advantages of using nitrogen?

[anthony]

noticed some folks are using nitrogen instead of air for CNC plasma cutting.
in fact i'm seeing a host of gases including argon and argon/helium mixes.

anyone know why? significant advantages?

-anthony

[Halfnutz]

Cleaner cuts. Depending on the metal your using. Most originally came out using CO2, then some low end vendors started selling the compressed air machines, now they are popular. I dont know a whole lot about it, but it ( an inert gas) basically acts as an oxidizing shield as well as the propellant for cleaner cuts in certain metals. Maybe someone else would comment on the types of metals its used for. (This is just a geusse, correct me if I'm wrong)

[murphy625]

Moisture content..

Plasma cuts best when using dry air.. Any moisture will also wear out the tip..

They arent just using nitrogen, I think the technical term is "dry nitrogen".. (I use it to remove oxygen from containers of polyurethane because oxygen reacts with the urethane and the nitrogen extends the storage shelf life)

I have also used it with my plasma cutter.. I have good dry air so I didnt notice much difference to speak of.

Its just a moisture thing as far as I know becuase most compressors will have moisture in the storage tanks.

Murphy

[Halfnutz]

Dont they still use CO2? I thought that CO2 was better than plain air? I also thought that there were other gasses used as well. I dont know for sure, correct me if I'm wrong.

[murphy625]

Im no expert either.. But I own a Hypertherm PowerMax 1000 and have used various others as well over the past 15 years.

I mostly cut carbon steel plate, stainless, and aluminium by hand held cutting.. (I can make one mighty fine cut +/- 1/32" on a good day, but am still no match for a machine)..

Like I said, I have used compressed nitrogen when we didnt have good dry air available.. Not much difference but there is a big difference when there is moisture in the supply.. (major no no)

I know some of these CNC cutters are high speed, and make some pretty crazy intricate cuts.. Im not sure how the gas supply stream would affect cuts that fine.. Somehow, I dont think it would make a knock-you-out difference. (but my lack of experience could prove me wrong)

Murphy

[umbriel971]

Different gasses will have different effects on the materials that you cut. Nitrogen is usually used as a stabilizer with argon to add a wetting action to a weldment and to keep the cost down. Same with C02. Nitrogen and C02 are reactive gases, helium and argon are inert but expensive. Helium will result in a "hotter" cut and may be more useful in thicker materials, couple it with a mixture of argon and C02 to reduce costs.
If you are after a minimal HAZ with the cleanest cut, I wouldnt use a pure C02 or Nitrogen, both could cause some oxidization of the material or a martensitic layer in the HAZ in ferritic materials. You might try putting an air dryer on your compressor to keep moisture out. In the long run it will be more cost effective that running with a compressed gas.

Hope this helps

[DCparts]

Different gasses for different materials and thicknesses. Not only does it effect the cut quality, but the speed, and the kerf width. I use: (the first is the plasma gas, the second is the shield gas)

O2/Compressed Air for Mild steel .135 and above

O2/O2 for Mild steel below .135

H35 (35% hydrogen 65% Argon)\Nitrogen for stainless steel over .375"

F5 (5% hydrogen 95% Nitrogen)\Nitrogen for stainless .375 and under

H35\Nitrogen for .375" and above for aluminum

Compressed air\Compressed air for aluminum less than .375"


I have to highly recommend the F5 gas for stainless steel, it gives you a beautiful bright cut. It is a relatively new mixture so not many supply companies have heard of it, but it is great.

[cut more]

If you use different gasses in the plasma cutter, do you need to do anything to run them through the plasma cutter? i.e. oil in an oxygen regulator is Bad. I have a Hypertherm 1000, I have cut stainless (22 gauge) and the edges were ok but the Dross had to be ground off. Would a different gas help?

DC Parts,
Shield gas, Plasma gas? My HT only runs 1 gas, What are you running for a Machine?

[DCparts]

It is a Hypertherm HPR130 http://www.hypertherm.com/mech_systems/hpr130.htm

I have not cut 22 GA with our new system, but on 16 GA 304 SS there is no clean up required.