Mig/Mag Welding Process; Introduction To Metal Inert Gas (Mig) & Metal Active Gas (Mag) - Linde BOC RAPTOR 160 MIG Operating Manual

6.0 MIG/MAG Welding Process

Typical MIG/MAG set up
Torch trigger
Welding wire
Weld
Weld pool
6.1 Introduction to Metal Inert Gas (MIG)
& Metal Active Gas (MAG)
MIG/MAG welding embraces a group of arc welding
processes in which a continuous electrode (the
wire) is fed by powered feed rolls (wire feeder)
into the weld pool. An electric arc is created
between the tip of the wire and the weld pool. The
wire is progressively melted at the same speed at
which it is being fed and forms part of the weld
pool. Both the arc and the weld pool are protected
from atmospheric contamination by a shield of
inert (non-reactive) gas, which is delivered through
a nozzle that is concentric with the welding wire
guide tube.
Operation
MIG/MAG welding is usually carried out with a
handheld torch as a semi-automatic process. The
MIG/MAG process can be suited to a variety of job
requirements by choosing the correct shielding
gas, electrode (wire) size and welding parameters.
Welding parameters include the voltage, travel
speed, arc (stick-out) length and wire feed rate.
The arc voltage and wire feed rate will determine
the filler metal transfer method.
Extended self shielded flux cored wire nozzle
Torch
Shroud
Gas diffuser
Contact tip
Shielding
Droplets
This application combines the advantages of
continuity, speed, comparative freedom from
distortion and the reliability of automatic welding
with the versatility and control of manual welding.
The process is also suitable for mechanised set-
ups, and its use in this respect is increasing.
MIG/MAG welding can be carried out using solid
wire, flux cored, or a copper-coated solid wire
electrode. The shielding gas or gas mixture may
consist of the following:
Argon (MIG)
•
Carbon dioxide (MAG)
•
Argon and carbon dioxide mixtures (MAG)
•
Argon with oxygen mixtures (MAG)
•
Argon with helium mixtures (MIG)
•
Each gas or gas mixture has specific advantages
and limitations. Other forms of MIG/MAG welding
include using a flux-cored continuous electrode
and carbon dioxide shielding gas, or using self-
shielding flux-cored wire, requiring no shielding.
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