Double Acting Air Impact Timer

Q: We are currently using your Double actioning 8 Ton stamper, to stamp stainless steel fittings. When using the stamper (in a automated process), we are experiencing “Double Stamping” which is making the impression hard to read. We are wondering how we can prevent this.

A: Thanks for contacting our on-line help with your marking question.

First I noticed you said it is in a automated application, which is great info and helps me to better reply with suggestions for you to check on.

To the point I will give you some bullet points to check first.

1. The part needs to be held so it cannot bounce back into the stamps as the marker begins to retract.
2. (note you cannot see this with the naked eye as it happens when the stamps are just coming off the part and might only be .005” away).
3. The part needs to have a solid strong back up with the parts against it when the marker is advanced.
4. Make sure there are no speed/ flow controls installed on the marker, it has a fixed internal speed control – This would be for a Slide-A-Mark
5. The time for the advance air from the valve needs to be at a minimum, often we tell people to adjust the dwell timer to zero. This is very important as the Slide A Mark is very fast and when the air in the front exhausts out the vents the hammer then fires. If the air is still filling in the chamber when the hammer strikes the rod (producing the needed marking force) it will bounce back and the return air should keep it going back and held against its return position until it is fired again. If the air is still filling when it bounces back from striking then the air will propel the hammer back down and you will get a ghost second impression.
6. If you have a single solenoid CMT Retro Fit valve pack this is very easy to adjust with the air dwell timer on the valve. If you do not then I would assume you have a PLC firing a solenoid operated valve. You need as short as possible on time on the advance and return it as quickly as possible. Sometimes the “Scan time” alone in a PLC is actually longer than is needed.
7. Check the air line length from the valve to the marker it should not be more than 3’ if possible otherwise the valve shifts and the air doesn’t have enough time to fully exhaust or fill the marker as needed.
8. Also check the air pressure regulator, Set it to get a good depth mark and watch it when the marker is operating. If it drops (varies) more than 5 to 7psi then you are starving it and need a bigger air supply. This is a good rule of thumb for anything that operates on air

I am thinking Item 5 & 6 are the most common causes of dbl marking and you might want to focus on this point first.

Here is a link to our std. valve pack with the air timer, we also use this whenever we do a turnkey installation.

http://columbiamt.com/CMT-Impact-Marking/Valve-Packs.html