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A Tig Book Inside

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The main disadvantage of the GTAW process is the low filler
metal deposition rate. Another disadvantage is that the
hand-eye coordination necessary to accomplish the weld is
difficult to learn, and requires a great deal of practice to
become proficient. The arc rays produced by the process
tend to be brighter than those produced by SMAW and
GMAW. This is primarily due to the absence of visible fumes
and smoke. The increased amounts of ultraviolet rays from
the arc also cause the formation of ozone and nitrous oxides.
Care should be taken to protect skin with the proper clothing
and protect eyes with the correct shade lens in the welding
hood. When welding in confined areas, concentrations of
shielding gas may build up and displace oxygen. Make sure
that these areas are ventilated properly.

No Sparks or Spatter
In the GTAW process there is no transfer of metal across the
arc. There are no molten globules of spatter to contend with
and no sparks produced if the material being welded is free
of contaminants. Also under normal conditions the GTAW arc
is quiet without the usual cracks, pops, and buzzing of
Shielded Metal Arc Welding (SMAW or Stick) and Gas Metal
Arc Welding (GMAW or MIG). Generally, the only time noise
will be a factor is when a pulsed arc, or AC welding mode is
being used.

No Smoke or Fumes
The process itself does not produce smoke or injurious
fumes. If the base metal contains coatings or elements such as
lead, zinc, nickel or copper that produce fumes, these must
be contended with as in any fusion welding process on these
materials. If the base metal contains oil, grease, paint or other
contaminants, smoke and fumes will definitely be produced
as the heat of the arc burns them away. The base material
should be cleaned to make the conditions most desirable.

Process Summary
GTAW is a clean process. It is desirable from an operator
point of view because of the reasons outlined. The welder
must maintain good welding conditions by properly cleaning
material, using clean filler metal and clean welding gloves,
and by keeping oil, dirt and other contaminants away from
the weld area. Cleanliness cannot be overemphasized,
particularly on aluminum and magnesium. These metals are
more susceptible to contaminants than are ferrous metals.
Porosity in aluminum welds has been shown to be caused by
hydrogen. Consequently, it is most important to eliminate all
sources of hydrogen contamination such as moisture and
hydrocarbons in the form of oils and paint...
II. GTAW Fundamentals
If you’ve ever had the experience of hooking up a car battery
backwards, you were no doubt surprised at the amount of
sparks and heat that can be generated by a 12 volt battery. In
actual fact, a GTAW torch could be hooked directly to a battery
and be used for welding.
When welding was first discovered in the early 1880s it was
done with batteries. (Some batteries used in early welding
experiments reached room size proportions.) The first
welding machine, seen in Figure 2.1, was developed by
N. Benardos and S. Olszewski of Great Britain and was issued
a British patent in 1885. It used a carbon electrode and was
powered by batteries, which were in turn charged with a
dynamo, a machine that produces electric current by
mechanical means.
Figure 2.1 Original carbon electrode welding apparatus 1885.
No Slag
There is no requirement for flux with this process; therefore,
there is no slag to obscure the welder’s vision of the molten
weld pool. The finished weld will not have slag to remove
between passes. Entrapment of slag in multiple pass welds is
seldom seen. On occasion with materials like Inconel
®
this
may present a concern.
No Sparks or Spatter
In the GTAW process there is no transfer of metal across the
arc. There are no molten globules of spatter to contend with
and no sparks produced if the material being welded is free
of contaminants. Also under normal conditions the GTAW arc
is quiet without the usual cracks, pops, and buzzing of
Shielded Metal Arc Welding (SMAW or Stick) and Gas Metal
Arc Welding (GMAW or MIG). Generally, the only time noise
will be a factor is when a pulsed arc, or AC welding mode is
being used.
No Smoke or Fumes
The process itself does not produce smoke or injurious
fumes. If the base metal contains coatings or elements such as
lead, zinc, nickel or copper that produce fumes, these must
be contended with as in any fusion welding process on these
materials. If the base metal contains oil, grease, paint or other
contaminants, smoke and fumes will definitely be produced
as the heat of the arc burns them away. The base material
should be cleaned to make the conditions most desirable.
GTAW Disadvantages
The main disadvantage of the GTAW process is the low filler
metal deposition rate. Another disadvantage is that the
hand-eye coordination necessary to accomplish the weld is
difficult to learn, and requires a great deal of practice to
become proficient. The arc rays produced by the process
tend to be brighter than those produced by SMAW and
GMAW. This is primarily due to the absence of visible fumes
and smoke. The increased amounts of ultraviolet rays from
the arc also cause the formation of ozone and nitrous oxides.
Care should be taken to protect skin with the proper clothing
and protect eyes with the correct shade lens in the welding
hood. When welding in confined areas, concentrations of
shielding gas may build up and displace oxygen. Make sure
that these areas are ventilated properly.
Process Summary
GTAW is a clean process. It is desirable from an operator
point of view because of the reasons outlined. The welder
must maintain good welding conditions by properly cleaning
material, using clean filler metal and clean welding gloves,
and by keeping oil, dirt and other contaminants away from
the weld area. Cleanliness cannot be overemphasized,
particularly on aluminum and magnesium. These metals are
more susceptible to contaminants than are ferrous metals.
Porosity in aluminum welds has been shown to be caused by
hydrogen. Consequently, it is most important to eliminate all
sources of hydrogen contamination such as moisture and
hydrocarbons in the form of oils and paint.
5
for GTAW
Gas Tungsten Arc Welding
TIGTIG
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