MIG Welding: Principle, Work, Equipment's, Disadvantage

Metal inert gas welding (MIG)

 

MIG welding 

MIG Welding is an arc welding process wherein coalescence is produced by heating the job with an electric arc established between a continuously fed metal electrode and the job.

 

 No flux is used but the arc and molten metal are shielded by an inert gas, which may be argon helium is CO.

Before igniting the arc, gas and water flow are checked. Proper current and wire Fedwire-feed speed is set and electric connections are ensured. Mig welding is an automatic or semi-automatic process in which wire connected to a source of direct current acts as an electrode to join 2 pics of metal as it continuously feeds through a welding gun. The inert gas acts as a shield, keeping air-born contaminants away from the weld zone. The arc is produced between the electrode and continuously feed metal wire real which melts for continuous welding process for large-size welding w/p.

 

MIG Welding Construction and Working 
 

It consists of a welding power source and cables rated at 400 Amps. The major types of power sources arc DC generators as Ac transformers with rectifiers.

The welding torch energies the electrode, feed the electrode, and the shielding gases. The Torch may be air-cooled or water-cooled.

The Wire feed mechanism may deliver electrodes to the torch at a construct speed or at different speeds.

The function of shielding gas is to protect molten metal and the electrode end against atmospheric contamination.

MIG WeldingWorking:

 

Before igniting the arc, gas and water flow are checked proper current and wire feed speed is set and electrical connections are ensured. Current and shielding gas flow is switched on and the electrode is scratched against the job as usual practice for striking the arc.

About 15 mm length of the electrodes projected from the torch before striking the arc. During welding, the torch remains about 10-12 mm away from the job, and arc length is kept between 15 to 4 mm.

 

MIG Welding Advantage

1)    Because of the continuously fed electrode. The MIG welding process is much faster as compared to Tig Welding.

2)    Tig can produce jointly with deep penetration.

3)    Thick and thin both types of w/p can be welded effectively.

4)    The process can easily mechanized.
5)    High ARC travel speeds associated with Mig welding reduce distortion considerably.

 

MIG Welding Disadvantage

1)    The process is slightly more complex as compared to TIG.

2)    Welding equipment is more complex, more costly, and LESS portable.
3)    Since air drafts may disperse the shielding gas, Mig welding may not work well in outdoor welding applications.

 

MIG Welding Application

1)    The process can be used for the welding of carbon, silicon, and low alloy steel.

2)    For welding tool steel and dies.

3)    For the manufacture of refrigerator parts.
4)    Mig welding has been used successfully in industries like aircraft, automobiles, pressure vessels, etc.