How Does A MIG Welder Work?

how mig welders work

MIG welding is a form of arc welding involving metal and inactive gases used to join two separate steel or aluminum pieces together using the transfer of heat. MIG stands for Metal Inert Gas. The process is sometimes referred to as GMAW in some circles, which stands for Gas Metal Arc Welding.

There are three things that need to be present for a weld to be considered MIG:

  1. An electrode to fill the joint between the two pieces of steel or aluminum to be connected.
  2. A source of power, typically a relatively stable and high-voltage power source to run a welding device.
  3. A shielding gas that works to protect the welds from getting into contact with airborne contaminants and dust.

Let’s take a deeper look into how MIG welders work, to better understand the mechanisms being manipulated and modified to join two pieces of metal into one uniform weld.

How MIG Welders Work

The processes of MIG welding is regarded as a semi-automatic process, as the outcome of a weld relies partially on the skillset of the operator to regulate the amount of welding being performed. This doesn’t mean that an unskilled welder is incapable of operating a MIG welder. After all, the process is relatively simple as far as ensuring the right settings: Set the voltage and use the right electrode. The skill level truly comes in with the quality of the weld. This is where the professionals are separated from the amateurs.

A MIG welder works by transferring the metal wire being used to the joint between the two pieces of metal (aluminum or steel). There are four ways to accomplish this process: globular, pulsed spray, short circuit, and spray:

  • In globular transfers, the welding material transfers across the arc weld in larger droplets. Generally, these droplets are larger than the diameter of the electrode being used in the MIG welding process.
  • In pulsed spray transfers, the power supply cycles between high spray transfer currents and lower background currents. This allows for super-cooling of weld pools in the background cycle.
  • In short circuit transfers, the electrode touches the metal and short circuits. This causes the metal to transfer as a result of the short. This typically occurs between 20 and 200 times per second.
  • In spray transfers, tiny molten droplets of super heated metal are sprayed across the arc. This works similar to the spray that comes out of a garden hose when the opening has been restricted.


how mig welder works

Let’s dive a little bit deeper into the three requirements necessary to form a MIG weld as outlined above:

MIG Welding: The Electrode Wire

Electrode wires used in MIG welding depend on the types of materials to join. While some welds come with the wire and flux fused together, others require feeding of the wires through a nozzle as you pull the trigger through the process. This is basically how a MIG welder spits molten metal out to weld two pieces of steel or aluminum together.

Setting up this electrode requires that the user begins an  arc by clamping it to the welding project, though. The metal is then held inside the welder itself, as MIG welding is classified as wire-feed type welding. Then, MIG welders allow users to adjust feed rates of wires. For this reason, users should first perform a test bead on a scrap piece of metal. This allows fine tuning of feed rates for the strongest results in the final weld. The most common electrode thicknesses for MIG welding work ranges between 0.023″ and 0.045″. However, some are thicker than this, especially if being utilized for heavy-duty or industrial applications.

MIG Welding: The Shielding Gas

There are two possible shielding gas sources in MIG welding:

  • The shielding gas can originate from chemical reactions in flux, or
  • The gas could come from a tank connected to the welder

The main source of the shielding gas in a MIG welder is the connected gas tank, which also contains mixtures of two inert gases: argon and carbon dioxide. This gases come from manufacturers. Yet, the main reason for using inert gases is so the gas doesn’t react with the metal, causing contaminants to compromise the structure and integrity of the weld.

When a user pulls the trigger on their welder, the gases are pumped through the welding cable, coming out the same nozzle where the welding wire is actively fed. Nevertheless, with this, the inert gas combination creates a type of shield, protecting the arc weld.

MIG Welding: The Power Source

MIG welders use DC (direct current) power sources to produce heat. However, how MIG welders work is dependent on the heat settings chosen. Yet, several voltage selections exist for users to select the option that will produce the best weld based on their needs. If a user selects a heat setting that is too high, they might find themselves with a burnt or unusable weld. This shouldn’t discourage these users, though. Even the most seasoned welding professionals make mistakes. Finally, these adjustments in heat rates for MIG welding power sources are made through modification of voltage rates to meet specific welding needs.

Looking to compare MIG welders? We feature six of the highest rated and best power-to-dollar ratio MIG welders on the market:

Millermatic 211 Review

millermatic 211 review

Miller Electric has long been known as a top of the line manufacturer for professional and amateur level welding machines. The Millermatic 200 is one such product from Miller Electric that has proven true to this credo. This is a likely top contender if you are a welder looking for a portable, lightweight MIG solution that still packs a serious punch. For more information, continue reading the Millermatic 211 review below.

