Shielding gas for MIG

[OldracerJones]

Do you have to use shielding gas with MIG? I've got a small MIG and it says it doesn't need shielding gas but seems like I could get better quality welds if I used some.

 

[goodysgotacuda]

You do not need shielding gas if you use Flux-core wire.

If you use solid wire, you will need shielding gas to protect and clean the weld site. Argon/Co2 is the most common for a MIG.

Quality welds can be made with either wire, aesthetics will vary. Each have pros and cons, for garage use, it's tough to beat using gas. If you are outside welding a trailer, building a fence, etc where it's windy, you'll want flux-core.

 

[zkling]

Yes, MIG = Metal Inert Gas.
The process you want to run is called flux cored or self shielded. All mig machines will run the flux cored process.

 

[Rock knocker]

By definition, you must use a shielding gas with a MIG. MIG stands for Metal-Inert-Gas and is also know as GMAW (Gas Metal Arc Welding). Flux core wire welding (FCAW) uses the same machines with different rollers and tips and can be plain cored wire with no shielding gas (FCAW-S) or "dual shield" (FCAW-G) using a gas shielded flux core wire.

But again, gas is required for all MIG welding

 

[OldracerJones]

Thanks guys, that is what I needed.

 

[tractordude]

I run a 75% argon/25%CO2 mixed with hard wire, pretty common.

 

[Engine]

Do you have to use shielding gas with MIG? I've got a small MIG and it says it doesn't need shielding gas but seems like I could get better quality welds if I used some.

Using flux-cored wire, it's possible to produce excellent quality welds without using gas.

Some of the disadvantages of flux-cored over solid wire + shielding gas are;
1) More spatter,
2) Slag must be removed (if it is to be painted),
3) More smoke and fumes,
4) Wire is more expensive.

Some advantages are;
1) Can be used in windy conditions,
2) It is somewhat more tolerant of mill scale and rust,
3) Since the wire stickout length can be much more than in GMAW it allows welding in grooves and other areas where the gas nozzle in GMAW would get in the way,
4) Less initial investment in gas bottle, gas, flowmeter, and cart to haul it all around on,
5) No tank attached to the welder, thus it is more portable.

I'm sure there are other pros and cons to each method that I didn't mention.

Basically, it comes down to what the majority of your welding will be. If you have a shop where you do most of your work then you might lean more toward the gas shielded solid wire process. It can allow you to possibly produce a nicer looking weld with less cleanup. If you are only welding occasionally doing repairs on equipment outdoors, or are more concerned with sticking steel together and making it hold than you are in how good the weld beads look, then FCAW might be more practical.

On second thought, maybe it's better to get both.

 

[Leaky88]

Good discussion. I have a Lincoln Weld Pack that I never seem to find time to be more proficient at using. Leaky

 

[little d]

I haven't tried it yet but have read where you can use CO2 with fluxcore to cut down on splatter, has anyone ever done this and what was the results?

 

[Professur]

I use CO2 on solid wire. Never tried it on fluxcore.

 

[tractordude]

I haven't tried it yet but have read where you can use CO2 with fluxcore to cut down on splatter, has anyone ever done this and what was the results?

Flux core wire welding (FCAW) uses the same machines with different rollers and tips and can be plain cored wire with no shielding gas (FCAW-S) or "dual shield" (FCAW-G) using a gas shielded flux core wire.

Here is your answer little d, ^^^^^ A dual shield weld will produce a nice weld even for a novice welder. It is smokey, and will have welding slag, much like a 7018 stick weld. IIRC, you will use a 100% argon gas

 

[little d]

Thanks for the reply Tractor Dude. Like I said, I've never tried it but, will this summer (now that I know it is worth the investment).

 

[BigMike782]

Be aware that dual shield wires are generally for applications beyond small home shop machines.
If you have CO2 just use S6 wire with CO2 or 75/25 argon/CO2 mix.

 

[fnieto]

Using flux core wire on a mig machine also requires DC electrode negative (straight polarity). conversely, running solid core wire with gas requires electrode positive (reverse polarity).
I know many of you already know this but some following this thread might not. That said, a machine with a gas solenoid can be converted to flux core wire with the correct rollers and electrode swaped to negative (straight polarity). Some welding machines (smaller 110 units) do not have the said solenoid built in and are only set up for gassless flux core welding.

 

[erty67]

All mig machines will run the flux cored process.

however not all flux core machines can run gas

 

[laser3kw]

But again, gas is required for all MIG welding

a generalization but true.
Gas from an outside supply (shielding gas cylinder) via the gun tip or a "gas" atmosphere from burning an organic compound within the wire (flux core)