Several maintenance workers have been “pencil whipping” the preventative maintenance work orders for a machine with multiple pneumatic cylinders. The operator of the machine noted in his last downtime report that the cylinders are sticking and the machine is not working like it should. What might be some causes of the cylinders sticking and what actions should be taken to correct the problem?
The correct answer and explanation is:
Several causes could lead to pneumatic cylinders sticking, which could be due to a lack of proper maintenance or operational issues. Common causes include:
- Insufficient Lubrication: Pneumatic cylinders require lubrication to reduce friction between moving parts. If the lubrication is not adequate or not applied regularly, it can cause the internal components to seize, leading to sticking or erratic movement.
- Contaminated Air Supply: If the compressed air feeding the cylinders is contaminated with dirt, moisture, or oil, it can cause wear and build-up inside the cylinder, leading to sticking. Moisture can also cause corrosion, further contributing to the problem.
- Incorrect Pressure or Flow Rate: Pneumatic cylinders are sensitive to the pressure and flow rate of the air. If these parameters are not set correctly or fluctuate, the cylinders may fail to operate smoothly. Over-pressurization can cause seals to deform, and low pressure can result in insufficient force to operate the cylinder properly.
- Faulty Seals: Over time, the seals inside the cylinder can wear out or become damaged. This can lead to air leaks or improper movement of the piston, which may cause the cylinder to stick or fail to operate as intended.
- Improper Cylinder Sizing: If the cylinder is improperly sized for the application, it can lead to excessive stress on the internal components. This can result in sticking, as the cylinder may not be able to handle the load or force it is subjected to.
Corrective Actions:
- Lubrication: Ensure that the cylinders are regularly lubricated as part of the preventative maintenance schedule. Use the correct lubricant for the type of cylinder and ensure it is applied at the right intervals.
- Air Quality Check: Inspect the air supply system to ensure the air is clean and dry. Install filters and moisture separators if necessary.
- Check Pressure and Flow Settings: Verify that the pneumatic system’s pressure and flow rate are set to the manufacturer’s specifications and adjust as needed.
- Replace Faulty Seals: Inspect the cylinder seals and replace them if they are damaged or worn out.
- Review Cylinder Sizing: Ensure the cylinder is correctly sized for the application and load requirements.
By addressing these areas, the performance of the cylinders can be restored, improving the overall operation of the machine.