Electromagnetic valves on CD102

[witer30]

Hello,
Can you advice how to dismantled an electromagnetic valves used on CD102. I mean M2.184.111, it is festo mebh-4/2-qs-6-sa. I was not able to remove a main piston... Can someone advise please...

 

[Kylin machinery]

This type of Festo solenoid valve uses a piston slide (spool) mechanism. When the main piston gets stuck, it is usually because the internal pneumatic grease has dried up and hardened over time, or the rubber O-rings have aged and swelled, firmly wedging the piston inside the valve body bore.

Steps and Tips for Removing a Stuck Piston:

1. Initial Disassembly: Ensure the valve is completely disconnected from the air supply and power, and removed from the press. First, remove the solenoid coil and the pilot valve section on top, then take off the end caps at both ends of the main valve body.
2. Do Not Use Hard Metal Tools: The internal bore of the valve is made of precision-machined aluminum. Never use a flathead screwdriver or any hard metal tools to forcefully pry or strike the piston. If the inner aluminum wall gets scratched, the valve will permanently leak air and be completely ruined.
3. Soak and Penetrate (The Crucial Step): Spray a generous amount of pneumatic penetrating oil or a rust penetrant like WD-40 into the air ports and both open ends of the valve body. Let it sit and soak for anywhere from 15 minutes to a few hours. This allows the solvent to break down the dried grease and lubricate the seized O-rings.
4. Safely Extract the Piston:
   
   • The Soft Rod Method: Find a wooden dowel, plastic rod, or nylon rod with a diameter slightly smaller than the valve bore. Insert it into one end so it rests against the piston, and use a rubber mallet to gently and evenly tap the rod, pushing the piston out the other side.
   • The Low-Pressure Air Method: If you have an air blow gun, you can introduce low-pressure compressed air from one side to "blow" the piston out. Caution: You must securely cover the exit end with a thick towel or several layers of soft rag to catch the piston. Otherwise, it will shoot out like a bullet and become damaged upon impact.
5. Clean and Rebuild: Once the piston is out, use a lint-free cloth to thoroughly clean both the piston and the internal walls of the valve body. Replace all the aging O-rings (seal repair kits for the M2.184.111 are available on the market). Before reassembly, you must apply a proper pneumatic grease (like Festo's recommended lithium-based grease) to the seals and bore.

If the piston absolutely will not budge after soaking and tapping, or if you find the internal bore is severely scored once it's out, the best course of action is to purchase a brand-new replacement valve to ensure the press runs smoothly.

 

[witer30]

Thank you very much...

 

[Joe Burger]

This type of Festo solenoid valve uses a piston slide (spool) mechanism. When the main piston gets stuck, it is usually because the internal pneumatic grease has dried up and hardened over time, or the rubber O-rings have aged and swelled, firmly wedging the piston inside the valve body bore.

Steps and Tips for Removing a Stuck Piston:

1. Initial Disassembly: Ensure the valve is completely disconnected from the air supply and power, and removed from the press. First, remove the solenoid coil and the pilot valve section on top, then take off the end caps at both ends of the main valve body.
2. Do Not Use Hard Metal Tools: The internal bore of the valve is made of precision-machined aluminum. Never use a flathead screwdriver or any hard metal tools to forcefully pry or strike the piston. If the inner aluminum wall gets scratched, the valve will permanently leak air and be completely ruined.
3. Soak and Penetrate (The Crucial Step): Spray a generous amount of pneumatic penetrating oil or a rust penetrant like WD-40 into the air ports and both open ends of the valve body. Let it sit and soak for anywhere from 15 minutes to a few hours. This allows the solvent to break down the dried grease and lubricate the seized O-rings.
4. Safely Extract the Piston:
   • The Soft Rod Method: Find a wooden dowel, plastic rod, or nylon rod with a diameter slightly smaller than the valve bore. Insert it into one end so it rests against the piston, and use a rubber mallet to gently and evenly tap the rod, pushing the piston out the other side.
   • The Low-Pressure Air Method: If you have an air blow gun, you can introduce low-pressure compressed air from one side to "blow" the piston out. Caution: You must securely cover the exit end with a thick towel or several layers of soft rag to catch the piston. Otherwise, it will shoot out like a bullet and become damaged upon impact.
5. Clean and Rebuild: Once the piston is out, use a lint-free cloth to thoroughly clean both the piston and the internal walls of the valve body. Replace all the aging O-rings (seal repair kits for the M2.184.111 are available on the market). Before reassembly, you must apply a proper pneumatic grease (like Festo's recommended lithium-based grease) to the seals and bore.

If the piston absolutely will not budge after soaking and tapping, or if you find the internal bore is severely scored once it's out, the best course of action is to purchase a brand-new replacement valve to ensure the press runs smoothly.

Hello, I have a question about this cover of SM52 year 2004: There are three solenoid valves behind it, and I need to replace one of them. This is always a bit tricky. How easy or difficult is it to remove this cover without having to open the spring-loaded latch? I would appreciate a reply.

 

[Kylin machinery]

It is generally not recommended to try and pry or force that cover off without disengaging the spring-loaded latch. The latch is there specifically to secure the cover tightly against the vibration of the press and to protect the pneumatic block behind it.

If you try to bypass or muscle past the latch, you run a high risk of either snapping the plastic/metal mounting tabs on the cover itself or bending the internal bracket that holds the solenoids.

The best approach:It might seem a bit tricky or tight to get to, but taking the extra minute to properly release the spring-loaded latch using a small flathead screwdriver or a pick tool will save you from breaking the cover. Once the latch is depressed/released, the cover should pop off quite easily, giving you clear access to swap out that solenoid valve.

Make sure to mark your pneumatic lines before pulling the valve!

 

[Joe Burger]

Thank you so much for this information. As I can see in the spare parts drawing, the spring block is mounted on the side panel of the machine. The cover could therefore be removed relatively easily once the latch is opened, the two screws are loosened, and the knob is removed.
I don't want to open the spring block. As I can see, HEIDELBERG made a design change on machines manufactured in 2004.
It seam to me that it is not that difficult as it was at machine year 1996 to 2002.
I'll try that out on a machine on Thursday.

 

[Joe Burger]