MAG welding—the standard process for steel—is cost-effective, fast, and requires little rework. This is because the process combines high deposition rates with consistent weld quality and can be used very effectively in both manual and automated applications. This makes it particularly well-suited for companies that want to weld steel components reliably, productively, and with repeatable results.
What is the MAG welding process?
The MAG welding process—short for metal-active gas welding—is a type of gas-shielded welding that uses a highly reactive active gas. A consumable wire electrode serves as the filler material, melting away in the arc and forming the weld joint together with the base metal.
As an arc welding process, metal-active gas (MAG) welding is designated as process number 135 according to DIN EN ISO 4063 and is considered easy to learn and cost-effective. Because MAG welding produces very little slag, rework is generally minimal and weld quality remains high.
Here's what happens during MAG arc welding
In MAG welding, an arc burns between the solid wire electrode and the workpiece, creating a molten pool. A welding power source supplies the current, while the wire feeder continuously feeds the welding wire through the welding gun.
The welding parameters—voltage, current, arc length, and wire feed speed—together with the wire diameter, determine the deposition rate. At the same time, they influence how stable the arc burns, how deep the penetration is, and how uniform the weld bead is. For example, if the wire feed rate is too high or the voltage is too low, the arc can become unstable. If, on the other hand, the values are well-balanced, a controlled molten pool with a clean weld bead formation results. This is precisely why the correct adjustment of these parameters in MAG welding is so important for productivity, spatter formation, and weld quality.
However, without the proper gaseous shield, this molten pool would oxidize immediately, which is why the shielding gas used is a decisive factor in the weld and its quality.
Shielding Gas in MAG Welding—Here's Why It's So Important
In MAG welding, an active shielding gas surrounds the arc and protects the weld pool from oxygen and oxidation. Depending on the application, pure carbon dioxide or argon mixtures containing an active component of carbon dioxide or oxygen are used. Carbon dioxide acts as a reactive gas that deepens the penetration while simultaneously stabilizing the weld.
In practice, MAG welding typically uses argon mixtures containing carbon dioxide or oxygen as the active gas. The high argon content ensures a stable arc and reduces spatter compared to pure carbon dioxide, while the active gases control arc stability and penetration behavior. The correct amount of shielding gas maintains consistent gas coverage, thereby contributing to high productivity and weld quality.
It is precisely this active shielding gas that distinguishes MAG welding from its inert counterpart, MIG welding.
What is the difference between MIG and MAG welding?
MIG and MAG welding differ in the type of shielding gas used: MAG uses an active gas, while MIG uses an inert gas. Both are forms of metal inert gas (MIG) welding with a consumable wire electrode, but because of their different gas requirements, they are suitable for different materials and applications.
The difference between MIG and MAG can be identified primarily by three characteristics related to the gas, the material, and the application:
| Characteristic | MIG Welding | MAG Welding |
| Inert gas | inert (argon, helium) | active (CO2, argon mixture) |
| Materials | Aluminum, copper, non-ferrous metals | Steel, structural steel, low-alloy steels |
| Deployment | Non-ferrous metals | Steel Construction, Mass Production |
Typical Applications for MAG Welding as a Standard Process
MAG welding is considered the dominant process in steel construction and is used wherever steel components need to be produced and joined in large quantities in a cost-effective manner. One reason for this is the high degree of automation, which makes the process the standard in mass production.
Typical applications for MAG welding include vehicle manufacturing, the automotive industry, plant engineering, and general metalworking. Whether thin sheet metal or load-bearing structures, the MAG welding process offers a versatile way to join steel, requiring minimal rework and delivering high productivity.
Is MAG welding suitable for chromium-nickel steels?
MAG welding can be used not only for plain steels but also, with special gas mixtures, for chromium-nickel steels and stainless steel. For materials such as aluminum, copper, or titanium, however, companies more often use the MIG or TIG processes, as these are better suited for such applications.
One thing is certain: As broad as the range of applications may be, MAG welding in industrial settings consistently requires the proper protection for the welder.
Protective Equipment for MAG Welding
MAG welding requires appropriate protective equipment because noise, flying sparks, and welding fumes pose hazards that are often underestimated. A welding helmet, gloves, and flame-resistant protective clothing protect the MAG welder personally, while an extraction system captures and reliably removes the welding fumes produced. Since flying sparks can cause fires in the worst-case scenario, fire safety measures in the workplace are also mandatory.
Standard Processes with New Standards: MAG Welding with Schnelldorfer Maschinenbau
Schnelldorfer Maschinenbau has been developing welding equipment and systems for MAG, MIG, TIG, and laser welding for over 40 years. At our modular welding systems Every component is perfectly matched to the others—and to ensure this, we precisely tailor the welding power source, wire feed, and shielding gas flow to your specific steels and welding parameters, from single welds to automated mass production. Because one thing is certain with us: Together with you, we’ll find the welding process that’s right for your production.
Contact us today and see for yourself. We look forward to hearing from you!
Frequently asked questions (FAQ)
Why is MAG also called "Method 135"?
The designation 135 is derived from DIN EN ISO 4063 and describes metal-inert gas welding with a solid wire electrode. This standard ensures a clear technical classification.
Can MAG welding be used with steel?
Yes, MAG welding is very well suited for steel, especially carbon steel, structural steel, and low-alloy steels. The active shielding gas improves penetration in these materials, making the process highly versatile for use with various types of steel.
What is MIG welding, or metal-inert-gas welding?
MIG welding, or metal-inert-gas welding, uses a chemically inert shielding gas such as argon or helium. Because the inert gas does not react with the molten pool, this method is suitable for aluminum, copper, and other nonferrous metals.
When to use MIG and when to use MAG?
MIG is used for non-ferrous metals such as aluminum, while MAG is typically used for steel. The choice between MIG and MAG therefore depends on the base material.
What are the three types of welding processes?
The three main welding processes are MIG, MAG, and TIG. MIG and MAG use a consumable wire electrode, while the TIG process uses a non-consumable tungsten electrode. All three use shielding gases.
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