6
Shielded Metal Arc Welder
For most applications, a 45º travel
angle and 45º work angle is sufficient.
For specific applications, consult an arc
welding handbook.
NOTE:
Right handed welders should
weld from left to right. Left handed
welders should weld from right to left.
The electrode should always point into
the weld puddle as shown.
ARC LENGTH
Arc length is the distance from the
work piece to the tip of the electrode,
the distance which the arc must travel.
A proper arc length is essential to
generate the heat needed for welding
(See Figure 9). An arc that is too long
produces an unstable arc, reduces
penetration, increases spatter, and
causes flat and wide beads. Too short
an arc does not create enough heat to
melt the work piece, the electrode has
a tendency to stick, penetration will be
poor, and uneven beads with irregular
ripples result. A proper arc should be
no longer than the diameter of the rod.
The sound of a proper arc is a steady,
crisp sizzle, similar to bacon frying.
TRAVEL SPEED
The travel speed is the rate at which
the electrode is moved across the weld
area (See Figure 9). When the speed is
too fast, the bead is narrow and bead
ripples are pointed as shown. When the
speed is too slow, the weld metal piles
up and the bead is high and wide. To
control travel speed, watch the width
of the weld bead (not the arc) when
welding. The weld bead is the orange,
molten metal behind the arc. The width
should be approximately twice the
diameter of the welding rod. Control
travel speed to obtain a consistent
bead width.
SLAG REMOVAL
Wear ANSI
approved safety
glasses (ANSI Standard Z87.1) and
protective clothing when removing
slag. Hot, flying debris can cause
personal injury to anyone in the area.
After completing the weld, wait for the
welded sections to cool. A protective
coating called slag now covers the weld
bead which prevents contaminants in
the air from reacting with the molten
metal. Once the weld cools to the point
that it is no longer glowing red, the
!
WARNING
slag can be removed. Removal is done
with a chipping hammer. Lightly tap
the slag with the hammer and break it
loose from the weld bead. The final
clean-up is done with a wire brush.
When making multiple weld passes,
remove the slag between each pass.
WELDING POSITIONS
Four basic welding positions can be used;
flat, horizontal, vertical, and overhead.
Welding in the flat position is easier than
any of the others because welding speed
can be increased, the molten metal has
less tendency to run, better penetration
can be achieved, and the work is less
fatiguing.
Other positions require different
techniques such as a weaving pass,
circular pass, and jogging. A higher skill
level is required to complete these welds.
All work should be performed in the
flat position if possible. For specific
applications, consult an arc welding
handbook.
Welding Guidelines
(Continued)
Normal Amps, Arc Length, Speed
Amperage Too Low
Amperage Too High
Arc Length Too Short
Arc Length Too Long
Speed Too Slow
Speed Too Fast
Workpiece
NOTE:
Weld bead width (W)
should be approximately
twice the diameter fo the
electrode rod used.
W
Figure 9 - Weld Appearance
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