With a neat sketch explain the principle and working of MIG welding. List its applications.

4. B]With a neat sketch explain the principle and working of MIG welding. List its applications.


MIG welding (Gas Metal Arc Welding):

  • Gas metal arc welding (GMAW) is the process in which arc is struck between bare wire electrode and work piece as shown in the figure. The arc is shielded by a shielding gas and if this is inert gas such as argon or helium then it is termed as metal inert gas (MIG) and if shielding gas is active gas such as CO2 or mixture of inert and active gases then process is termed as metal active gas (MAG) welding. Figure illustrates the process of GMA welding.
With a neat sketch explain the principle and working of MIG welding. List its applications.
Figure: Metal Inert Gas (MIG) welding
  • Direct current power source is the requirement of GMAW process. The electrode wire passing through the contact tube is to be connected to positive terminal of power source so that stable arc is achieved.
  • GMA welding requires consumables such as filler wire electrodes and shielding gas. Solid filler electrode wires are normally employed and are available in sizes 0.8, 1.0, 1.2- and 1.6-mm diameter. Similar to submerged arc welding electrode wires of mild steel and low alloyed steel, are coated with copper to avoid atmospheric corrosion, increase current carrying capacity and for smooth movement through contact tube
  • The process is extremely versatile over a wide range of thicknesses and all welding positions for both ferrous and nonferrous metals, provided suitable welding parameters and shielding gases are selected. High quality welds are produced without the problem of slag removal. The process can be easily mechanized / automated as continuous welding is possible.
  • However, process is costly and less portable than manual metal arc welding. GMA welding has high deposition rate and is indispensable for welding of ferrous and specially for nonferrous metals like aluminium and copper-based alloys in shipbuilding, chemical plants, automobile and electrical industries. It is also used for building structures.

Application of MIG welding :

  • Superb quality welded is produced within very less time.
  • Flux is not used in MIG process. So slag entrapment is there. High-quality weld is produced without any contamination.
  • The arc shields provide protection to the arc. So very less power is lost in the environment from the alloy. The weld spatter produced is also very less.
  • Different types of materials can be welded in MIG. It is a very versatile form of welding.
  • Semi and fully automatic processes are there. So it is very effective and easier to use.
  • The weld pool is easily visible. So it is very easy for the welder to perform the welding.
  • Very less post-welding cleaning required whether in normal arc welding it requires a lot of cleaning and treatment.
  • MIG welding provides higher rates of production. In MIG there is no need to change the electrode. There is no slug removing process needed. So welders can enjoy a faster and cleaner welding process. The productivity increases a great deal.
  • Actually, MIG welding is very easy to perform. Even a technician with basic welding idea can perform MIG. But TIG welding is much tougher than the MIG.
  • While performing the MIG welding, both or at least one hand remains free as the electrode is continuously fed by the feeding mechanism. So a faster welding with great quality is observed.
  • The deposition rate is higher in MIG welding.
  • The process is ultra-low hydrogen process.

Leave a Reply

Your email address will not be published. Required fields are marked *