal surfaces of the cylinder using approved pneumatic cleaning agents and lint-free cloths. All contact surfaces must be absolutely smooth and free of obstructions, especially on the piston, bore and rod guide.

When you’re sure the cylinder is completely clean, lubricate it thoroughly with a pneumatic-grade product. The lubricant must be compatible with both the cylinder materials and the environment in which it operates. Then reassemble the unit according to the manufacturer’s specifications, ensuring all the seals and spacers are precisely aligned. 

Using inline filters and air dryers will help prevent any contamination problem from recurring. To eliminate side loading, you must also mount any external loads using self-aligning couplers or special alignment tools.

What’s the Problem if your Cylinder Sticks?

If your cylinder jams or sticks, you’re going to be looking at a serious operational issue that might impact your entire production process. At the very least, you’ll be looking at a thorough cleaning and overhaul; at worst, you might have to replace the whole cylinder. 

By recognising the causes of pneumatic cylinder sticking, you can learn how to prevent them. With careful installation procedures and a regular maintenance programme, you can protect your cylinder from irreversible damage. This will reduce unplanned downtime and enhance the performance and accuracy of your pneumatic systems.