Metal Inert Gas Welding is abbreviated from MIG welding which has developed way back in 1940. This is categorized as a semi-automatic process where welder needs some technical skill. The welding machine does continuously keep supplying the electrodes or wire at the joint being welded. The electrodes need not be changed between the welding processes. Mig welding is an awesome process where electricity is used to melt and consequently join the metal together. This technique is sometimes called The Hot Glue Gun in the welding word and regarded as one of the easiest types of welding process to master. Nowadays this process of welding is visible in every industries and manufacturing process due to its high speed, automated qualities, high speed, and easy operation. It is mostly used in automobile industries and sheet metal industries.
Principle of Mig welding:
The heat generated by electric arc lead on to melting of the consumable electrode and base metal which solidify together to make a stronger joint. There is a supply of shielded gas to the weld one through the nozzle which protects the zone from reactive gases. To gives a good surface finish and a joint which is very strong.
Equipment of MIG Welding:
They are the followings.
Power Source – In the MIG welding process DC power supply is required with the reverse polarity. In the reverse polarity, the electrode wire is connected with a positive terminal and the negative terminal with the workpiece. Due to electric circuit principle, the 70% heat is there on the positive side which leads on to melting of the filler wire in a proper way. The power source includes a power supply, a rectifier, a transformer, which changes AC into DC current and some electronic control gadget to control the current supply as per welding requirement.
Wire Feeder –
The Mig welding process needs a continuous supply of wire electrode for welding of two workpiece together. The wire here is supplied as continuous process by the wire feeder. The wire feeder can control the speed of the wire and also pushes the wire from the torch to the welding area. This is available in the market with different shape and sizes. The wire feeder has wire spool holder, drive roll, motor to drive, and wire feed controls. The speed of the wire feed directly controls the current supply through the power source. The more current in the welding zone is required if wire feeding speed is high to produce the proper heat for the melting of the wire.
The mechanism in Mig torch holds the wire and supply continuously through the wire feeder. The torch is fitted with a nozzle at the front end which is used to supply the inert gases. These gases form a safe shielding area around the weld zone to protect from the oxidation. The torch may air cooled or water cooled as per the requirements. The low supply current needs air-cooled while higher supplied current needs water-cooled torches.
Shielding Gases – ,/h2>The weld area need protection from reactive gases like oxygen with the help of shielding gases. The oxidation may lead to badly affect the strength of the weld zone. These gases form plasma to help in welding. The gases may include mostly argon, helium, and other inert gases depending upon the material to be welded.
The flow of inert gases from the cylinder is regulated by the regulators. The inert gases are filled at high pressure in the cylinder. These gases cannot be used at such a high pressure so the regulators are mandatory to regulate the pressure as per the requirement at the welding zone.
Working Steps Mig Welding:
- A high voltage current needs to change to DC current at a low voltage which passes through the welding wire/electrode.
- The electrode here is Mig wire which is connected to negative terminal and workpiece needs to connect with the positive terminal.
- The power supply initiates a strong, fine, intense, arc between electrode and workpiece. The heat is produced with this arc which melts away the electrodes and base metal to produce a uniform weld zone.
- The shielding gases protect the arc from oxidation with reactive gases like oxygen to damage the welding zone.
- The wire travels continuously on the welding area at an angle of 10-15 degree to make proper weld joint.
Advantages of Mig Welding;
- Faster process of welding as a continuous supply of electrode.
- The higher deposition rate is the nature of Mig welding.
- The clean welding with better quality.
- The very little or no slag formation with the Mig welding.
- Automation can be added very easily with Mig welding.
- It can make deep groove welding.
Disadvantages of Mig Welding;
- It cannot weld by Mig in difficult to reach places.
- It may not be easy to set up outdoor Mig welding because of wind affecting shielding gases.
- The initial investment is a little high.
- The need for a trained welder is there for Mig welding.