It is no secret that Miller Electric has established itself as an authority in the manufacture of welding machines. The company’s long-standing solid reputation in the welding industry alone is enough to guarantee the proper tool for the job. Amateur and professional welders alike can agree that Millermatic is one of the most reliable brands in the MIG welding industry. The Millermatic 211 made our list of six best MIG welders, and with good reason. Read on for more.

millermatic 211

Millermatic 211 Review

The MIG Millermatic 211, from Miller Electric, is a rectangular steel MIG welder. It weighs approximately 48 pounds, and welds aluminum, milder steels, and also stainless steel. For aluminum welds, the Miller 211 is capable of welding 18 gauge-3/8”, and 24 gauge -3/8″ for a thinner steel materials. The thickness of stainless steel material, on the other hand, can be up to 20 gauge -¼”. According to one Miller 211 review, the welding capabilities of this machine are far above the ratings given by Miller Electric, which is a good thing. For instance, although the material thickness rated for a mild steel is only up to 3/8”, it is possible to weld a 1/4” sheet of steel on the 240V setting. This is the equivalent of “overclocking” a computer, but for a MIG welder.

The following items come with the package:

  • 10ft M-10 MIG welding gun
  • 10ft work cable with a clamp
  • Built-in gas solenoid valve
  • Dual gauge regulator with gas hose

Buyers also receive two sample spools of 0.03 inch solid wire, two contact tips and two hook-and-loop cord wraps. Working with the Millermatic 211 MIG welder requires adherence to the width, thickness and height standards of materials being welded. The overall width of material thickness gauge is 20 – ½” while the CSA certified overall height is 12- ½”. One Millermatic 211 review reveals the superb performance of this welder on all the materials with varying thicknesses. The review states that it is indeed a portable workhorse and absolute power player.


Auto-Set Features in Millermatic Welders

One of the most outstanding features of the Miller 211 MIG welder is the Advanced Auto-Set. This feature is a breakthrough control that automatically sets the welder to the proper parameters. All a user will need to do is set the diameter of the wire and the material’s thickness, and they are ready to start welding. According to one Millermatic 211 review, this feature makes it simple for rookies to use the product, much more so than alternatives that do not have the Auto-Set capabilities.

The other feature is Auto Spool Gun Detect, which allows the operator to pull the trigger on the MIG gun, spool gun or push/pull gun. This feature also automatically detects and recalls the voltage, wire feed speed, and timer of the active gun. The Miller 211’s smooth start feature creates a smooth arc with minimal residual molten metal spatter.

millermatic 211 review

Additional Features of the Millermatic 211

A substantial number of comments in the Miller 211 review agree that the angled cast aluminum drive system in the Millermatic MIG welder is a great addition. It creates consistent feeding and easy setup for up to 15ft MIG spool guns. The welder’s Quick Select Drive Roll feature enhances the convenience of using the Miller 211. This feature it makes setup quicker by providing three grooves–one for the flux cored wire and two for different sized solid cables. The welder also comes with best in class thermal overload protection and Fan on Demand features.

The Miller 211’s input voltage ranges between 120 and 240V for AC power. According to one Miller 211 review, the stability of its performance on the 120V is quite impressive on a range of steel and aluminum thicknesses. Its power output ranges from 30 to 230A for DC power, and the welding processes comprise of both MIG and Flux Core. Its handheld portability makes it quite usable in a wide range of applications, including maintenance, repair, auto/cycle shops, farm and ranch jobs and hobby welding.

miller 211 review

Pros and Cons of the Millermatic 211

The Millermatic 211 has a wide range of applications. Dollar for dollar, based on the features provided by this welder, it is one of the best on the market. Its durability and performance are worthy of the name that Miller has worked hard to build over time. You can’t help but note the lightweight feature, despite the fact that it is made from thick, durable steel. Its portability makes it easy for one to carry around for traveling jobs. The Millermatic 211’s cutting-edge technology allows for the reduction of spatter. Miller Electric’s rebate program is another significant advantage that is quite a relief on the Millermatic 211’s price. This welder is easy to use and user-friendly to the rookies in welding works.

The only drawback, according to one Millermatic 211 review, is that welders need to remain extremely alert regarding welder quality. Whether you are buying it from an online seller or a brick and mortar store, you should test to confirm that the welder you are buying is free from faults.