You’ve heard about MIG welding and you’ve been told it needs gas.
And now you want to check if it’s true.
Does MIG Welding Require Gas?
Gas is used to create a tight, protected space around the molten hot metals in your weld puddle.
Gas is required because there are parts of the air you breathe that affect hot metals. The normal air mixture causes your weld to be weak and fail over time. And so a defensive atmosphere is required.
MIG Welding And Gas Need
If you look up MIG, the letters mean Metal Inert Gas.
This welding process literally has gas in its name.
MIG welding developments over time has meant that today the gas used to cover. And protect your weld from the air doesn’t now need to be inert gas.
The gas used just needs to be effective in protecting your weld puddle till your metal cools enough. So that the air around your weld has no bad effect.
And now there are a few ways to protect your weld from the air as it forms.
Traditional MIG Welding Needs Gas
True MIG welding uses a MIG welder. A MIG welder feeds in and uses gas from a high pressure cylinder or gas tank. This gas is known as your shielding gas.
The gas is fed through your MIG welder up to the point of your MIG gun. And as your MIG welding wire feeds, your gas feeds at the same time.
You set the speed you want your gas to feed out to your MIG gun. You do that using your gas regulator attached to your gas cylinder.
And as you weld the shielding gas protects your weld from the air.
This way of welding is what’s historically called MIG welding.
What Type Of Gas Does MIG Welding Require?
The needed gases depend on what metal you’re welding. How sensitive you are to cost, as well as the visual results you want.
- You use 100% Carbon Dioxide when you want to keep the cost of gas low. You want a good weld, but your MIG weld doesn’t have to look the prettiest.
Carbon Dioxide isn’t an inert gas but it can effectively shield the hot weld puddle. You can use Carbon Dioxide when MIG welding mild steel.
- 100% Argon gas is required when you want to MIG weld Aluminum. Aluminum is already reactive with air. So an inert atmosphere is needed. Argon is an inert gas.
When you MIG weld Argon protects the hot Aluminum from the air well. But 100% Argon gas is more expensive.
- In the middle of these two extremes you have C25. C25 is 75% Argon 25% Carbon Dioxide. And this gas is most often used when MIG welding mild steel.
There are different Argon Carbon Dioxide mixes used in MIG welding mild steel.
- 80% Argon, 20% Carbon Dioxide is known as 80/20. Or 90% Argon, 10% Carbon Dioxide for mild steel. These gas mixes are for when you’re looking for high quality results. And so you’re prepared to pay more for a higher Argon gas mix.
- There is also Tri-Mix gas needed for MIG welding stainless steel. Tri-Mix gas is made up of 90% Helium, 7.5% Argon and 2.5% Carbon Dioxide.
MIG Welding That Requires Gas In The Welding Wire
Another type of welding that is often called MIG welding. Is in fact really Flux Core welding.
This type of welding uses special welding wire. You use this wire either in your MIG welder. Or in your Flux Core welder.
A flux core welder is a specific kind of welder. It cannot feed in shielding gas from a separate compressed gas tank. But it does use and feed gasless flux core welding wire.
Flux Core Welding Wire Is Different To MIG Welding Wire
Flux Core welding wire is formed like a long tube.
MIG wire is solid wire made of the same metal you’re MIG welding.
With Flux Core welding wire you’ve your filler metal around the outside of the tube. This filler metal is typically mild steel for welding mild steel. Or can be stainless steel for welding stainless steel.
And inside are chemical compounds called flux.
The flux is chemically made so that when the electrical arc melts your metal and your welding wire. A protective gas forms.
This gas protects and shields your weld puddle from the things in the air that would cause a poor weld. And make your weld porous (have holes in) and fail.
What If You MIG Weld Without Gas?
Say you wanted to MIG weld and not use flux core welding wire.
Or a separate tank of compressed shielding gas, with solid MIG wire.
Instead you just feed solid MIG wire through your MIG welder or Flux core welder and no gas.
What would happen?
All the things in the breathable air that have a bad effect on hot metal would get to your weld. There would be nothing to stop it. And the result would be a poor weak weld.
And for your question does MIG welding require gas? Now you’ve learnt that MIG welding does need gas. But that gas does not have to come from a separate compressed gas tank.
Gasless Flux Core welding wire in either a MIG welder or a Flux Core only Welder can provide the gas to shield your weld.
If you’re curious to know more about the subject, do take a look at the other related articles on the site.
About Bill Byers
I started welding at 27 and now have over 20 years on the job experience. I MIG, TIG and flux core weld. Even done a bit of Blacksmithing in my time.
I enjoy helping novice welders find their feet.
In my spare time you’ll find me enjoying a game of football.
And on the odd weekend paying a round of golf badly. Just duck when you see a golf club in my hand.