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Chapter 5
Welding Processes
Welding processes usually utilise heat and/or pressure to
form the welded joint. The heat can come from various
sources such as an arc, flame, laser beam, electron beam,
friction, etc. We will look at the most commonly used arc
welding processes in this chapter.
Manual metal arc (MMA)/shielded metal arc
welding (SMAW)
Process description
Figure 5.1 shows the equipment used in this process. Fusion
is obtained from the heat of an arc formed between a
consumable flux-coated electrode and the workpiece. The arc
is protected from the atmosphere by a gaseous shroud
produced from the melting flux while the weld metal is
cleaned of contaminants by the flux, which forms a slag that
floats to the top of the weld (Fig. 5.2). This slag must be
removed after each weld run before the next pass is added to
prevent slag inclusions within the completed weld.
Figure 5.1 MMA welding equipment
49
Woodhead Publishing Ltd – A Quick Guide to Welding and Weld Inspection
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