What Is Metal Inert Gas (MIG) Welding? A Complete Overview

MIG Welding or Metal Inert Gas Welding is a common welding process in 2021. It is an arc welding process that uses two materials that are melted together join two points.

MIG welding includes a solid wire electrode that is heated and fed into the weld pool. The welding gun then joins the two metals together. Moreover, a shielding gas is used with the electrode to prevent any airborne containments on the welding surface.

MIG welding is a versatile welding process and can be used for a variety of metals of different materials and base thicknesses. The quality of welds and successful MIG operations depends on the proper selection of MIG welders and their components including:

  • Shielding gas
  • Electrode
  • Process variables i.e. voltage, current, wire-speed, etc.
  • Equipment i.e. power source, wire feeder, and welding gun/nozzle

History of MIG Welding

MIG welding process dates to 1949 in the USA when it was first used to weld aluminum. The weld pool and arc were created using a wire electrode and the shielding gas used was helium. It was easily available at that time.

MIG welding became quite popular in the USA and UK for welding aluminum by the end of 1952. UK welders used argon as the shielding gas. Moreover, they also used the argon-CO2 mixtures called Metal Actie Gas Processes (MAG).  

What Is MIG Welding Process – A Complete Breakdown

MIG welding is a popular welding process used to weld both thick and thin materials. The components included in MIG welding metal are as follows:

  • Gas nozzle
  • Contact tube
  • Arc
  • Consumable electrode
  • Shielding gas
  • Weld pool
  • Parent metal
  • Filler metal

Don’t worry as modern MIG welding machines do not require you to deal with each of the above-mentioned components. You can expect to buy the best MIG welder for your work, set up in 10 minutes, and start working.

However, for those who are curious about the whole MIG welding process characteristics, keep reading and we’ll get there soon.

How Does MIG Welding Works?

MIG Welding, Metal Insert Gas Welding, Gas Metal Arc Welding (GMAW), or Wire Welding, is a simple welding process.

In MIG welding, a thin wire is fed from a spool that is mounted inside the welding machine through a flexible tube. The thin wire comes out of the nozzle of the welding torch. When you pull the trigger on the welding gun, the wire is fed continuously to weld the metals together.

Welding Trigger MIG Welding Nozzle

The welding gun trigger also switches on the shielding gas and welding current. This generates an electric arc that heats both parent metal and filler metal above their melting point. These metals melt together and join two workpieces into a single piece. The metal on the welding surface is called base metal or parent metal. Similarly, the metal that comes from the melting wire electrode is called filler metal.

In MIG welding, the filler metal is added to the joint and it melts throughout the welding process. Therefore, MIG welding is also referred to as a consumable electrode process.

The MIG wire fed from the spool goes through a flexible tube that goes through a welding lead (which comes with the welder). The welding lead goes all the way to the torch gun or nozzle. The wire is connected to a contact tip on the nozzle. The nozzle forms an arc to heat and join the base and filler metals, together.

MIG Welding Gas Diffuser

The nozzle also features a gas diffuser to push the shielding gas on the welding surface. The shielding gas is used to protect the melting wire electrode from any containments like oxygen, water vapors, and other atmospheric things.

On the backend, the shielding is stored in a highly pressurized gas cylinder.

To control the welding process, most of the machine controls are available on the front of the MIG welder. The most common machine controls include:

  • Voltage
  • Wire-speed
  • Polarity
  • Voltage
  • On/off switch

To sum it up, MIG welding is an arc process that uses a consumable electrode, filler metal, and shielding gas to prevent filler metal from reacting with any containments.  

Note that most MIG welders use direct current. The wire is positively charged, and the metal is negatively charged. The process often starts when the wire is connected to a power source. One can select the wire diameter, wire-speed, voltage, and other control settings on your MIG welders (some MIG welders have more control settings than others).

Types of Shielding Gas Used

Besides protecting the electrode wire, arc, and weld pool, the shielding gas used for MIG welding have several other purposes. Some of them are:

  • Easy transfer of molten filler metal from the wire to the weld pool
  • To stabilize and soothe the arc roots on the surface metal
  • To produce the arc plasma

Shielding gas that is used for MIG welding has a great effect on the welding quality. It stabilizes the metal transfer from the electrode to the base metal. It also enhances the behavior of the weld pool – ensuring more smooth penetration.

Some common shielding gasses used today for MIG welding include a mixture of CO2, argon, oxygen, and a mixture of helium too (in some special cases).

To help you better decide which shielding gas to use for your welding projects, here is a list of shielding gases that are generally used for different metals:

Non-Ferrous Metals:

For non-ferrous metals like nickel alloys, aluminum, or copper, the best shielding gas to use is:

  • Argon
  • Argon + Helium


  • CO2
  • Argon + Oxygen (2-5%)
  • Argon + CO2 (5-25%)

Applications of MIG Welding

MIG welding is widely used for DIY projects by beginners as well as in industrial sectors. There is a vast variety of modern MIG welders available on the market today. From the best beginner MIG welders to industry-level MIG welding machines, you can find the best choice for you right here on WELDINGRAGE.COM.

However, note that MIG welding is primarily used for squirting metal. Also, you cannot expect to produce the best welds from the very first day. Keep practicing on your ideal welding machine and you will rock!

In case of further questions or suggestions, feel free to leave a reply or contact us.

Thank you!

Leave a Comment