MIG Welding | What is MIG Welding and How Does it Work?

What is MIG Welding and how does it work? MIG Welding or Gas Metal Arc Welding (GMAW) is a relatively new type of welding technology. MIG welding was developed in the 1960’s by General Electric Company. Since then, this method of welding has gained popularity due to its ability to produce high-strength, defect free welds that don’t require post-weld cleaning. 

It is particularly useful for joining materials that are difficult to weld, such as stainless steel, aluminum, copper, brass, bronze, nickel alloys, titanium, zirconium, and cobalt.

MIG Welding Equipment

What is MIG Welding and How Does it Work?

The MIG welding process consists of three basic components: power supply, welding torch, and consumables.

Power Supply

A power source supplies electricity to the welding system. There are several types of power sources available including direct current , alternating current and pulsating DC.


A welding torch is the device that transfers energy from the power source to the welding operation. Torches come in several sizes and shapes. The most common torches include stick, hand held, gas shielded, and wire feed.


These are the items used during the welding process. They include flux core wires, filler metals, shielding gases, and consumable tips.

Welding Equipment

There are many different types of equipment used for metal inert gas welding. These can be divided into two categories: stationary equipment and portable equipment. Stationary equipment includes welding machines, welding robots, welding booths, and other similar pieces of equipment. Portable equipment includes handheld welding tools, welding guns, welding helmets, welding shields, and welding gloves.

Stationary Equipment

Welding Machines

A welding machine is an apparatus designed to perform one or more welding operations on material. A typical welding machine will have a power source , a control panel with controls to operate the machine, and a work area where the welding takes place. Some welding machines also have a cooling unit which helps keep the welding electrodes cool.

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A robot is a piece of automated machinery that performs repetitive tasks automatically. Robots are often used for welding because they can move quickly and accurately over large areas.


A welding booth is a room that houses the welding machine and provides protection from sparks and hot particles. It may also contain a shield that protects the operator from the heat and fumes created during the welding process.

Other Equipment

Additional equipment is needed to run a successful welding job. This equipment includes welding cables, hoses, clamps, fixtures, and other miscellaneous items.

Portable Equipment

Handheld Welder

A handheld welder is a small, lightweight tool that allows you to weld without having to set up your own welding rig. Handheld welders are typically powered by batteries.


A gun is a handheld welding tool that uses compressed air to propel a stream of molten metal out of the tip. Guns are usually equipped with a nozzle to allow the user to adjust the size of the arc.


A helmet is a protective headgear worn while performing welding operations. They help reduce the risk of injury by protecting the eyes, ears, face, neck, and head from flying debris.


A shield is a device that covers the welding area to protect the person doing the welding and those around them. Shields are made of materials such as rubber, plastic, glass, or stainless steel.


Welding gloves are specially designed for use when working with welding equipment. They provide protection against burns, cuts, and electrical shock.

Flux Core Wire

Flux core wire is a type of welding wire that has a coating of flux applied to it before being fed through the welding gun. Flux core wire is used primarily for joining dissimilar metals.

Metal Inert Gas Welding Process

The MIG welding technique is commonly referred to as Metal-Inert-Gas . MIG welding is a method of welding using a combination of a filler rod and shielding gas. The filler rod is composed of either pure metal, alloy or mixture of both. The shielding gas is used to prevent oxidation of the base metal and the filler metal and to produce an extremely clean weld.

The MIG welding process produces the best quality welds for most applications. It can be used in many different types of materials including mild steel, stainless steel, aluminum, and other metals.

Welding Gun

A wire feeder is used to supply a constant source of wire to the welding gun. The wire feeder uses current along with the force of gravity to push wire to the welding gun. The welding gun is sometimes referred to as a stinger. The stinger contains a short length of copper tubing where the filler wire is held. The wire feeder pushes the wire into the copper tubing. The copper tubing directs the wire to the tip where an arc is generated.

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The welding gun also contains a contact tip that is designed to maintain a constant electric arc. The arc melts the electrode wire, which melts the material to be welded, and joins the two pieces together. The shielding gas is a mixture of argon and carbon dioxide.

Shielding Gases

The shielding gas is injected into the weld area during the welding process. The shielding gas protects the weld area from air contaminants, contaminants from the welding wire, and contaminants created by the heat of welding. The shielding gas can be introduced through the welding gun or it may be introduced through an outside source.

Shielding gases provide several advantages.

  • First, the gas protects the weld area from air contamination.
  • Second, the gas protects the weld area from contaminants from the welding wire.
  • Third, the gas protects the weld area from the heat of welding.

The shielding gas also cools the weld area. As the shielding gas is injected into the weld area, it cools the weld area. The cooling of the weld area increases the weld quality. The shielding gas also protects the weld area from oxidation.

As the gas is injected into the weld area, it displaces the oxygen in the weld area. The displaces oxygen protects the weld area from oxidation, which protects the weld area from cracking. The gas protects the weld area from oxidation by displacing the oxygen. The oxygen in the air reacts quickly with the metal during the welding process.

The oxygen forms oxides and the surface of the metal becomes oxidized. The shielding gas displaces the oxygen and prevents the formation of oxides.

MIG Welding Without Gas

You can also MIG weld without the use of a shielding gas, this process is know as flux core MIG welding.

Flux core MIG welding is a type of welding that uses a continuously fed electrode wire that is coated with flux. This flux serves several purposes, including shielding the weld pool from atmospheric gases, stabilizing the arc, and providing a source of deoxidizers and alloying elements. Unlike traditional MIG welding, flux core MIG welding does not require an external shielding gas to protect the weld from oxidation.

Voltage and amperage

The amount of voltage and amperage required for a weld is determined by a variety of factors, including metal thickness, metal type, joint layout, welding location, shielding gas, and wire diameter speed (among others).

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Another factoris the type of welding equipment being used. When choosing a welder, you should determine what kind of welding equipment will be needed.

When selecting a welder, you must consider your needs. You need to know how much voltage and amperages you will require. If you do not have enough voltage and amperages, then you might want to look at purchasing additional equipment as welder that does not have enough voltage and/or amperages could cause damage to your equipment.

It is important to understand how much voltage and amperes a particular welder requires for possible applications before acquiring one.

Summary – What is MIG Welding?

The MIG welding process produces an extremely clean weld with the process often producing the best quality welds for most applications. It can be used in many different types of materials including mild steel, stainless steel, aluminum, and other metals. 

The process itself can be learned through a number of courses that are available in most countries. An example of the teaching components can be found here although obviously each course and college will vary.

Further Reading