Section 4: Basic Welding Guide; Mig (Gmaw/Fcaw) Basic Welding Technique - ESAB fabricator 141i Operating Manual

SECTION 4: BASIC WELDING
GUIDE
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 welding, Micro Wire Welding, short arc
2
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 continu-
ous, 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 oper-
ated 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 sup-
plied gas or gas mixture. The process is normally applied semi
automatically; however the process may be applied automati-
cally or by machine. It is commonly used to weld large diam-
eter 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.
Manual 0-5420
Position of MIG Gun
The angle of MIG Gun to the weld has an effect on the width of
the weld.
The welding Gun should be held at an angle to the weld joint.
Nozzle
(see Secondary Adjustment Variables below)
Electrode
Hold the MIG Gun so that the welding seam is viewed at all
Arc
times. Always wear the welding helmet with proper filter
lenses and use the proper safety equipment.
Base Metal
Art # A-8991_AB
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.
4-1
ESAB FABRICATOR 141i
Shielding Gas
(Optional)
Molten Metal
Molten
Slag
Slag
Solidified
Weld Metal
FCAW Process
Figure 4-2
Vertical
Push
Figure 4-3
CAUTION
!
Do NOT pull the welding MIG Gun back
when the arc is established. This will cre-
ate excessive wire extension (stick-out)
and make a very poor weld.
5° to 15°
Longitudinal
Angle
90°
Transverse
Angle
Butt & Horizontal Welds
Figure 4-4
Nozzle
(Optional)
Flux Cored
Electrode
Arc
Base Metal
Art # A-08992_AB
Drag/Pull
Art # A-07185_AB
Direction of
Travel
Art # A-08993
BASIC WELDING GUIDE