MIG Welding FAQs

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 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 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.

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 the 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 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.

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:

  • Turning the output amps way up
  • Turning the wire speed way up
  • Turning off the gas supply

What you’ve effectively done is 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.

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. However, if you MUST MIG weld cast iron, here are some basic tips:

  • Load your MIG with stainless steel wire
  • Change your gas to 80% argon/20% CO2 from the normal 70% CO2/30% argon
  • Bevel the edges of the pieces you intend to weld with an angle grinder
  • 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.
  • 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.
  • 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.
  • 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.
  • 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.
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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

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