FCAW and GMAW are welding processes that operate on DC polarity and never on what?

FCAW (Flux-Cored Arc Welding) and GMAW (Gas Metal Arc Welding) are welding processes that are primarily designed to operate using direct current (DC) polarity. When we discuss AC (Alternating Current) in this context, it's crucial to understand that these specific processes do not utilize it as a power source for several reasons.

One primary requirement for FCAW and GMAW is a consistent arc and stable heat input, which are achieved more reliably with DC polarity. AC, while suitable for some types of welding (like GTAW for aluminum), tends to fluctuate in polarity, which can lead to inconsistencies in the arc stability and heat input that are needed for optimal weld quality in FCAW and GMAW.

The use of DC enhances the efficiency of these processes, allowing for faster travel speeds and better penetration of the weld. This reliability in the welding process helps manufacturers produce high-quality welds and meet stringent fabrication standards set forth in welding codes.

Therefore, the answer indicating that FCAW and GMAW never operate on AC current is accurate due to the inherent nature of how these processes are designed to function most effectively.