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 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 doesn’t 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