SHIELDED METAL-ARC WELDING
The shielded metal-arc welding process, referred to
as metallic-arc welding, arc welding, or stick welding,
is extensively used in welding ferrous and nonferrous
metals. It has many applications for producing a vast
assortment of metal products. Shielded metal-arc weld-
ing is found in the ship building industry and in the
construction industry for fabricating girders, beams, and
columns. Because it is easy to use and portable, shielded
metal-arc welding is universally used in the repair and
servicing of equipment, machinery, and a host of other
MANUAL SHIELDED METAL-ARC
Arc welding provides you the ability to join two
metals by melting them with an arc generated between
a coated-metal electrode and the base metal. The tem-
peratures developed by the arc can reach as high as
10000°F. The arc energy is provided by a power source
that generates either direct or alternating current. The
electrodes that carry the current produce a gas that
shields the arc from the atmosphere and supplies filler
metal to develop the weld shape.
A wide variety of welding equipment is available,
and there are many differences between the makes and
models of the equipment produced by the manufactur-
ers. However, all types of arc-welding equipment are
similar in their basic function of producing the high-am-
perage, low-voltage electric power required for the
welding arc. In this discussion, we are primarily con-
cerned with the typical items of arc-welding equipment,
rather than the specific types. For specific information
about the equipment your battalion or duty station has
available, consult the manufacturers instruction man-
ual. For additional operational information and safety
instruction, have your leading welding petty officer
explain the operation to you.
The basic parts of a typical shielded metal-arc weld-
ing outfit include a welding machine, cables, electrode
holder (stinger), and electrodes. The Steelworker also
requires a number of accessories that include a combi-
nation chipping hammer and wire brush, welding table
(for shopwork), C-clamps, and protective apparel.
Before we discuss the different types of welding
machines, you must first have a basic knowledge of the
electrical terms used with welding.
Many terms are associated with arc welding. The
following basic terms are especially important.
ALTERNATING CURRENT. Alternating cur-
rent is an electrical current that has alternating negative
and positive values. In the first half-cycle, the current
flows in one direction and then reverses itself for the
next half-cycle. In one complete cycle, the current
spends 50 percent of the time flowing one way and the
other 50 percent flowing the other way. The rate of
change in direction is called frequency, and it is indi-
cated by cycles per second. In the United States, the
alternating current is set at 60 cycles per second.
AMPERE. Amperes, sometimes called amps,
refers to the amount of current that flows through a
circuit. It is measured by an amp meter.
CONDUCTOR. Conductor means any material
that allows the passage of an electrical current.
CURRENT. Current is the movement or flow of
an electrical charge through a conductor.
DIRECT CURRENT. Direct current is an elec-
trical current that flows in one direction only.
ELECTRICAL CIRCUIT. Electrical circuit is
the path taken by an electrical current flowing through
a conductor from one terminal of the source to the load
and returning to the other terminal of the source.
POLARITY. Polarity is the direction of the flow
of current in a circuit. Since current flows in one direc-
tion only in a dc welder, the polarity becomes an impor-
tant factor in welding operations.
RESISTANCE. Resistance is the opposition of
the conductor to the flow of current. Resistance causes
electrical energy to be changed into heat.