LESSON VII
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COPYRIGHT 2000 THE ESAB GROUP, INC. Turn
Pages 7.5.0.1
Self-shielded electrodes are extensively
used in mild steel welding applications. A
few electrodes are available containing 1% nickel for improved strength and impact
properties. 7.5.0.2
Being a continuous welding process,
self-shielded electrodes are capable of higher
deposition rates than coated electrodes, and are designed for specific applications
such as general purpose welding, assembly
and repair welding, out-of-position welding, and
high deposition welding. Some electrodes are specifically designed for welding
lighter gauge
materials (.047" to 3/16" thickness) at high speeds. Self-shielded electrodes
are available
in diameters ranging from .030" to 5/32". 7.5.1
Electrode
Extension -
Self-shielded flux cored electrodes utilize a longer elec-
trode extension than the gas shielded
types. The electrode extension ranges from 1/2" to
3-3/4" depending on the electrode type,
and the application. The longer length of wire beyond
the contact tip decreases the arc voltage, since the additional wire acts as a
resis- tance.
It causes the wire to heat and is accompanied by a lower welding current
(amper- age).
This lower voltage and amperage results in a narrow, shallow weld bead that
does not melt
as much of the base metal, allowing the process to be used on welding thinner
material and for poor fit-up applications.
If the welding current and voltage are increased, the
deposition rate will increase, and to a lesser degree, so will the penetration.
It is impor- tant
that the manufacturer’s recommendations for each type and size of electrode
are followed.
7.5.2
All-Position
Electrodes -
The self-shielded all-position electrodes utilize direct
current, straight polarity (electrode
negative). Penetration is low, making them suitable for
bridging gaps in poor fit-up applications.
Optimum welding current and amperage settings are
lower than those with the gas shielded types. The .068" and 5/64" diameters
are most commonly
used for out-of-position work, although the 3/32" may be used in some cases.
Electrical stickout between 1/2" to
1" is recommended for these wires. 7.5.3
High
Deposition Types
- The high deposition types of self-shielded wires utilize
long electrical stickout (1-1/2" to
3-3/4") and most use reverse polarity (electrode positive).
Designed for use in the flat or horizontal
positions only, they are commonly available in the 5/64",
3/32", 7/64", and .120" diameters.
