4.2 Shielded Metal Arc Welding (SMAW)
Shielded metal arc welding (SMAW), or manually operated metal arc welding with covered electrodes,
is one of the most commonly used welding processes. It allows the greatest amount of flexibility in
terms of the range of materials and thicknesses that can be joined in all welding positions.
The SMAW process is the first one developed during the experimental stage of arc welding in the early
1920s. The knowledge of joint design, arc action, heat control and metal reaction gained from shielded
metal arc welding has been of great value in developing all other variations of the arc welding process.
4.2.1 Principles of Operation
In shielded metal arc welding, an arc is established between the end of a covered metal electrode and
the workpiece to be welded. The heat of the arc melts the surfaces of the joint as well as the metal
electrode. The filler metal is carried across the arc into the weld joint and mixes with the molten base
metal. As the arc is moved at a suitable travel speed along the joint, the progressive melting of the
metal electrode and the base metal provides a moving pool of molten metal, which cools and solidifies
behind the arc (Figure 4.1).