47
Component Identification and Explanation
versed in MIG quickly develop 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 pene-
tration 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 deep-
er 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 ALWAYS push the gun. If
using Flux Cored wire, a dragging motion is almost always recommended.
For TIG, a push angle of the torch is always recommended. This keeps the
gas pushing in front of the weld, and keeps shielding built up in front of
the weld. The ller rod should be introduced in front of the torch travel.
For Stick, a drag angle should be used unless welding vertically. The angle
may change to a more perpendicular or push angle to keep the puddle in
place.
Weaving in Welding. Weaving (oscillating the torch or electrode from side
to side in one pattern or the other), particularly in MIG, 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 soundest welds for a beginner in MIG or Stick. Stringer welds
leave little or no room for contaminates to enter the weld and are the fast-
est to produce without creating an opportunity for cold lap. Moving too
quickly however with a stringer can create undercut 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 together. 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.
Vertical stick will use a more exaggerated side to side Z pattern weave
when traveling up hill on thicker plate metals. Whether it is MIG, TIG or
Stick, weave patterns are employed for a number of reasons. Weaves are
often considered to have a more pleasing appearance and can help bridge
gaps where t up is a problem. A weave is also frequently used to man-
age heat build up. For example: when welding vertically weaves are al-
most 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 prac-
ticed before employing it in any structural or critical application.
Metal Cleaning.
MIG and TIG 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. In TIG welding it can be
disastrous. TIG requires the most cleaning effort. A grinder will usually
prep the metal sufciently 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!
MIG and TIG ller wires such as ER70S-6 or ER70S-2 include a sufcient
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. MIG and TIG ER70S-2 and ER70S6 are the same except that TIG
wire is cut to lengths and MIG wire is continuous. When welding ne
gauge materials in TIG, you can substitute sections of thinner MIG wire.
Multiple Pass Welds.
One of the common misunderstandings that people have when beginning
to weld is that if the welder has the power, then a single heavy pass should
be used to weld it up. This is wrong. This technique will induce cold-lap
and inclusions to the weld. Single pass welds should not exceed 1/4” even
with the heaviest wire the welder is capable of handling. A thick pass may
also begin to cool before contaminates and gas pockets have the time to
float out to the surface. It’s far better to make multiple smaller passes to
complete a plate weld for a higher quality result. For best results, this
requires that most joints 1/4” and over be prepared with a grinder to ac-
cept multiple weld passes. The weldment edges should be ground to form
a V, U or J shaped groove to create a recess where the welds can be weld-
ed one on top of another. For MIG/Flux-Cored welding with .035” wire and
under, create a bead no thicker than 3/16” in a single pass, no more than
1/8” with .030” wire, and with .025”wire and smaller no more than 3/32 for
best results. This will help maintain proper fluidity of the weld and prevent
gas from being trapped in the weld and give time for any minor contami-
nates to float out of the weld. It will also help to maintain reasonable for-
ward travel speeds. Too slow of travel speeds will create excess build up
and can tend to create cold lap at the weld toes resulting in poor tie in.
One issue created with a weaving technique even if the metal deposited is
the correct thickness is that it can slow the forward progress down. If
weaving is too wide, one side of the puddle will cool and oxidize before
the torch is brought back across to that side. This is a point where porosity
Explanation of Parameters, Functions and Welding Terms
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