Can A Pneumatic Cylinder Be Repaired?

Post By: Holly Shaw On: 07-05-2024 Read Time: 5 minutes - Guides - Pneumatics

Faulty pneumatic cylinders can often be repaired – but preventative maintenance will keep repairs and replacement to a minimum. 

Like all industrial machines, pneumatic cylinders are prone to wear over time. System maintenance is needed to keep them in good working order to prolong the lifespan of equipment and prevent hazards. In this guide, we’ll discuss the signs of a faulty pneumatic cylinder, their causes, how to avoid them and when to repair them.

Pneumatic cylinders are used for various industrial applications because of their reliability and ease of control in repeat positioning. They’re used in automation for functions that require push/pull motions, lowering/lifting and clamping objects. They’re often used in packaging, assembly lines, sorting and other precision tasks. They’re also less expensive than electric actuators, making them an economical choice. 

Signs That A Pneumatic Cylinder Needs Maintenance 

Hissing Sound

A hissing noise from an air cylinder is an indication that there might be a leak in the unit. It can also signal a damaged rod seal or damaged piston. A worn-out rod in the system can cause a leak, which results in decreased pressure and output. 

Slow Actuation And Low Pressure

If the cylinder is working slowly or has stopped, it’s a clear sign that air pressure needs to be checked. Extremely high pressure is required to power actuators. If control lines are too small or there’s a problem with the metering choke valve, it can cause low pressure. Monitoring actuating pressure can help identify problems early on and prevent system shutdowns.

Intermittent Start-Up

Overloading a cylinder leads to excessive stress and friction to the sealing. It can also cause actuators to break apart, as the overloading pressure can bend or break rod ends. If the system uses speed-control mechanisms or energy absorption devices, they can influence pressure readings, causing them to spike.

Load Pulsing

Cylinders operating normally run silently with consistent pressure. Pressure fluctuations in the cylinder’s air supply lines could be related to the cylinder’s load. This is referred to as load pulsing. Pressure fluctuations reduce cycle times and accuracy, and lead to an overall increase in wear.

Corrosion In And Around The Cylinder

Rust or corrosion on the cylinder’s surface, end caps or piping often results from operating in environments with extreme temperatures, humidity or harsh chemicals. Severe temperatures and air conditions cause erosion and pitting to the cylinder’s structure and can lead to failure if not addressed.

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Causes Of Pneumatic Systems Failures 

Contamination

Since pneumatic cylinders operate with compressed air, debris such as dust can get into the system leading to contamination. Oil and moisture in the air can also rust piping and the cylinder’s components, causing blockages. Debris can build up in the system over time causing it to be less effective or even to shut down.

Side Loading

If pressure is placed laterally on the cylinder’s axis, it can damage the piston rod, causing it to be uneven. It can also lead to seal failure, scoring in the cylinder’s tube and wear to other parts of the system. Side loading typically happens when the cylinder is not correctly installed. When sideloading occurs, it needs to be remedied quickly to reduce damage.

Overworking And Synchronisation Issues

Overworking a pneumatic cylinder causes excessive stress on internal components, which will usually fail. Also, if the cylinder is poorly connected to other components, it won’t operate as efficiently. It’s important to connect pneumatic cylinders carefully and ensure they are correctly synchronised. 

Low Lubrication Levels

Ensuring the cylinder has the required levels of lubrication to operate reduces wear on seals and fittings, ensuring they don’t dry out and wear with pressure.

How To Implement Preventative Maintenance 

Step 1- Switch Off The Cylinder

Before carrying out maintenance, switch off the power supply to the cylinder and release any remaining air in the tank. Ensuring the tank is free of pressurised air is critical in preventing accidents. 

Step 2 - Look For Rust And Damage To Components

Examine the cylinder’s tank, rod seals and tubing because they are the most susceptible to rust and damage. Carry out a thorough assessment of these parts to look for corrosion or cracks in seals and fittings. If the damage to these components is significant it's best to replace the cylinder.

Step 3 - Check Lubrication Levels

Check the manufacturer’s instructions for the cylinder to assess how frequently the system will need lubricant to be applied. Take environmental conditions into account when determining lubricant levels – for instance, exposure to high temperatures and chemicals. Apply a layer of lubricant to critical components such as rod seals, tube gaskets and the inner and outer areas of the piston rod and seal.

Step 4 - Replace Cracked And Broken Seals

To replace cracked seals, carefully remove the rod cover and take apart the cylinder. Be sure to remove all parts, wiping grease from their surfaces. Replace seals, taking care to install them securely, then reassemble the cylinder. Tighten the tube covering a little more when reassembling the cylinder.

Maintaining And Repairing Pneumatic Cylinders

Pneumatic cylinders experience wear and glitches over their lifespan. But there are steps operators can take to ensure that systems don’t shut down unexpectedly. This requires looking out for signs the cylinder needs maintenance, such as hissing sounds and accumulated rust around fittings. Operators should have a guide they can consult, which includes the cylinder’s make and ISO standard. This will help when repairing the system or deciding whether it should be replaced.

As part of the cylinder’s maintenance checklist, it’s important to ensure cylinders are correctly installed. Proper installation requires fasteners to be accurately torqued before installing tie rods. Changing filters regularly prevents contaminants from building up and damaging the cylinder. Maintenance should also check for wear around fittings as debris can get into the system from rust on fittings and pipes. These are just some preventative measures. To read more, see our guide on troubleshooting pneumatic systems.