Instructions / Assembly

32
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GMAW
Magnum® Cool-Arc Water Cooler
All GMAW torches for semiautomatic welding provide a duty
cycle rating. The heat generated and transferred to the torch
handle needs to be considered. The duty cycle of the GMAW
torch selected relates to the shielding gas and the maximum
current that is specific to the welding application. Most
air-cooled torches are rated at a 60% duty cycle for a specific
current, and their operation is based upon the use of 100% CO
2
shielding. If argon based blends are indicated, then the torch
duty cycle should be reduced by 50%.
Most GMAW torches come in lengths of 10 - 25 ft. (3 – 8 m) and
the length selected should provide no compromise for delivery of
the shielding gas and the electrode to the arc.
FIGURE 29: GMAW Torch Cutaway
T
he selection of a water-cooled torch for GMAW has several
a
dvantages. They are rated 100% duty cycle for their given
capacity. They increase the life of the consumable components
of the torch by approximately 50%. Water–cooled torches have
operator appeal because they reduce the heat transferred to the
G
MAW torch handle. The downside of a water-cooled torch is
that they tend to require more maintenance. Additionally, the use
of a water-cooled torch requires the purchase of a water cooler,
see photo below. Implementation of a water-cooled GMAW
t
orch depends largely upon the size of the electrode used, the
a
mount of time a welder spends at the arc, and the projected
cost of welding torch consumables.
TABLE 2: Magnum
®
Air-Cooled Torch Ratings and
Diameter Ranges
Magnum Rating Diameter Range Duty
Gun (Amps) Inches (mm) Cycle
Magnum 200 200
0.025 - 0.045
60
(0.6 - 1.1)
Magnum 300
300
0.035 - 5/64
60
(0.9 - 2.0)
Magnum 400 400
0.035 - 5/64
60
(0.9 - 2.0)
Magnum 550 550
0.035 - 1/8
60
(0.9 - 3.2)
MAGNUM GUNS
FIGURE 30: Semiautomatic GMAW Welding System
Insulated
Conductor Tube
Electrode Conduit
Gas Diffuser
Travel
Shielding Gas
Contact Tip
Electrode
Molten Weld Metal
Work
Solidified
Weld Metal
Arc