MIG/MAG Welding

MIG Vs. MAG Welding

Table of Contents > 1. Explaining Active Vs. Inert Shielding Gas Variants For MIG And MAG Welding
2. Switching From MIG Welding To Mag Welding: The Deeper Penetration Solution
3. Learn Why MIG Welding Is More Straightforward
4. Battle Of The GMAW Titans: Is There A Winner In the MAG Vs. MIG Welding Contest ?
5. Wrapping Up The Discussion: MIG And MAG Techniques Are Utilized In Tandem
6. MIG Vs. MAG Welding - FAQ

Two of the more prevalent welding techniques are being put under the critiquing lens in this process comparing post. The first is MIG welding, a method that relies heavily on an inactive shielding gas. That gas is there to block the atmospheric effects of air. MAG (Metal Active Gas) equipment rigs, on the other hand, employ a gaseous compound that imparts an active component to the welding process. It’s right there, in the middle letter, the ‘A’ for active.

When talking of the two techniques, things tend to get a little confusing. Technically, they’re both referred to as GMAW (Gas Metal Arc Welding) methods, and they’re both very popular, but the two techniques do have differences that set them apart. In this post, then, the key differences between the two techniques will be discussed in some detail. Further, a selection of compatible Tooliom products will be covered in this article, the better to ensure a perfect equipment match for our shoppers.

GMAW process

GMAW process


Let’s open this post with that one defining difference between the two GMAW welding techniques, the gas, whether it be inert or active.

Explaining Active Vs. Inert Shielding Gas Variants For MIG And MAG Welding

If a beginner finds the process differences confusing, look again at the middle letter in the abbreviated names of the welding techniques. The ‘I’ is for inert, and the ‘A’ is for active. This means an equipment purchase like the Tooliom MIG/Stick/TIG Multi-Process Welder TL-135M needs a bottle of inactive gas. A 100% argon mix is often recommended. The role the gas takes on is that of an atmospheric shield. Without this shielding gas, the oxygen and nitrogen in the air would cause a number of weld-inhibiting problems.

MIG/Stick/TIG Multi-Process Welder TL-135M 3 in 1 IGBT DC Inverter|Tooliom

MIG/Stick/TIG Multi-Process Welder TL-135M 3 in 1 IGBT DC Inverter|Tooliom

Moving on to MAG welding, a pure shielding gas is no longer adequate. The 100% argon cylinder is switched out for an active gaseous mix. For example, a carbon dioxide and oxygen mix or a carbon dioxide and argon and oxygen mix. Both of these gas blends are acceptable, as are other popular mixes. A little basic chemistry knowledge will go a long way when working with these active shielding gases. That’s because blends are sometimes annotated on the equipment bottles in scientific shorthand. A CO₂ + O₂ + Ar blend indicates that carbon dioxide (CO₂) and oxygen (O₂) and argon (Ar) are all present.

Active gas bottles for MAG welding equipment don’t just add active/inactive gas mixes. No, they also include percentile mixes. Like a chemically active recipe, numerical measures are placed in front of the elemental codifiers. Here’s a prime example of a real world argon-based active shielding gas: C25, which is a mix of 75% argon and 25% CO₂. Typically, as per the last example given, argon is the dominant gas in the mix. If MAG welders want to know more about this fascinating topic, they can do an internet search on active, argon-based shielding gases.

Mixture Shielding Gas of 75% Argon and 25% CO₂
75% argon and 25% carbon dioxide mixture shielding gas

Source: https://yeswelder.com/blogs/yeswelder/shielding-gas-for-mig-welding


Switching From MIG Welding To Mag Welding: The Deeper Penetration Solution

If a seasoned welder is working on a construction project, the weld pool they’ve created with their equipment is clean and free of the effects of atmospheric contamination. There’s no spatter, no workpiece porosity issues, and no problems with arc stability. Every details seems just right. The weld bead is pooling and melting and thermal transfer ratios are high.

So why even bring in a substitute gas mix? Why switch from a single inert shielding gas to a mix of three or more gases? It’s all about weld penetration. Imagine a thicker piece of steel. The root joint has been cleaned and prepped just so, but a MIG welding process has been vetoed. A bottle of 80%Ar + 20%CO₂ has been piped into the equipment feed. When the melt pool forms now, it penetrates deeper into the root.

Weld penetration comparisons in weld cross-sections made with several shielding gases.

Weld penetration comparisons in weld cross-sections made with several shielding gases.

