Full Product Manual

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weld as already mentioned. The gun should have no more
than 15 degrees lean pointed into (push) or pointed away
from (pull) the direction of travel. In most cases a push
motion is desired. However, a lot of texts offer conflicting
information on whether to push or to pull the gun. In reality,
both are correct if used correctly and with each having par-
ticular strength and weakness. Either one done with too
much gun angle will result in undesirable results. Most mod-
ern trained people who are well versed in MIG quickly de-
velop a sense of when to push and when to pull the gun.
Even for novices, a sense of when to push and pull the gun
comes quickly with a little practice. Pushing can result in
shallower penetration but the molten puddle is easier to see
and the arc sits easily on the leading edge. It will usually
leave a aesthetically pleasing bead. However, be careful to
prevent the gun from leaning toward or away from the direc-
tion of travel too much as spatter will increase and shielding
gas flow may become turbulent, creating porosity in the
weld. Pulling will result in deeper penetration, but can result
in a narrow bead without much side fusion. It also can leave
an undesirable humped appearance if not done correctly or if
travel is too slow. Whenever MIG welding with Aluminum,
whether with the standard MIG gun or the Spool gun AL-
WAYS push the gun. If using Flux Core, a dragging motion
is almost always recommended.
Weaving (oscillating the torch from side to side in one pat-
tern or the other), particularly a MIG bead, is a topic of con-
troversy as much as whether to push or pull the MIG gun.
Stringer beads are often best for novice welders. Stringers
are simply straight beads that move forward with little or no
side to side travel or oscillation. These will offer the sound-
est welds for a beginner. Stringer welds leave little or no
room for contaminates to enter the weld and are the fastest
to produce without creating an opportunity for cold lap.
Moving too quickly however with a stringer can create un-
dercut which will weaken the weld. The best policy is to
move a slow steady speed, making sure the sides of the weld
are lled. If undercut is present, it is either from too much
voltage or moving before the wire has time to ll the area the
arc has melted.
Think of weaving as a method of “sewing” the metal togeth-
er. If weaving is of interest to you, start with the basic weave
pattern. Simple weaves using one variation or the other of a
cursive “e” motion are best to begin with. Other weave
patterns can be used of course. C’s, V’S, U’s , Triangles and
many more weave patterns can be used depending upon the
application. Weaves are employed for a number of reasons.
Weaves are often considered to have a more pleasing ap-
pearance and can help bridge gaps where t up is a prob-
lem. A weave is also frequently used to manage heat build
up. For example: when welding vertically weaves are almost
always used to prevent the molten metal from sagging due to
the force of gravity. The major drawback of weaving is that it
introduces a greater possibility of getting inclusions and
other forms of contamination in the weld. Properly done
weaving is a valuable tool, but it must be practiced before
employing it in any structural or critical application.
Metal Cleaning.
MIG welding requires a well prepped surface to obtain a
sound weld. The removal of paint, rust mill scale, or other
contaminate such as grease should be done before welding.
Stick welding is more forgiving of rust and mill scale, but
when MIG welding, contaminates will result in porosity and
inclusions in the weld, weakening it. A grinder will usually
prep the metal sufciently to remove oxidation and paint.
However, to remove grease a degreaser such as acetone
should be used. Do not use any degreaser such a brake
cleaner with chlorinated solvents or death or serious injury
may occur!
A MIG wire such as ER70S-6 or ER70S-2 includes a suf-
cient level of deoxidizers such as silicone and copper that
are formulated to allow it to handle minor to moderate
amounts of rust and mill scale. These deoxidizers will float
out most moderate amounts of contaminates out of the weld
and will appear in the usual form of glassy like deposits on
top of the cooled metal. They are easily brushed off before
starting the next pass. They should not be welded over.
Any pinholes that appear are a result of trapped gas in the
weld and should be ground out before the next pass. It
should be noted that some MIG wires such as ER70S-3 have
low levels of deoxidizers and must be thoroughly cleaned
and ground before welding.
Multiple Pass Welds.
One of the common misunderstandings that people have
when beginning to MIG weld is about weld capability. Many
mistakenly believe that if the welder has the amperage output
to weld something in a single pass, then it is ne to weld it
that way. In fact marketing often drives this kind of thought
in comparisons and minimum/maximum statements. How-
ever, this is a primary way to introduce cold lap and incom-
plete fusion to the weld. As a best practice, single pass
1/4”-3/8”
(6mm– 9mm)
MIG OPERATION AND THEORY
Section 3 Basic Theory and Function