3MB Ar gas distribution ring damage

[Max K]

Hello,

Has anybody seen the same damage (images attached) on 3MB Ar distribution ring? If yes, what was the cause?

Thank you.

[Lemster68]

Did you by chance also melt the tip of the powder injector?

[Max K]

Did you by chance also melt the tip of the powder injector?

No, I didn't. Powder injector is fine.

[Lemster68]

OK. I asked because if you have that ring installed and light it with Nitrogen as a primary gas, you can get a pretty good meltdown.

[Max K]

OK.  I asked because if you have that ring installed and light it with Nitrogen as a primary gas, you can get a pretty good meltdown.

I am running argon as primary, hydrogen as secondary. Tried Nitrogen gas ring with Argon just as a test. Nozzle deteriorates pretty fast. I am using Tafa controller so I think maybe something wrong with starting parameters. Currently the gun arcs at 50 slpm Ar and ramps to 300A.

[J!m]

That appears to be too low a gas flow for the power level.

Metco does offer a multi-hole Argon gas ring (it's brown) that is much higher temperature tolerant than the white ones. If you are stuck with your parameters (gas flows and power level) then you may want to look into that or use the 9MB gun.

I would also check the ignition parameters of that console. It is possible the open circuit voltage is excessive for the 3MB gun, and reducing it will preserve the parts better.

[Max K]

That appears to be too low a gas flow for the power level.

Metco does offer a multi-hole Argon gas ring (it's brown) that is much higher temperature tolerant than the white ones. If you are stuck with your parameters (gas flows and power level) then you may want to look into that or use the 9MB gun.

I would also check the ignition parameters of that console. It is possible the open circuit voltage is excessive for the 3MB gun, and reducing it will preserve the parts better.

Jim,

Thank you for your input. I am still in developing mode, so I am not stuck with parameters. Do you by any chance know part number for multi hole Ar ring? At this moment I am working with N2 ring (brown). Distribution ring holds on pretty good. The starting voltage setup is 100V. I am not sure if it is too much.

[paikhuan]

Hello,

Has anybody seen the same damage (images attached) on 3MB Ar distribution ring? If yes, what was the cause?

Thank you.

Hi,

Definetly, this happens first time you started the gun. You can check it, it is not a problem from use, it is related with a bad purge of water when you installed / mounted the argon ring /3mb gun.

Manufacturer's manual says that you have to do an Ar purge for, at least, 30 seconds with 60-70 lpm. In our area, after suffering this problem, we actually purge with that 60 lpm for at least 1 min.

This way, we spend more argon, but we manage to remove all the water inside the electrode/nozzle assembly, which is the cause of the argon ring deterioration during the first spark.

Try and tell us!

[J!m]

You don't want to use the Nitrogen ring with Argon primary. You must use an Argon gas ring. All the Argon rings induce a gas swirl which increases arc length which increases voltage. You will run excessive secondary to obtain voltage and hardware life will be poor, and the plasma condition will not be the same, despite the same voltage (because of total gas flow change).

P/N 1000687 is the one-hole Argon gas ring. These do melt when things wander off the reservation...

P/N 1000743 (I think so) is the multi-hole Argon ring, and it is also brown, which is higher temperature material than the white single-hole ring.

It might help (A LOT) to publish your parameters, or at least what exactly you are trying to do and maybe I can help.

100 volt open circuit is fine. Spark gap should be 0.014" (off the top of my head). If it's excessively wide, ignition spark will be overly aggressive.