MIG welding

 MIG Welding or Metal Inert Gas Welding

● It is also referred as Gas Metal Arc Welding [GMAW].

● It is an arc welding process in which the electrode is a consumable bare metal wire and shielding is accomplished by flooding the arc with gas.

● The bare wire is fed continuously and automatically from a spool through the welding gun.

● The combination of bare electrode wire and shielding gases eliminates the slag covering on the weld bead and precludes the need for manual grinding and cleaning the slag.

● The wire diameter range from 0.8-6.4 mm are used in GMAW.

● The size depending on the thickness of the parts being joined and desired deposition rate.

● Gases used for shielding include argon and helium.

● Selection of gases depending upon the metal being welded, as well as other factors.

● In arc welding, the electrical energy is converted into heat energy.

● Inert gas used for welding aluminium alloys and stainless steels, while CO₂ is commonly used for welding low and medium carbon steels.

Advantages:

● The flux is not required hence no slag formation

● High welding speed.

● Increased corrosion resistance.

● High economy.

● Easily automated welding.

● Welds all metals including aluminium and stainless steel.

Disadvantages:

● Equipment cost is high.

● Not suitable for outdoor work as the strong wind may break the shielding gas.

Applications:

● Used for welding carbon and alloy steels, stainless steel, copper and aluminium alloys.

● With special techniques [pre-heating and post-heating] can be employed for welding cast iron, titanium and other refractory materials.

● MIG welding has been widely used in air-craft and automobile industries.

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