Source: https://www.sciencedirect.com/topics/engineering/shielding-gas

Depending on the base metal and the thickness of that workpiece, slightly different active shielding gas recipes can be sourced to tune the process. They alter the weld profile in such a way that it changes to suit the process. Spatter rates, penetration depth, and arc stability characteristics, all vary as this gaseous formula varies. This is probably why, although an active gas can be 100% pure CO₂, a completely argon-less mix isn’t desirable. Granted, CO₂ shielding gases provide super-deep penetration, but the joint loses the benefits associated with an argon-rich blend. The weld will likely be aesthetically unappealing because of the presence of bead spatter.

different shapes of welding beads
Different proportions, different shapes of welding beads
Source: https://www.mig-welding.co.uk/forum/threads/custom-gas-mix.1944/

In real-world applications, then, argon is the inert component in the compound. Adding carbon dioxide and/or oxygen into the mix, the shielding gas gains its active characteristics. It’s these mixes that find themselves in common use in thick mild, or stainless steel welding projects.

MAG Welding Advantages

  •   Deeper penetration of weld bead in thick ferrous metals
  •   Reduction of spatter ensures less post-work downtime
  •   A matching increase in weld quality due to absorption of active gases
  •   Tends to deposit weld bead faster, leading to quicker steel welding
  •   MAG welding techniques are popular in mild and stainless steel work

Popular for dense steel welding projects, active gas welding also breaks down under the intense heat generated by arc energy. The inert argon functions as intended, as an atmospheric shield. As for the carbon and oxygen, it’s absorbed by the weld pool to add intended mechanical and chemical properties to the final weld. Porosity elimination and joint strength are two of the most desirable features added.

Do note, if someone lacks knowledge of this welding technique, they can end up adding, or subtracting, joint strength because they’ve matched the wrong active gas formula for the selected base workpiece metal type.


Suitable for Metal and Applications of GMAW Shielding Gases
Suitable for metals and applications of GMAW shielding gases

Source: http://www.halversoncts.com/711-gmawfcaw-shielding-gases.html

Learn Why MIG Welding Is More Straightforward

Simpler approaches tend to yield more predictable outcomes. Perhaps that’s why active shielding gas blends require more planning before they can be employed on a project. If the percentage of active elements present in a shielding gas blend is released, then too much carbon or oxygen could be infused within the weld pool. Subsequently, unintended consequences are possible because this is a reactive process. Opting instead for a bottle of pure argon, the possibility of such consequences is remote; there are no reactive elements to impact the weld bead when the shielding gas is totally inert.

That’s all well and good, but is gas purity really enough to justify process selection? For one thing, argon gas cylinders can be prohibitively expensive, but that’s the preferred shielding medium for MIG welding equipment. Its proper use results in clean and slag-free weld seams. Interestingly, however, cylinders containing reactive mixes are a better choice when ferrous metals are the job subject. This was mentioned earlier in this post when MAG welding was discussed. This leaves MIG-configured equipment the preferred selection for non-ferrous work.

Ferrous VS Non-Ferrous Metals

Ferrous Vs. Non-Ferrous metals

For aluminum alloys, copper, and even titanium, MIG settings are locked into the welding equipment, and a cylinder of pure argon is purchased. Expensively or not, some of these iron-free metals are very chemically reactive when they’re exposed to a super-heated welding arc. If oxygen or carbon is added, even in the minutest amounts, the quality of the weld could be jeopardized.

Imagine an aerospace facility. An aircraft frame in this specialized industrial complex needs hundreds, perhaps thousands of welds. Unlike a commercial, industrial project, there’s not much steel in the mix. It’s a relatively heavy metal, and therefore not desirable in aircraft frames. Titanium and aluminum, on the other hand, and alloys thereof, are used in great quantities throughout the aerospace sector. The same applies to the shipbuilding industry. Actually, both MIG and MAG configured equipment rigs are common here, for ships use both steel and aluminum. More accurately, steel is used in large vessel construction, while aluminum is the go-to metal in smaller ships.

Ship Welding

 Maritime welding

Source: https://auto.edu/blog/what-is-maritime-welding-important/

Either way, the correct selection of the right shielding gas is essential when setting out to use a MIG welding machine.  That ‘I’ for inert cannot afford to be proven a lie by introducing a reactive element into the gas mixture.

Battle Of The GMAW Titans: Is There A Winner In The MAG Vs. MIG Welding Contest ? 

To be realistic, there is no real MIG Vs. MAG fight to resolve. Both techniques are similar. They both require shielding gases, both feed a consumable wire electrode into the weld pool, and they both employ nearly identical machine types. In fact, some MIG welding machines can be tuned on their control panels so that they function as MAG machines. 

Setup mig welder

Setup mig welder

Source: https://yeswelder.com/blogs/yeswelder

If a stainless steel workpiece is thick and pool penetration problems seem likely, the MAG setting is the logical fit for the project. Of course, a cylinder of active oxygen or argon carbon dioxide would be fitted when this setting was chosen. Now, would it be possible to use MIG settings and a cylinder of argon? It’s not an ideal scenario, not unless the welder has no other choice. Ionization issues and thermal conductivity problems are going to occur if argon is the shielding gas on a steel workpiece. Think about that if tempted to use the wrong gas. 

