MIG Welding FAQs

MIG Welding Different Materials

Can you weld aluminum with a MIG welder?

Yes, you can weld aluminum with a MIG welder. You need a MIG spool gun, aluminum wire, at least 150 amps of output (220V welder) and 100% argon shielding gas.

Can you MIG weld aluminum without using gas?

Generally speaking, no. Aluminum reacts with oxygen at the time of welding. The shielding gas from flux core wire usually isn’t sufficient to ensure a strong aluminum weld. You will need a steady flow of pure argon shielding gas to protect against oxidation of the aluminum as it bonds. The usual MIG mixed gas used for steel welding is not sufficient for MIG welding aluminum.

Can a MIG welder weld stainless steel?

Yes, you can weld 304 grade and 316-grade stainless steel with the MIG welder at 110V and 220V power. Before welding, you should clean the surface with a fiber cloth to remove traces of dirt, oxidation and wire brush bristle material.

Can you MIG weld cast iron?

Yes, you can MIG weld cast iron with the right technique. However, cast iron is brittle and porous by nature, has varying chemical mixtures, and fluctuating quality level. This doesn’t lend itself to strong welds.

If you MUST weld cast iron with a MIG welder, here are some basic tips:

1) Load your MIG with stainless steel wire

2) Change your gas to 80% argon/20% CO2 from the normal 70% CO2/30% argon

3) Bevel the edges of the pieces you intend to weld with an angle grinder

4) Slowly heat the cast iron up over the course of 5-10 minutes to about 300-500 C. You can do this with a blow torch or large propane torch. Or you could put the piece in an enclosed barbecue, sitting on an aluminum tray full of sand. Your kitchen oven is usually not hot enough for this step.

5) Once the cast iron piece is up to temperature, slowly stich weld the joint at low temperature and low wire speed. Weld in half-inch sections, move 2 inches, weld again, etc. Then go back and repeat until you have all the gaps filled in. Go slowly and reheat the piece regularly.

6) While you’re stitch welding you will need to keep the cast iron up to temperature. DO NOT LET IT COOL OR IT WILL CRACK.

7) After you’re done welding, slowly reheat it, turning the temperature of the torch or oven/barbecue down over the course of 20-30 minutes. This will let the piece cool slowly so the weld and cast iron shrink at the same rate.

8) When the piece has cooled down to room temperature, clean up the weld area with a wire brush and oil it to prevent rust forming.

Using a MIG Welder

Can you stick weld with a MIG welder?

Yes, but only if you have a mult-process welder with stick ARC welding process and electrode holder/stinger. You switch the function to “STICK”, change out your MIG gun to an arc welding electrode holder, insert the correct electrode for the material and thickness, set your voltage level and start stick welding. Most MIG and stick welders run on DC so you don’t need to change to AC.

Can a MIG welder be used as a plasma cutter?

No, a MIG welder cannot be used as a real plasma cutter. A plasma cutter super-heats a stream of gas and shoots it out of a torch tip at high pressure and velocity. A MIG welder is designed to flow cold gas at low velocity and volume to a highly controlled electrical arc at the end of the welding wire.

It is possible to use a MIG welder to cut through steel in a rough fashion. This is done by:

1) Turning the output amps way up
2) Turning the wire speed way up
3) Turning off the gas supply

What this effectively does is to create a fast-moving extremely hot wire tip with limited ability to fuse to the base metal. The high heat and speed of the wire melts and pushes the base material out of the way, leading to a gouge or cut.

This approach works for thin material up to 1/8 inch with a typical 220V / 200A welder turned up. However, the cuts are very rough and it wastes significant amounts of welding wire. You’re much better off using a real plasma cutter or a cutting wheel.

What Causes a MIG Welder to Pop?

There are nine potential reasons why a MIG welder is popping. To fix your MIG popping problem just work down this list, doing test welds on a scrap piece until you get a nice sizzle going.

1) Wire speed is too fast (not melting into the pool) or too slow (burning up away from the weld and losing the arc)

2) The metal is too thick for the speed you’re moving (you need to slow down)

3) Your wire diameter is wrong. If it is too small this will cause it to burn away from the weld pool. If it is too large, the wire can fail to melt, leaving unmelted wire in the weld.

4) Your heat setting is too low (“cold weld” where the wire doesn’t melt and breaks off) or too high (the wire can’t handle the heat and burns back from the weld, losing it’s arc until it touches down again)

5) You ran out of shielding gas

6) Your wire feeder is hanging up or mis-adjusted, causing the wire to come out in spurts

7) The wire is tangled at the feeder

8) You’re trying to weld with the wrong wire — e.g. you forgot to change to flux core wire after you took the gas tank off so you can weld outside

9) You’re not holding the gun the right distance from the weld. Too close and the wire will arc back into the gun tip or jam the wire into the weld before it can melt. Too far away and the wire can melt away from the weld pool, breaking the arc and wandering around.

Do you push or pull when MIG welding?

