Guidelines For Gas Metal Arc Welding (GMAW)

Gas Metal Arc Welding (GMAW) is a welding process which joins metals by heating the metals to their melting point with an electric arc. The arc is between a continuous, consumable electrode wire and the metal being welded. The arc is shielded from contaminants in the atmosphere by a shielding gas.
GMAW can be done in three different ways:
Semiautomatic Welding - equipment controls only the electrode wire feeding. Movement of welding gun is controlled by hand. This may be called hand-held welding.
Machine Welding - uses a gun that is connected to a manipulator of some kind (not hand-held). An operator has to constantly set and adjust controls that move the manipulator.
Automatic Welding - uses equipment which welds without the constant adjusting of controls by a welder or operator. On some equipment, automatic sensing devices control the correct gun alignment in a weld joint. Basic equipment for a typical GMAW semiautomatic setup: Welding Power Source - provides welding power. Wire Feeders (Constant Speed And Voltage-Sensing) - controls supply of wire to welding gun. Constant Speed Feeder - Used only with a constant voltage (CV) power source. This type of feeder has a control cable that will connect to the power source. The control cable supplies power to the feeder and allows the capability of remote voltage control with certain power source/feeder combinations. The wire feed speed (WFS) is set on the feeder and will always be constant for a given preset value. Voltage-Sensing Feeder - Can be used with either a constant voltage (CV) or constant current (CC) - direct current (DC) power source. This type of feeder is powered off of the arc voltage and does not have a control cord. When set to (CV), the feeder is similar to a constant speed feeder. When set to (CC), the wire feed speed depends on the voltage present. The feeder changes the wire feed speed as the voltage changes. A voltage sensing feeder does not have the capability of remote voltage control. Supply of Electrode Wire. Welding Gun - delivers electrode wire and shielding gas to the weld puddle. Shielding Gas Cylinder - provides a supply of shielding gas to the arc.

1 Constant Voltage (CV)
Welding Power Source
2 Contactor Control/Power Cord
3 Weld Cable To Feeder
4 Ground Cable To Workpiece
5 Workpiece
6 Welding Gun
7 Constant Speed Wire Feeder
8 Electrode Wire
9 Gas Hose
10 Shielding Gas Cylinder