What is the Difference Between MIG and MAG Welding?

FANUC R2000ib 125L R30ia Motoman MA1400 FANUC M710ic 50 Motoman HP6 NX100 FANUC Arcmate 120ic
Welding is one of the most common applications for industrial robots. Nearly fifty-percent of all active industrial robots are used to automate arc welding and spot welding processes. There are several types of robotic arc welding methods, but one of the most common is GMAW (Gas Metal Arc Welding). It can be automated with welding robots such as the FANUC Arcmate 120ic or Yaskawa MA1440. GMAW involves using an electric arc between a consumable wire electrode and base metals. The arc melts both the filler wire and base metals forming a weld. Shielding gas is needed for this process in order to protect the weld pool. GMAW can be categorized into two different processes; MIG (Metal Inert Gas) and MAG (Metal Active Gas) welding.


  • Shielding Gas - The type of shielding gas used is the main difference that separates MIG welding robots from MAG welding robots. MIG welding robots use inert gas as the source for protecting the weld pool. These may include nitrogen, argon, helium, or a mixture of those gases. MIG welding only uses inert gas for shielding. The advantage of inert gas is that it remains intact preventing the intrusion of chemical elements of the gas into the weld bead. This ensures pure welds as the inert gas cannot change the composition of the weld. For those wanting to ensure weld beads remain unaltered, using the FANUC Arcmate 100ic or a similar robot for MIG welding would be best.

    MAG welding uses an active shielding gas instead of an inert gas, these include oxygen and carbon dioxide. Shielding gas for MAG welding can also be composed of a mixture of active and inert gases. For instance, the ABB 1600 may use a combination of carbon dioxide, oxygen, and argon to protect the weld pool from contamination. Since active gas is used, the chemical composition of the weld bead can become altered. Chemical elements of active gases can breakdown with high heat, mixing into the weld bead. For some this is undesirable as the weld will not be pure, however, there are some instances in which altering the composition of the weld bead is helpful.

  • Metals - Both welding methods also differ on the types of metals they can weld. MIG welding is preferred for non-ferrous metals. The Motoman MA1400 with Fronius CMT 3200 can weld aluminum, nickel, or copper using the MIG welding method.

    MAG welding is best for ferrous metals. These include carbon steel, stainless steel, cast iron, and mild steels. The FANUC Arcmate 120ic/10L with Lincoln Powerwave i400 is ideal for welding steel or other ferrous metal workpieces using the MAG method.

  • Cost - Cost is another differentiator between MIG and MAG applications. Cost differences are due to the types of shielding gas used in each welding process. MIG applications are less economical since inert gases can be expensive. MAG welding is the more cost-effective method since active shielding gases are inexpensive.

    While both MIG and MAG welding share many similarities as they are both robotic GMAW processes, there are some key differences that determine the best application of each method. Understanding these differences can help robot users determine which process will be suitable for their metal fabrication needs.

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