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mNERT-GAS
METAL-ARC
WELDING
(Nonconsumabne)
ALLCABLES
SHOULD BE
KEPT S HORT
ASPOSSIBLE
(Donotex-
ceed 12-f/2
feet[nlength)
GROUNDED
WORK P IECE
OR WORK T ABLE
TOELECTRODE
/
HOLDER
/
/
GROURB
CLAMP
K.F.ATT
WELDER
_/\
GROUND
CABLE I
GROUND
CABLE
_,,o
g
230VOLT
_=========E_6O
CYCLE
SINGLE PHASE
HiGHFREQUENCY
ATTACHMENT
WELDING CABLE T O WELDER
Figure I
ANY CRAFTSMAH
WELDER
MAY BEUSED WiTH HF,
ATTACHMENT
[]
D
O_
o
o
WELDER
CABINET
MUST BE
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 is usually 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 used for 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
is not 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 is assembled 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 is usually
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 is applied by hand feeding the filler rod
(from the side) into the pool of molten metal in the region
of the arc. Filler rod is added in essentially the same manner
when welding by the oxyacetylene
method.
1-19
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