LEARNING TO WELD
MIG (Metal Inert Gas) welding is the process
of uniting metallic parts by heating and
allowing the metals to flow together through
the use of an electrical arc. The electrical arc
is created between a continuous consumable
wire electrode (the welding wire) and the
work piece. An inert shielding gas is used to
protect the weld puddle from contamination
and enhance the welding capabilities of the
electrical arc.
Whether you have welded before or not, it is
important that you become familiar with your
new welder, its controls, and the results
achieved at different settings. We strongly
recommend that you practice with your new
welder on scrap metal trying different heat
settings, base metal thicknesses, and weld-
ing positions for each type and size of wire
you will be using. By doing this you will gain
a feel for how changes in these welding
variables affect the weld.
Of course, if you have not welded before,
you will need to develop welding skills and
techniques as well.
The self-taught welder learns through a
process of trial and error. The best way to
teach yourself how to weld is with short
periods of practice at regular intervals. All
practice welds should be done on scrap
metal that can be discarded. Do not attempt
to make any repairs on valuable equipment
until you have satisfied yourself that your
practice welds are of good appearance and
free of slag or gas inclusions. What you fail
to learn through practice will be learned
through mistakes and re-welds later on.
HOLDING THE GUN
The best way to hold the welding gun is the
way that feels most comfortable to you.
While practicing to use your new welder,
experiment holding the gun in different
positions until you find the one that seems to
work best for you.
Position the Gun to the Work Piece
There are two angles of the gun nozzle in
relation to the work piece that must be con-
sidered when welding.
14
1. Angle A (Figure 7) can be varied, but in
most cases the optimum angle will be 60
degrees. The point at which the gun
handle is parallel to the work piece. If
angle A is increased, penetration will
increase. If angle A is decreased,
penetration will decrease also.
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Figure 7. Gun Position, Angle A
.
Angle B (Figure 8) can be varied for two
reasons: to improve the ability to see the
arc in relation to the weld puddle and to
direct the force of the arc.
45 ° I
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Figure 8. Gun Position, Angle B
The force of the welding arc follows a
straight line out of the end of the nozzle.
If angle B is changed, so will the direction of
arc force and the point at which penetration
will be concentrated.
Qn a butt weld joint, the only reason to vary
angle B from perpendicular (straight up) to
the work piece would be to improve visibility
of the weld puddle. In this case, angle B can
be varied anywhere from zero to 45 degrees
with 30 degrees working about the best.
On a fillet weld joint, the nozzle is generally
positioned in such a manner so as to split
the angle between the horizontal and vertical
members of the weld joint. In most cases, a
fillet weld will be 45 degrees.
Distance from the Work Piece
The end of the welding gun is designed with
the contact tip recessed from the end of the
nozzle and the nozzle electrically insulated
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