WELDING OPERATIONS I - OD1651 - LESSON 1/TASK 2
(3) Cutting with the Electric Arc.
(a) Electric arc cutting is a procedure whereby metal is cut
using the heat of an arc maintained between the electrode and the
Three procedures described in the following
subparagraphs are used in cutting with the electric arc.
(b) Carbon-arc cutting is a process whereby the cutting of
metals is accomplished by progressive melting with the heat of an
electric arc between a metal electrode and the base metal.
The carbon arc is used under some conditions in
conjunction with a jet of compressed air for the removal of
defective austenitic (corrosion resistant) weld metal.
with the carbon arc is used for cutting both ferrous and
nonferrous metal, but does not produce a cut of particularly good
The electrodes are either carbon or graphite,
preferably with a pointed end to reduce arc wandering, and thus
produce less erratic cuts.
(c) Metal-arc cutting is a process whereby the cut is produced
by progressively melting the metal.
Direct current straight
polarity is preferred for this process.
ranging in diameter from 1/8 to 1/4 inch are used; larger
diameters are not satisfactory because of excessive spatter. The
thickness of the metal that can be cut by the metal-arc process
is limited only by the length of the electrode. The coating on
the electrode serves as an insulator between the core of the
electrode and the side wall of the cut, resulting in less short-
circuiting against the kerf. Cuts made by the metal-arc process
are less ragged than those produced with carbon-arc, but they
must still be prepared by grinding or chiseling before rewelding
(d) Oxy-arc cutting is accomplished by directing a stream of
oxygen into the molten pool of metal. The pool is kept molten by
the arc struck between the base metal and the coated tubular
The rod is consumed during the cutting operation.
The tubular rod also provides an oxidizing flux and a means of
converging oxygen onto the surface being cut. The