MIG/ MAG welding is a method of welding metal arcs in a protective gas environment, also known as welding wires, CO2 welding. Gas Metal ARC Welding (GMAW) is another name of MIG/MIG welding
MIG (Metal inert gas): Inert gas used in welding alloy steel and nonferrous metals.
MAG (Metal active gas): gas activated when welding ordinary steel, low alloy steel.
Inert gas: Mainly Argon or Hélium (blended gas).
Activation: Often (CO2), or Argon is added with oxygen (O2), sometimes with hydrogen (H2).
MIG-MAG welding uses an arc formed between the molten electrode wire and automatically supplied to the welding element. This arc is protected by inert gas or reducing gas. The fire of the arc is maintained by adjusting the electrical properties of the arc. The arc length and welding current strength are maintained automatically while the welding speed and electrode angle are maintained by the welders.
Advantages of MIG-MAG welding method
- High productivity
- Low cost - Low welding power, less thermal deformation.
- Able to weld most metals.
- Easy automation.
- Long welds can be made without interruption.
- Require low welding skills.
Metal transfer during MIG-MAG welding
Short Circuit Arc Transfer (Short Arc)
Average intensity: 50 to 150 A.
Detail thickness: 0.5 to 2 mm.
In this type of translation, welding power has the lowest value, due to its low welding currents and arc voltages. The shift occurs because of the continuous short-circuits between the electrode and the puddle. The volt-amps nature of the welding power play an important role in this type of shifting. Because of the low welding power, shallow depth of field needs special attention when welding thick parts. This feature of short-circuit switching makes reverse welds easier, especially for thin metal applications.
In short, short shifts are suitable for the following applications:
- Apply when soldering class.
- Apply when welding on thin sheet.
It is made sure that:
- The contact tube tip is protruding from the spray nozzle from 5 to 10 mm during welding
Electrodes (ESO) 5 mm.
- Angle of the torch from 65 ° to 70 °.
Average welding currents: 150 to 300 A.
Detail thickness: 2 to 6 mm.
In this type of shifting, the metal shifts from electrode to welding puddle in the form of spherical droplets of irregular size and random orientation, resulting in increased splash. When welding with CO 2, the splice can be reduced by adjusting the welding parameters so that the welded wire dips into the flowing hole and the burnt arc in the hole in the flowing hole. CO2 arcs are often unstable and when soldered they sound like broken branches. The characteristic of this arc is that it is more boring than other shifts. Because the arc is immersed in the puddles, the welding line has a very deep penetration, which effectively cleans up the poorer arc.
Bridge translation is applied in the following cases:
- Welding coating.
- Workpiece thickness is large
- Welding in a flat posture.
Spray Arc Welding
Average welding current intensity> 300 A.
Detail thickness> 6 mm.
This occurs when the protective gas has more than 80% argon. In this type of shifting the metal droplets are equal in size or smaller than the wire diameter. The droplets of metal are oriented along the arc axis. The fire is smooth and stable, resulting in less splashing and more flat weld. Arc energy (Plasma) spread across the conical region to make the edge of the weld be clean, but it also causes defects due to lack of flow for the weld edge. The penetration depth of this type of deformation is deeper than that of welding with the same grade but lower than that of a higher welding energy.
Application in coating or finishing
- welded on thick sheets
- Used in welding flat.
In order to ensure the spray displacement needed:
- The contact tube should be in the nozzle.
ESO papillary fever is about 20 mm.
- Angle of trench 75 ° to 85 °.
Video describing the types of shifting in MIG welding:
Currently, there are 03 types of technology for TIG welding machines: Diote, Thyristor and Inverter. Depending on the requirements and the level of investment, MIG diote (cheap - easy to fix) or MIG Thyistor welding machine or MIG Inverter welding machine can be used.