Section 4: Basic Welding Guide; Mig (Gmaw/Fcaw) Basic Welding Technique - Firepower MST 180i Operating Manual

4.01 MIG (GMAW/FCAW) Basic Welding
Technique
Two different welding processes are covered in this section
(GMAW and FCAW), with the intention of providing the very
basic concepts in using the MIG mode of welding, where a
welding MIG Gun is hand held, and the electrode (welding
wire) is fed into a weld puddle, and the arc is shielded by
an inert welding grade shielding gas or inert welding grade
shielding gas mixture.
GAS METAL ARC WELDING (GMAW): This process, also
known as MIG welding, CO
short arc welding, dip transfer welding, wire welding etc., is
an electric arc welding process which fuses together the parts
to be welded by heating them with an arc between a solid
continuous, consumable electrode and the work. Shielding is
obtained from an externally supplied welding grade shielding
gas or welding grade shielding gas mixture. The process is
normally applied semi automatically; however the process
may be operated automatically and can be machine operated.
The process can be used to weld thin and fairly thick steels,
and some non-ferrous metals in all positions.
Shielding Gas
Molten Weld Metal
Solidified
Weld Metal
GMAW Process
Figure 4-1
FLUX CORED ARC WELDING (FCAW): This is an electric arc
welding process which fuses together the parts to be welded
by heating them with an arc between a continuous flux filled
electrode wire and the work. Shielding is obtained through
decomposition of the flux within the tubular wire. Additional
shielding may or may not be obtained from an externally
supplied gas or gas mixture. The process is normally applied
semi automatically; however the process may be applied
automatically or by machine. It is commonly used to weld
large diameter electrodes in the flat and horizontal position
and small electrode diameters in all positions. The process
is used to a lesser degree for welding stainless steel and for
overlay work.
Shielding Gas
(Optional)
Molten Metal
Molten
Slag
Slag
Solidified
Weld Metal
FCAW Process
Figure 4-2
Manual 0-5339

SECTION 4: BASIC WELDING GUIDE

welding, Micro Wire Welding,
2
Nozzle
Electrode
Arc
Base Metal
Art # A-8991_AB
Nozzle
(Optional)
Flux Cored
Electrode
Arc
Base Metal
Art # A-08992_AB
Position of MIG Gun
The angle of MIG Gun to the weld has an effect on the width
of the weld.
Push
The welding Gun should be held at an angle to the weld joint.
(See Secondary Adjustment Variables below)
Hold the MIG Gun so that the welding seam is viewed at all
times. Always wear the welding helmet with proper filter
lenses and use the proper safety equipment.
Do not pull the welding MIG Gun back when the
arc is established. This will create excessive wire
extension (stick-out) and make a very poor weld.
The electrode wire is not energized until the MIG Gun trigger
switch is depressed. The wire may therefore be placed on
the seam or joint prior to lowering the helmet.
5° to 15°
Longitudinal
Transverse
Butt & Horizontal Welds
Longitudinal Angle
Horizontal Fillet Weld
4-1
Firepower MST 180i
Vertical
Figure 4-3
CAUTION
Angle
90°
Angle
Art # A-08993
Figure 4-4
5° to 15°
Transverse Angle
Direction of
Travel
Art # A-08994
Figure 4-5
Drag/Pull
Art # A-07185_AB
Direction of
Travel
30° to 60°
BASIC WELDING GUIDE