What does the last digit on the FCAW I.D system indicate?

The last digit in the FCAW (Flux-Cored Arc Welding) identification system is significant as it indicates the polarity and gas requirements for the electrode. In the FCAW system, electrodes are designed specifically to function optimally under certain conditions, including whether they are used with direct current (DC) or alternating current (AC), as well as the type of shielding gas that may be necessary during the welding process.

Understanding this specification is critical for welders, as using the wrong polarity or shielding method can lead to poor weld quality and may compromise the integrity of the weld. It's important for welders to select the right electrode not only based on the material being welded but also on these operational parameters to ensure effective and safe welding practices.

The other options, while they touch upon aspects related to electrodes, do not accurately reflect what the last digit signifies. For instance, wire type and voltage or thickness of material and amperage are factors of the overall welding process, but they are not specifically denoted by the last digit in the identification system.