©
COPYRIGHT 1998 THE ESAB GROUP, INC. LESSON
II
2.2.2.5
While polarity affects the penetration
and burn-off rate, the electrode coating also has
a strong influence on arc characteristics. Performance of individual electrodes
will be discussed
in succeeding lessons. 2.2.3
Electrode
Holder -
The electrode holder connects to the welding cable and con-
ducts the welding current to the electrode.
The insulated handle is used to guide the electrode
over the weld joint and feed the electrode
over the weld joint and feed the electrode into the weld
puddle as it is consumed. Electrode holders are available in different sizes
and are rated on
their current carrying capacity. 2.2.4
Ground
Clamp -
The ground clamp is used to connect the ground cable to the work
piece. It may be connected directly
to the work or to the table or fixture upon which the work is
positioned. Being a part of the
welding circuit, the ground clamp must be capable of carrying
the welding current without overheating
due to electrical resistance. 2.2.5
Welding
Cables -
The electrode cable and the ground cable are important parts of
the welding circuit. They must
be very flexible and have a tough heat-resistant insulation.
Connections at the electrode holder,
the ground clamp, and at the power source lugs must be soldered
or well crimped to assure low electrical resistance. The cross-sectional
area of the cable
must be sufficient size to carry the welding current with a minimum of voltage
drop. Increasing
the cable length necessitates increasing the cable diameter to lessen resistance
and voltage drop. The table in
Figure 4 lists the suggested American Wire Gauge (AWG) cable
size to be used for various welding currents and cable lengths.
Total Cable Length (Ground Lead Plus
Electrode Lead) Up
to 50 ft. Up to
100 ft. Up to
250 ft. Up to
500 ft. Cable
Voltage Cable
Voltage Cable
Voltage Cable
Voltage Size
Drop Size
Drop Size
Drop Size
Drop 20
to 180 #3
1.8 #2
2.9 #1
5.7 #0
9.1 180
Amps 30 to 250
#2 1.8
#1 2.5
#0 5.0
#0 9.9
200 Amps 60
to 375 #0
1.7 #0
3.0 #00
5.9 #000
9.3 300
Amps 80
to 500 #00
1.8 #000
2.5 #0000
5.0 #0000
9.9 400
Amps 100 to 600
#00 2.0
#0000 2.5
... ...
... 500
Amps Voltage
drops indicated do not include any drop caused by poor connection, electrode holder,
or work metal Welding
Service Range
(Amperes) Voltage
Drop Figured
At FIGURE
4 2.2.6
Coated
Electrodes -
Various types of coated electrodes are used in shielded
metal arc welding. Electrodes
used for welding mild or carbon steels are quite different than
those used for welding the low alloys
and stainless steels. Details on the specific types will be
covered in subsequent lessons.
welding earthing holder