794 Agricultural Mechanics and Technology Systems
Copyright Goodheart-Willcox Co., Inc.
the distribution of excess spatter around a
welded bead that lacks penetration. The
increased turbulence of a long arc created by
too much electrode angle also destabilizes
the O
2
-free shield. Too much electrode
angle results in a pointed effect in the ripple
of the fi nished bead. This is evident during
welding because the shape of the molten
weld pool will also be pointed.
A common mistake made by novice
welders is dropping the electrode angle to
get a better look at the weld. It is important
to learn to reposition your head and body in
order to see the weld instead of modifying
the electrode angle, Figure 29-27.
Electrode Motion
Welders develop their own individual techniques
for manipulating the electrode. Practicing helps you to
develop your own style, and studying the techniques
of good welders will improve your own.
Two types of beads are used in arc welding:
stringer beads and weave beads. Stringer beads are
straight, narrow beads made with minimal side-to-side
movement. Weave beads are wider weld beads that
are formed using a weave pattern (repeated electrode
motion). On material 1/4″ and thinner, weaving the
electrode is typically not necessary and creates a wider
bead than necessary. A single stringer bead is often
satisfactory for narrow groove weld joints.
To create a wider bead on thicker material, manipulate the electrode from
side to side in a continuous series of partially overlapping semicircles. This
technique results in a stepped pattern on the surface
of the bead. Limit the side-to-side motion of the weave
pattern to three times the diameter of the electrode
core. Different weave patterns are typically used for
different situations. See Figure 29-28. Practice leads to
skilled motion. In order to maintain penetration into
the base metal when you need to cover a wider area,
make multiple, overlapping passes.
When welding uphill, focus the heat from the
electrode on the sides of the joint. Move across the
middle of the joint slowly so the weld pool follows,
pausing slightly at the sides to ensure a smooth tie-in,
or blending, to the sidewall. If the layers of the
fi nished bead look like fi sh scales, forward movement
was too fast.
Filler metal
Electrode
Flux
Weld pool
Molten
droplets
Oxygen-free
shield
Slag
Bead
Arc
Base metal
10° to 15°
Goodheart-Willcox Publisher
Figure 29-26. Tilt the electrode 10° to 15° from perpendicular to
improve visibility of the pool.
Goodheart-Willcox Publisher
Figure 29-27. This unacceptable bead pattern was
caused by too much electrode angle.
A B C
Goodheart-Willcox Publisher
Figure 29-28. Weave patterns. A—Crescent, or
1/2 moon. B—Figure-eight. C—Zigzag.