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are identified by the wire diameter and by a series of letters and numbers. The letters and
numbers identify the metal alloy and the intended use of the electrode.
The metal wire core works as a conductor of the current that maintains the arc. The core wire
melts and is deposited into the welding pool.
The covering on a shielded metal arc welding electrode is called flux. The flux on the
electrode performs many different functions:
•
producing a protective gas around the weld area.
•
providing fluxing elements and deoxidizers.
•
creating a protective slag coating over the weld as it cools.
•
establishing arc characteristics.
•
adding alloying elements.
Covered electrodes serve many purposes in addition to adding filler metal to the molten
pool. These additional functions are provided mainly by the covering on the electrode.
ARC (STICK) WELDING FUNDAMENTALS
ELECTRODE SELECTION
As a general rule, the selection of an electrode is straight forward, in that it is only a matter of
selecting an electrode of similar composition to the parent metal. However, for some metals there
is a choice of several electrodes, each of which has particular properties to suit specific classes of
work. It is recommend to consult your welding supplier for the correct selection of electrode.
ELECTRODE SIZE
The size of the electrode generally depends on the thickness of the section being welded and
the thicker the section the larger the electrode required. The table gives the maximum size of
electrodes that may be used for various thicknesses of section based on using a general-
purpose type 6013 electrode (See Table 2).
WELDING CURRENT (AMPERAGE)
Correct current selection for a
particular job is an important
factor in arc welding. With the
current set too low, difficulty
is experienced in striking and
maintaining a stable arc. The
electrode tends to stick to the
work, penetration is poor and
beads with a distinct rounded profile will be deposited. Too high current is accompanied by
overheating of the electrode resulting undercut and burning through of the base metal and
producing excessive spatter. Normal current for a particular job may be considered as the
maximum, which can be used without burning through the work, over-heating the electrode or
producing a rough spattered surface. The table shows current ranges generally recommended for
a general-purpose type 6013 electrode (see Table 2).
ARC LENGTH
To strike the arc, the electrode should be gently scraped on the work until the arc is established.
There is a simple rule for the proper arc length; it should be the shortest arc that gives a good
surface to the weld. An arc too long reduces penetration, produces spatter and gives a rough
surface finish to the weld.
An excessively short arc will cause sticking of the electrode and result in poor quality welds.
General rule of thumb for down hand welding is to have an arc length no greater than the
diameter of the core wire.
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145A MULTI-PROCESS MIG-ARC-TIG WELDER
AVERAGE THICKNESS
OF MATERIAL
0.03 to 0.07 in.
0.07 to 0.19 in.
0.19 to 0.31 in.
0.31 in. greater
MAXIMUM RECOMMENDED
ELECTRODE DIAMETER
0.09 in.
0.12 in.
0.15 in.
0.19 in.
8619470
CURRENT RANGE
(AMPS)
60 to 100A
100 to 130A
130 to 165A
165 to 260A
Table 2
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