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of the fractured surface to line up the two pieces. Tack-weld
or cramp parts in position. If the crack has not separated
the casting, a vee-groove can be chipped out with a dla-
mond_point chisel. Chip an inch or so beyond
the visible
ends of the crack as it may extend under the surface. On
cracked water jackets, where only a seal is required,
the
depth of the groove need only be one-half the thickness
of the casting.
Keep the casting as cool as possible and do not expect to
compiete a weld in cast iron as rapidly as in the same Length
in mild steel. Use a smaWer rod and a slightly higher current
than for the same thickness of steel. Lay a short bead, about
an inch tong, at one end of the crack and peen it immediately
with a cross-peen hammer
or blunt chisel to spread the
weld metal and relieve locked-up stresses. Do not strike the
edges of the casting. Place the second bead at the opposite
end of the crack and the next in the center, etc (fig. I).
Allow enough lime between welding
to permit your bare
hand to be held on it. Never use water or a blast of air
to cool the casting.
Although
cracks may not show up
immediately,
the tacked-up stresses due to uneven cooling
will cause the casting to fail after it is back in service. Wire
brush each bead before depositing the next. Then continue
to fil! the groove with short weld beads as before, working
rapidly when depositing and peening the bead. Albw plenty
of time for co01ing. Examine the casting for cracks that may
develop during cooling periods. If any of the beads crack,
chip them out and re-wetd,
tf c_acking persists, preheat
the entire casting slowly to a dull red heat with ar_ oxyacety-
lene torch or blow-torch.
When the preheated
method is
used, the welding can be continuous. After completing the
weld, cover the casting with warm dry sand or slaked lime
so it will coof slowly.
Malleable iron is ordinary gray cast iron that has been heat
treated to give it a tough ductile outer skin. The method of
welding is the same as for cast iron.
FIRST BEAD
THIRD HEAO
SECBH_ READ
FACING
WORN
CUTTING
EDGES
HARD FACING
OR UHOERSI_E
Figure
t
Excavating
equipment,
earth-cutting
farm
machinery
or
others
such as plow
shares,
lister shares, cultivator
shovels,
sweeps,
subsoilers,
spike
harrow
teeth,
tractor
treads,
ex-
cavating
buckets,
or any surface
subject to abrasive
action
will
last
much
longer
and
require
less sharpening
when
their
cutting
edges
are
hard
faced
with
hard
surfaclng
electrodes.
The arc welding
process
consists
of depositing
a fayer of abrasion
resisting
weld
metal on the worn
cuffing
edges as indicated
in red on the parts shown
in figure
1.
Prepare the part for welding by cleaning the surface to be
welded
by grinding
it approximately
1-1/2
inches back
from the edge (fig. 2). Position the part so weld metal can
be deposffed in the flat position. If the material
is 1!4-inch
thick or less, use a Ii8-inch
rod and as low a current as
possible that will still permit the metal to flow out smooth
and fairly thin (t/t6
to 1/8-inch
thick). Weave the rod
from side-to-side
in a crescent-shaped movement and de_
posit a bead about 3/4
to 1-inch wide. Severat passes
(lald side-by-side)
may be necessary where the worn sur-
faces are quite wide. In some cases a small straight bead
___
........................
i
_, iiiiiiiii
GRIND OFF
WEAVE BEADS
,1"'_
1-1/2 IHCH "_
_MAt.L
BEAt]..,.J
F_gure
2
F_gure
3
HARD FACING
HARO FACIH_
--
/-
F;gure
4
_
_EEL
SOFT BASE METAL
.,L!D-S'tEEL
PATC,
WEARSAWAY FASTER
WELDS
THAH HARD FACIN_
Figure
5
_111,,i,,,
i
1,1!
ii
must be deposited along the edge to buiJd it up (fig. 3).
Make beads heaviest where the wear will be greatest, but
avoid excessive build-up
as the metal cannot be flied or
machined, if shaping is required,
heat the wetd metal and
forge it. Smoothing
and sharpening
can be accomplished
by grinding.
For plow
and
tister
shares,
cultivator
shovels
and
similar
cutting
points,
deposit
the
weld
metat
on one side
only
which
wilt
result
in a self.sharpening
edge
(fig.
4). The
softer base metal on the other side will wear
away
first and
leave a knife-like
edge
of hard
facing
materlai.
Parts that
must wear
uniformly
on both
sides shoutd
be hard
faced
on both
sides. The condition
of the worn
part
must afso be
taken
into
conslde_ation.
If the part
requires
a number
of
passes to bring
it up to the desired
thickness, use mild-steel
welding
rods
first;
then
cover
with
deposited
metal
from
hard
surfacing
rods.
tf the edge
is entirely
worn
away,
a
steel patch (cot to fit) may be welded
in place with mild_steef
electrodes,
then
hard
faced
(fig.
5). To prevent
distortion
when
hard
facing
smatl
parts,
peen
the
deposited
wetd
metat before
it cools,
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