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FCAW is similar to GMAW and the GMAW machines can be used. However, the wire electrode is flux cored rather than solid; that is, the electrode is a metal tube with flux wrapped inside. The functions of the flux are similar to those of the electrode covering in SMAW, including protecting the molten metal from air. The use of additional shielding gas is optional as shown in Figure 1.21.

Figure 1.21 Flux‐cored arc welding: (a) overall process; (b) welding area enlarged.

Figure 1.22 compares gas shielding in several arc welding processes. In SMAW and FCAW, the decomposition of the flux produces the shielding gas right at the arc and next to the weld pool. Thus, even when welding in the presence of flowing air, such as winds in field welding, the shielding gas can still protect the molten metal reasonably well. In GMAW and GTAW, however, the shielding gas may be blown away by winds immediately after exiting the gas nozzle. The molten metal may not be protected effectively by the shielding gas.

Figure 1.22 Sensitivity of gaseous shield of molten metal to wind or draft.