CO2 welding :An introduction of Metal active gas

CO2 welding :An introduction of Metal active gas

CO2 welding 

CO2 (Carbon-dioxide) welding is nothing but a variation of the standard MIG welding process.


In this process, carbon dioxide is used as active gas, hence it is also known as a metal active gas process.

CO2 is basically a semi-automatic process, in which the arc length and electrode wire feeding into the arc are automatically controlled.

Difference between CO2 and Mig Process

Typically in the MIG process, argon, helium, or their mixtures are used to protect the molten weld pool, while in the CO2 welding process carbon dioxide is used as the shielding gas.
In this process, carbon dioxide is used as active gas, hence it is also known as a metal active gas(MAG) process.

Benefits of CO2 welding 

        Although argon and helium are used for MIG welding of most metals, providing reliable and robust welding, carbon dioxide has become widely popular for arc shielding in the welding of steels.
Some of the main reasons for its popularity are as follows:
  • CO2 overcomes the restriction of using short lengths of electrodes as in the Shielded metal arc welding (stick welding) process.
  • The CO2 process overcomes the inability of the submerged arc welding process to weld in several welding positions.
  • CO2 welding requires less skill than TIG or shield metal ARC welding.

Welding equipment for CO2 welding

Following is the list of equipment used in CO2 welding:

A constant potential DC power source and controls.

DCRP(electrode positive) current is used in CO 2 process as it always facilitates smooth metal transfer with stable arc and minimum spatter. The use of DCSP and AC current is unsuitable as this makes the arc erratic and unstable.

In the CO2 process, a welding generator or a constant voltage type transformer-rectifier is used for the power source. A constant voltage power source with a constant speed wire feeder provides a self-correcting arc length system.

Wire feeder

The wire feeder pulls the wire electrode from the spool and pushes it through the welding gun at the required speed.
 Along with this, a DC motor, speed-reducing gearbox, rule drive gas solenoid valve, and potentiometer are fitted to adjust the speed, which helps in providing a constant speed to the wire.

Welding gun

Welding guns are of two types Lightweight types which are air-cooled  with shielding gas
While the other heavy type is water-cooled, it is used for more than 400 amperes current or heavy-duty.

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  1. Why are there limitations to the use of radiography in the certification of welders in semi-automatic welding?


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