Longevity ARCMATE 205 - Manual (Page 26)

160/205 MIG Welder/ARC Welder
Page 25 of 37
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Welding gun and wire feed unit
GMAW torch nozzle cutaway image: (1) Torch handle (2) Molded phenolic dielectric (shown in white)
and threaded metal nut insert (yellow) (3) Shielding gas diffuser (4) Contact tip (5) Nozzle output face
A GMAW wire feed unit
The typical GMAW welding gun has a number of key parts—a control switch, a contact tip, a
power cable, a gas nozzle, an electrode conduit and liner, and a gas hose. The control switch, or
trigger, when pressed by the operator, initiates the wire feed, electric power, and the shielding
gas flow, causing an electric arc to be struck. The contact tip, normally made of copper and
sometimes chemically treated to reduce spatter, is connected to the welding power source
through the power cable and transmits the electrical energy to the electrode while directing it to
the weld area. It must be firmly secured and properly sized, since it must allow the passage of the
electrode while maintaining an electrical contact. Before arriving at the contact tip, the wire is
protected and guided by the electrode conduit and liner, which help prevent buckling and
maintain an uninterrupted wire feed. The gas nozzle is used to evenly direct the shielding gas
into the welding zone—if the flow is inconsistent, it may not provide adequate protection of the
weld area. Larger nozzles provide greater shielding gas flow, which is useful for high current
welding operations, in which the size of the molten weld pool is increased. The gas is supplied to
the nozzle through a gas hose, which is connected to the tanks of shielding gas. Sometimes, a
water hose is also built into the welding gun, cooling the gun in high heat operations.