Introduction:
There has always been a debate about MIG and MAG welding. Some argue that the difference is mainly a matter of terminology—MIG being the preferred term in the U.S. and MAG more commonly used in the UK, much like the differences between British and American English. From this perspective, MIG and MAG are essentially the same process, with only their names setting them apart.
Others, however, point to a more technical distinction: the type of shielding gas used. In this view, the "I" in MIG stands for inert gases, while the "A" in MAG refers to active gases, each influencing the welding process differently.
So, is the difference just a matter of naming, or does it extend beyond terminology? Let’s break it down.
Ending the Debate: MIG and MAG
Wikipedia: “Gas metal arc welding (GMAW), sometimes referred to by its subtypes metal inert gas (MIG) and metal active gas (MAG), is a welding process in which an electric arc forms between a consumable MIG wire electrode and the workpiece metal(s), which heats the workpiece metal(s), causing them to fuse. Along with the wire electrode, a shielding gas feeds through the welding gun, which shields the process from atmospheric contamination.”
Shielding gases are generally divided into two types:
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Inert Gases (e.g., Argon, Helium): Do not react with the weld pool. Common in MIG and TIG welding.
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Active Gases (e.g., CO₂, Oxygen): React with the weld pool to influence weld properties. Common in MAG welding.
What is Shielding Gas?
Shielding gas is a critical component in many arc welding processes. It forms an invisible barrier around the welding arc and molten metal, protecting them from harmful elements in the air like oxygen, nitrogen, and moisture. Without shielding gas, the weld is prone to oxidation, porosity, and other defects that can compromise its strength and appearance.
Shielding gas also helps control the weld penetration profile, which is crucial for achieving proper fusion and strength. Different gases affect how deep or wide a weld penetrates into the base metal. In addition to penetration, shielding gas influences arc stability, filler metal transfer, weld bead shape, and the overall mechanical properties of the final weld.
So, which welding processes use shielding gas?
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GMAW (MIG/MAG)
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GTAW (TIG)
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FCAW-G (Gas-shielded Flux-Cored Arc Welding)
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PAW (Plasma Arc Welding)
Key Differences Between MIG and MAG
| Feature | MIG Welding | MAG Welding |
|---|---|---|
| Shielding Gas | Inert gases (Ar, He) | Active gases (CO₂, Ar+CO₂, or Ar with O₂<5%) |
| Suitable Materials | aluminum, copper, magnesium and titanium. | unalloyed, low-alloy and high-alloy materials |
| Weld Quality | Clean, minimal oxidation | Stronger penetration, but more spatter |
Does Shielding Gas Influence Welding Equipment Selection?
MIG and MAG welding equipment is nearly identical, with minor differences. Both use MIG welding machines that regulate voltage, wire speed, and shielding gas flow to maintain a stable arc. Most components, including welding torches, gas regulators, hoses, and consumables, are interchangeable, with shielding gas being the primary distinction. Multi-process welders often include MIG as an option, covering both MIG and MAG welding.
The Bernard Q400 MIG Gun, manufactured by Vanes Electric, is designed for high-performance welding applications. It is rated at 400A with CO₂ and 350A with mixed gases, offering a 60% duty cycle (6 minutes out of 10) for reliable, continuous welding. As part of MIG consumables, the variable contact tips T-0XX Series support wire sizes ranging from .023" to 1/8", providing compatibility with different welding needs and ensuring reliable performance. Check our Bernard MIG gun parts page to choose the right accessories for your application.
FAQs
Q: Can I use a MIG gun without shielding gas?
A: Yes, you can, but you need to use flux-cored wire instead of solid wire（FCAW-S). Flux-cored wire generates its own shielding gas, protecting the weld pool from contamination. Ensure you select the right flux-cored wire for your application and adjust the machine settings accordingly.
Final Thoughts
MIG and MAG differ in shielding gas composition, not just terminology. MIG uses inert gases like argon and helium, making it suitable for non-ferrous metals. MAG, on the other hand, relies on active gases like CO₂ or O₂ mixtures, commonly used for ferrous materials. Despite these distinctions, the industry often refers to all GMAW welders as MIG welders, causing confusion. Recognizing these differences helps ensure the correct welding process is used for each material.
