Instructions / Assembly

31
GMAW
www.lincolnelectric.com
GMAW Torches
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Torch Nozzle Water-Cooled Torch
Contact Tip Air-Cooled Torch
Torch Barrel Water Cooler
Gas Diffuser Torch Duty Cycle
Torch Liner
The selection of the proper GMAW torch, commonly
called a MIG gun, depends upon the following
factors:
•
Type of welding: semiautomatic, hard automation
or robotic automation.
• Level of current (amps) required by the welding
application and capacity of the torch.
• Shielding gas selected.
•
Duty cycle of the torch.
•
Preference of an air-cooled or water-cooled torch.
Semiautomatic GMAW Welding
The GMAW torch provides a conduit for the welding current, the
shielding gas, and the electrode. The welding current is picked up
at the torch power block located on the wire drive. Current
transfers from the welding cable to the electrode through the
contact tip. Contact tips are available in a range of sizes
designed to accommodate the electrode diameter in use, and
they usually attach to the gas diffuser via a threaded connection.
FIGURE
28: GMAW Torch Cutaway
F
IGURE 27: Portable Engine Driven GMAW System
The electrode is fed through an internal liner usually located
internal to the power cable. The shielding gas connections are
located at the welding gun mounting block on the wire drive.
They connect to the output side of the gas solenoid. The gas
flows to the gas diffuser, which uniformly delivers the gas to the
arc. The nozzle size is selected depending on the electrode
diameter and the shielding gas rate of flow.
Most of the welding with the GMAW process requires a
selection of a torch that will meet the anticipated comfort level
of the welder and simultaneously meet the wear requirement
imposed by the welding operation. The welding current used in
the application is primary to the selection, and the durability of
the torch under conditions of the arc dictates the appropriate
GMAW torch size.
Ranger 305D
Power Supply
LN-25 Wire Feeder
Gas Cylinder with
Flow Meter
Workpiece
Welding Torch
Gun Housing
Hanger
Nozzle
Gas Diffuser
Contact Tip
Trigger
Trigger
Leads
Cable to
Conductor Tube
Connection
Braided Copper
Power Cable
Power Cable
Insulation
Conductor
Tube