Figure 7-56.Steel electrode being used to cut plate.
Figure 7-55.V-groove gouged in 2-inch-thick carbon steel.
METAL ELECTRODE ARC CUTTING
. Always cut away from the operator as molten
metal sprays some distance from the cutting ac-
tion. You may use this process to cut or gouge
metal in the flat, horizontal, vertical, or overhead
AIR CARBON-ARC GOUGING
Air carbon-arc gouging is useful in many various
metalworking applications, such as metal shaping and
other welding preparations. For gouging, hold the elec-
trode holder so the electrode slopes back from the direc-
tion of travel. The air blast is directed along the electrode
toward the arc. The depth and contour of the groove are
controlled by the electrode angle and travel speed. The
width of the groove is governed by the diameter of the
When cutting or gouging a shallow groove on the
surface of a piece of metal, you should position the
electrode holder at a very flat angle in relation to the
work. The speed of travel and the current setting also
affect the depth of the groove. The slower the movement
and the higher the current, the deeper the groove. An
example of a V-groove cut made in a 2-inch-thick mild
steel plate by a machine guided carbon-arc air-jet is
shown in figure 7-55.
Metal can be removed with the standard electric arc,
but for good gouging or cutting results, you should use
special metal electrodes that have been designed for this
type of work, Manufacturers have developed electrodes
with special coatings that intensify the arc stream for
rapid cutting. The covering disintegrates at a slower rate
than the metallic center. This creates a deep recess that
produces a jet action that blows the molten metal away
(fig. 7-56). The main disadvantage of these electrodes
is that the additional metal produced must be removed.
These electrodes are designed for cutting stainless
steel, copper, aluminum, bronze, nickel, cast iron, man-
ganese, steel, or alloy steels.
Atypical gouge-cutting operation is shown in figure
7-57. Notice that the angle between the electrode and
plate is small (5 degrees or less). This makes it easy to
remove the extra metal produced by the electrode.
The recommended current setting is as high as the
electrode will take without becoming overheated to the
point of cracking the covering. For 1/8-inch electrodes,
the setting ranges between 125 and 300 amperes; for
5/32-inch electrodes, the setting ranges between 250 and
375 amperes; and for 3/16-inch electrodes, the setting
ranges between 300 and 450 amperes. Use a very short
arc, and when cutting takes place underwater, the coat-
ing must be waterproof.