What is Gas Metal Arc Welding(MIG)?
Introduction
MIG stands for metal inert gas welding or sometimes it is known as Gas Metal Arc welding. This process is automated or semi-automated arc welding process in which inert gases are used as shielding gas and a consumable wire electrode is used.
Principle
MIG works on basic principle of heat generation due to electric arc. This heat is further used to melt consumable electrode and base plates metal which solidify together and makes a strong joint. The shielded gases are also supplied through nozzle which protect the weld zone from other reactive gases.
Equipment
Power Source
In this type of welding process, a DC power supply is used with reverse polarity. Reverse polarity means the electrode or in case of MIG welding electrode wire is connected positive terminal and work piece to negative terminal
Wire Feeder System
MIG welding needs continuous consumable electrode supply for welding two plates. This consumable electrode used in form of wire. This wire is continuously supplied by wire feed mechanism or system. It controls the speed of the wire and pushes the wire form welding torch to welding area.
Welding Torch
This torch is slightly different as used in TIG welding. In this torch there is a mechanism which hold the wire and supply it continuously with the help of wire feed
Shielding Gas
The primary function of shielding gases is to protect weld area from other reactive gases like oxygen etc. which can affect the strength of welding joint. These shielding gases are also form plasma which helps in welding.
Regulators
As the name implies, they are used to regulate the flow of inert gases from the cylinder. The inert gases are filled into cylinder at high pressure. These gases cannot be used at this pressure so a regulator is used between the gases supply which lower down the gases pressure according to welding requirements.
Working
Its working can be summarized as follow:
- First, a high voltage current is change into DC current supply with high current at low voltage. This current pass though welding electrode.
- A consumable wire is used as electrode. The electrode is connected to the positive terminal and work piece from negative terminal.
- A fine intense arc will generate between electrode and work piece due to power supply. This arc used to produce heat which melts the electrode and the base metal. Mostly electrode is made by the base metal for making uniform joint.
- This arc is well shielded by shielding gases. These gases protect the weld form other reactive gases which can damage the strength of welding joint.
- This electrode travels continuously on welding area for making proper weld joint. The angle of the direction of travel should be kept between 10-15 degree. For fillet joints the angle should be 45 degree.
Mig welder kam karama he