Ideally, MAG machines or MIG equipment with a MAG setting must be utilized when working with steel. The active gas assures deeper root penetration and a stronger weld joint. For non-ferrous work, the welder instead chooses MIG welding gear plus a cylinder full of inert gas. Bucking this rule, pure CO₂ is another option. However, this is a reactive gas, one that produces some spatter, too. Even so, it’s a cost-efficient solution for projects that don’t need an aesthetically pleasing finish. On the upside, CO₂ shielding gases deliver deep bead penetration into thick metal joints. For that aforementioned downside, shoddy welds require post-work treatment, which typically amounts to more downtime before the job can be posted as complete.

Weld beads obtained by using different contents of CO2 in Ar based shielding gas.

Weld beads obtained by using different contents of CO2 in Ar based shielding gas.

Source: https://www.researchgate.net/figure/Weld-beads-obtained-by-using-different-contents-of-CO2-in-Ar-based-shielding-gas-GMAW_fig12_267142611

Wrapping Up The Discussion: MIG And MAG Techniques Are Utilized In Tandem

That’s true. The equipment forms and/or settings both have their place. They also have more similarities shared between them than differences. Ultimately then, it’s up to the welder and the project base metal. Steework is common, used as it is in everything from the construction industry to commercial pipework, so MAG equipment settings are going to dominate, along with cylinders of active carbon/oxygen and proportional measures of blended argon/helium. Happily, those are cost-effective mixes.

Switching over to MIG welding, perhaps on a Tooliom MIG/Stick/TIG Multi-Process Welder TL-135M, a completely inert cylinder filled with argon is the more probable shielding gas. It’s utilized on non-ferrous metals, which aren’t quite as common as steel alloys. Again, this isn’t happenstance. It’s by design. Argon is chemically unreactive, meaning it won’t impact the chemistry of a thermally susceptible alloy like aluminum.

MIG/Stick/TIG Multi-Process Welder TL-135M 3 in 1 IGBT DC Inverter|Tooliom

MIG/Stick/TIG Multi-Process Welder TL-135M 3 in 1 IGBT DC Inverter|Tooliom

Cracking, warping, oxidization, these and more defects occur on heat-sensitive non-ferrous alloys with worrying regularity. To eliminate the majority of those welding defects, MIG welding and a cylinder of inert gas are both advised. Meanwhile, for deep penetration, high-strength and ultimate resilience, seasoned welding professionals choose MAG welding settings/equipment. That gear is matched to an ‘A’ for an active cylinder injected with carbon dioxide and oxygen into argon. As this mix flows over and around the weld pool, it breaks down. The inert gas shields while the active elements add mechanical and chemical characteristics to the ferrous workpiece weld.

Keep that in mind, beyond penetration depth, active shielding gases do have the potential to impact the final properties of a weld.

MIG Vs. MAG Welding - FAQ

What is the difference between MIG Welding and MAG Welding ?


  • An inert gas such as nitrogen, argon, helium, or a mixture of such gases is used as shielding gas.
  • The shielding gas remains intact during welding (i.e. no disintegration takes place). So it does not induce any external chemical element into the weld bead.
  • It cannot alter the chemical composition of the weld bead or its properties.


  • A mixture of active gas (like oxygen or carbon dioxide) and inert gas (like nitrogen, argon or helium) is used as shielding gas.
  • The active shielding gas disintegrates during welding due to intense heat of electric arc. Thus certain chemical elements (like oxygen, carbon, etc.) are induced into weld bead.
  • It is capable in altering the chemical composition and the concerned properties of the weld bead.

What are the metals suitable for MIG welding and MAG welding ?

  1. MIG Welding is suitable for non-ferrous metals.
  2. MAG Welding is suitable for ferrous metals.

What are the gases that different metals match with ?

Shielding gas or mixture Metals and applications
Argon Virtually all metals except steels.
Helium Aluminum, magnesium, and copper alloys for greater heat input and to minimize porosity.
Ar + He (20-80% to 50-50%) Aluminum, magnesium, and copper alloys for greater heat input and to minimize porosity (better arc action than 100% helium).
Nitrogen Greater heat input on copper (Europe).
Ar + 25-30% N₂ Greater heat input on copper (Europe); better arc action than 100% nitrogen.
Ar + 1-2% O₂ Stainless and alloy steels; some deoxidized copper alloys.
Ar + 3-5% O₂ Carbon and some low-alloy steels.
CO₂ Carbon and some low-alloy steels.
Ar + 20-50% CO₂ Various steels, chiefly short circuiting arc.
Ar + 10% CO2 + 5% O₂ Various steels (Europe).
CO₂ + 20% O₂ Various steels (Japan).
90% He + 7.5% Ar + 2.5% CO₂ Stainless steels for good corrosion resistance, short circuiting arc.
60-70% He + 25-35% Ar + 4-5% CO₂ Low-alloy steels for toughness, short circuiting arc.
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