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What is MIG Welding?
MIG welding is an arc welding process that joins metals by heating them with
an arc. MIG and flux cored welders offer advantages over other welding processes for
both new and veteran welders. The welding machine creates an arc between the
metal and a consumable electrode, known as the mig welders wire.
The operator concentrates on directing the MIG welder gun at the joint and
proper motion. Most MIG welders can also flux cored weld.
Mig welders use aluminum alloy wire
Gas Metal Arc Welding (GMAW) is frequently referred to as MIG welding. It is a commonly used high deposition rate welding process. Wire is
continuously fed from a spool. MIG is a
semiautomatic welding process
Externally supplied gas or gas mixtures provide shielding for mig welders.
Common MIG welding is also referred to as short circuit transfer. Metal is
deposited only when the wire actually touches the work. No metal is transferred
across the arc.
Another method of MIG welding, spray transfer moves a stream of tiny molten
droplets across the arc from the electrode to the weld puddle. Consumables:
contact tips, shielding gas, welding wire.
Mig welders use direct current power source, with the electrode positive.
The metal is transferred from the filler wire to the weld bead by magnetic
forces as small droplets called spray transfer. This gives the mig welder deep
penetration and makes it easy to weld in all positions. It is important for the
quality of the weld that the spray transfer is obtained.
There are two different MIG welding processes, conventional MIG welders and
pulsed MIG welders
MIG welders use a constant voltage DC power source. Since the spray
transfer is limited to a certain range of arc current, the conventional MIG
welder process has a lower limit of arc current. This also limits the
application of conventional MIG to weld material thicknesses above 4 mm.
Pulsed MIG welders use a DC power source with superimposed periodic pulses
of high current. Pulsed MIG welding is possible to operate with lower average
current and heat input compared to conventional MIG welders. This makes it
possible to mig weld thinner sections and weld much easily in difficult welding
Recommended material thicknesses for MIG-welding aluminum
Conventional MIG-welding: with or without backing: > 3 mm
Pulsed MIG-welding: > 1 mm. Smaller thicknesses are possible, however with
thinner diameter on welding wire.
For MIG welding of thick plates preheating of 50ñ100ƒC may be required to
avoid lack of fusion.