If you’re using flux-cored wire you generally want to pull the wire across the weld joint.

If you’re using shielding gas with solid metal wire you generally want to push the MIG gun as you weld.

Where Can I Find a MIG Welding Checklist?

MIG vs. Other Welding Methods

Which is Better? MIG or Stick Welding?

Both stick welders and MIG welders are popular. Let’s compare these two types of welders based on real-world factors. If you want a more complete analysis, check out our article that compares MIG and Stick Welding here.

Welding Speed
You need to use a consumable electrodes for stick welding. You need to change the electrode as it melts down. Changing electrodes slows down the welding process.

On the other hand, with a MIG welder the constant wire feed and gas flow allows you to weld continuously without replacing electrodes. Even a medium-sized gas tank and standard wire roll can be used for 3 or 4 days in a small manufacturing business.


Welding Skill
Welding with a stick welder is a complicated process and requires a higher level of skill and experience to weld. It’s challenging to produce clean, strong welds consistently with a stick welder due to the smoke, spatter and change in electrode length.

A beginning MIG welder with the right machine settings can start producing reasonably strong, clean welds within a few minutes. The skill curve to becoming an intermediate welder is flatter and smoother compared with stick welding.


Outdoor Use
You can use a stick welder in just about any outdoor environment. High winds, rain and ice pose little problem for a stick welder. This because the flux in the electrode creates a self-contained protective gas environment that expands outward from the weld.

With a MIG welder outside, a minor breeze can blow the shielding gas away, compromising the protection around the weld. This can lead to a certain level of weld porosity. Although you can use MIG welder in windy conditions using a special type of welder blanket or a welder’s tent, this complicates the work and may not be feasible.


MIG Shielding Gas

Does a MIG welder use gas?

Yes, MIG welders can use inert gas to shield the weld puddle. This is called Gas Metal Arc Welding (GMAW) and uses solid wire with C02 and Argon gas mix for steel. There is also “gasless” MIG or Flux-Cored Arc Welding (FCAW), which does not use gas. Instead it uses hollow wire with flux inside that vaporizes at the arc and expands into a shielding inert gas bubble.

Do gasless MIG welders work?

Yes, gasless MIG welders using flux-cored wire (FCAW) work very well, particularly on steel and iron. The expanding inert shielding gas “bubble” formed at the weld arc from vaporizing flux creates a highly effective shield against oxidation and other environmental contamination of the weld.

Because flux-cored gas expands outward from the arc, it is more stable and resistant to being blown away or diluted by wind or air currents. The vaporizing flux also carries impurities away from the weld pool, leading to stronger welds. In, addition, gasless MIG often penetrates deeper than gas MIG welds, since flux-cored wire burns hotter than solid steel wire and heats the weld area up more.

The downside to gasless MIG is the creation of “slag” on top of the weld that must be chipped away, and excess smoke and spatter which hinders visibility and requires additional grinding or sanding to remove, if the area needs to be smooth.

Generally, inert gas MIG and gasless MIG will produce equal strength welds when done properly.

Can you MIG weld with nitrogen?

Yes, you can MIG weld with nitrogen gas as part of the gas mixture. Nitrogen is semi-inert, similar to CO2 and can help with weld penetration.

However, there are downsides to MIG welding with nitrogen gas:

First, it can harm the weld quality if too much gas is used. Pure nitrogen will result in weak welds.

Second, it shouldn’t be used when MIG welding stainless steel as it reacts with the base metal.

Third, nitrogen gas is expensive and is therefore not cost-effective. In most cases, you’ll be better off using a CO2/argon mix in 70/30 proportion for MIG welding steel.

What gases are used in MIG welding?

The common types of shielding gas used with MIG welding are Argon (Ar), Carbon Dioxide (CO2) and Helium (He).

A standard gas mix for welding carbon steel or chromoly is 75% argon and 25% carbon dioxide.

100% Argon or a mixture of 90% argon and 10% helium is used for aluminum and aluminum alloys.

Setting Up a MIG Welder

What Amperage Outlet Is Required For a Welder?

For a 220V welder will need a 50 amp plug and a matching 50 amp 2- or 3-pole circuit breaker wired into your breaker box. You will also need a NEMA 6-50 or 10-50 plug and receptacle that can handle 50 amps of power safely.

For a 110V welder you can generally run it on a standard 110V wall outlet. You will need a 20-30 amp circuit breaker.

How much power does a MIG welder use?

The electrical power consumed by a MIG welding machine varies from welder to welder. A welder with 200 amps will generally consume around 4.6 watts.

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Nick Klamecki, Author
About Nick Klamecki, Author

Nick Klamecki is a certified Fire and Workplace Safety expert with 15 years experience in product research and testing. He has a degree from U.C. Davis, is an active outdoorsman and spent years ensuring the safety of special needs children. Nick researches and tests workplace, industrial and safety products and provides advice on their safe use. Learn more about Nick here or connect with him on LinkedIn | Medium