Unimig VIPER 182 Mk II, Operating Manual

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MIG (Metal Inert Gas) Welding
MIG (metal inert gas) welding also known as GMAW (gas metal arc welding) or MAG (metal active gas welding),
is a semi-automatic or automatic arc welding process in which a continuous and consumable wire electrode
and a shielding gas are fed through a welding gun. A constant voltage, direct current power source is most
commonly used with MIG welding.
There are four primary methods of metal transfer in MIG welding, called short circuit (also known as dip
transfer) globular transfer, spray transfer and pulsed-spray, each of which has distinct properties and
corresponding advantages and limitations. To perform MIG welding, the necessary equipment is a welding
gun, a wire feed unit, a welding power supply, an electrode wire, and a shielding gas supply. Short circuit
transfer is the most commonly used method whereby the wire electrode is fed continuously down the welding
torch through to and exiting the contact tip. The wire touches the workpiece and causes a short circuit the
wire heats up and begins to form a molten bead, the bead separates from the end of the wire and forms a
droplet that is transferred into the weld pool. This process is repeated about 100 times per second, making the
arc appear constant to the human eye.
Short Circuit Transfer
Short circuit transfer is the most commonly used method whereby the wire electrode is fed continuously down
the welding torch through to and exiting the contact tip. The wire touches the workpiece and causes a short
circuit the wire heats up and begins to form a molten bead, the bead separates from the end of the wire and
forms a droplet that is transferred into the weld pool. This process is repeated about 100 times per second,
making the arc appear constant to the human eye.
Short Circuit
Short Circuit
Wire Heating
Wire Heating
Magnetic field
pinches wire
Magnetic field
pinches wire
The wire approaches the work piece and
touches the work creating a short circuit
between the wire and the base metal,
because there is no space between the
wire and the base metal there is no arc and
current flows through the wire.
The pinch causes the forming droplet to
separate and fall towards the now creating
weld pool.
The wire cannot support all the current
flow, resistance builds up and the wire
becomes hot and weak and begins to melt.
An arc is created at the separation of the
droplet and the heat and force of the arc
flattens out the droplet into the weld pool.
The heat of the arc melts the end of the wire
slightly as it feeds towards the base metal.
The current flow creates a magnetic field
that begins to pinch the melting wire
forming it into droplet.
The wire feed speed overcomes the heat of
the arc and the wire again approaches the
work to short circuit and repeat the cycle.
MIG WELDING GUIDE
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