Welding Technology Fundamentals 62
Figure 5-26. The chisel end of a chipping hammer being used
to remove the slag from a finished SMAW weld.
Figure 5-27. A wire brush is used to clean the weld after slag
has been removed.
Shielded metal arc welding (SMAW) is a welding process in which the base metals are heated to fusion
or melting temperature by an electric arc. The arc is created between a covered metal electrode and the
base metal. The shielding gas is created as the flux covering on the electrode melts. The flux solidifies
and forms a slag that protects the weld metal while it cools. The melting electrode wire furnishes filler
metal to the weld.
When direct current flows from the electrode to the base metal, it is referred to as direct current electrode
negative or direct current straight polarity.
When direct current flows from the base metal to the electrode, it is referred to as direct current electrode
positive or direct current reverse polarity.
Direct current flows in only one direction. Alternating current reverses direction at a set frequency,
usually 60 cycles per second.
A welding outfit consists of the equipment required to actually create a weld. A welding station also
includes tools, supplies, and other items required to make welding safe and comfortable.
Arc welding machines used for SMAW produce a constant current (CC).
The electrical cable that connects the electrode holder to a welding machine is the electrode lead. The
workpiece lead (ground) is the electrical cable that connects the base metal to the welding machine.
A #10–#14 filter lens should be used for SMAW. A darker lens is required when using larger diameter
electrodes.
SummaryyrammuS Summary