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mNERT-GAS METAL-ARC WELDING (Nonconsumabne)
ALLCABLES
SHOULDBE
KEPTSHORT
ASPOSSIBLE
(Donotex-
ceed12-f/2
feet[nlength)
GROUNDEDWORKPIECE
ORWORKTABLE
TOELECTRODE /
HOLDER /
/ GROURBCLAMP
K.F.ATT WELDER
_/\ GROUNDCABLE I GROUND
CABLE
_,,o g 230VOLT
_=========E_6OCYCLE
SINGLEPHASE
HiGHFREQUENCY
ATTACHMENT
WELDINGCABLETO WELDER
Figure I
ANYCRAFTSMAHWELDER
MAYBEUSEDWiTHHF,
ATTACHMENT
[] D
O_
o o WELDER
CABINET
MUSTBE
GROUNDER
ACORDOWELDER
Figure 2
HIGH FREQUENCY ATTACHMENT
The Craftsman, High-Frequency Attachment may be used
with any Craftsman welder or other single-phase, trans-
former_type welder of high quality construction having an
AC, or AC/DC power output Tungsten inert gas (T.LG.)
welding has many useful and advantageous applications
as described in the following paragraphs_ In order to use
the T.LG. process with an AC welder, a high-frequency
attachment must be provided_ Figure 1 shows a typical
hookup using this high-frequency attachment with a Crafts-
man welder_ When not using the TJ.G, welding process, the
high-frequency attachment also permits easy "arc" start.
ing and greatly improved results with many hard-to-weld
rods (low hydrogen rods) as well as making the welding
operation much easier to perform.
The use of a hlgh-frequency attachment makes possible the
establishment of an arc without touching the electrode to
the work., Once the arc has been established, it isstabilized
by the hlgh-frequency output_ This is essential in the T.I.G.
process in order to avoid contaminating the tungsten elec-
trode or the work..
PRINCIPLES OF OPERATION
The necessary heat for inert-gas welding (nonconsumable)
is produced by an electric arc maintained between the non-
consumable electrode and the work-piece. The electrode
used for carrying the current isusually a tungsten or tungsten
alloy rod_ The heated weld zone, the molten metal and the
nonconsumable electrode are shielded from the oxidizing
effects of the atmosphere by a blanket of inert gas fed
through the TJ_G. torch and the weld is made by applying
the arc heat until the abutting edges of the work-places are
melted, adding filler rod if necessary_ The resultant pool
of molten metal, upon solidifying, joins the edges of the
members togethen The process may also be usedfor adding
metal to surfaces, Iocally-meltlng and spot-joinlng parts.
A thorough cleaning of the surface to be welded isrequired_
Alloil, grease, paint, rust, dirt or other contaminants must
be removed either by mechanical means or by the use of
vapor or liquid cleaners, Files, chisels and stainless wire
brushes may be used Grinding isnot recommended, Liquid
cleaners such as naphtha, mineral spirits, alcohol, acetone
and methyl-ethyl-ketone can be used All surfaces must be
wiped dry with a clean cloth, Cleaners should not be used
after a joint isassembled prior to welding,
Striking the arc may be accomplished as follows:
1_ Touching the electrode to the work momentarily and
quickly withdrawing it a short dlstance_ (DC power source)
2 Use of an apparatus which will cause a spark to jump
without touching the electrode to the work. (AC power
source with high-frequency unit attachment)
The high-frequency arc stabilizer provides for this latter
method of starting the arc. Such devices are not required
with DC, consequently it is usually necessary to touch the
electrode to the work to start the arc.
For manual welding, once the arc is started, the electrode
holder is held with the electrode positioned at an angle of
about 75 degrees to the surface of the weld puddle as
shown in figure 2 To start the welding, the holder isusually
moved in a small circle until a pool of molten metal of suit-
able size is obtained. Once adequate fusion is achieved at
any one point, a weld is made by gradually moving the
electrode along the parts to be welded to melt the adjoin-
ing edges progressively, adding filler rod as required.
Solidification of the melted metal follows progression of
the arc along the joint and completes the welding cycle_
Material thickness, joint design and weld characteristics
desired will determine whether or not filler metal should
be added to the joints_ When filler metal is added during
manual welding, it isapplied by hand feeding the filler rod
(from the side) into the pool of molten metal in the region
of the arc. Filler rod isadded in essentially the same manner
when welding by the oxyacetylene method.
1-19
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