Which GMAW transfer mode tends to produce the lowest heat input?

• A. Short circuit
• B. Globular
• C. Spray
• D. Pulsed

Answer: (A)

Heat input in gas metal arc welding is mainly determined by how long the arc stays across the workpiece and how much energy is delivered per transfer. In short‑circuit transfer, the metal is transferred by tiny droplets that form and bridge the gap with a very brief arc each time, so the arc on‑time is short and the voltage is low due to the short arc length. That combination keeps the energy delivered to the workpiece per transfer minimal, giving the lowest heat input among the transfer modes.

In contrast, globular transfer uses large droplets that transfer with longer, less controlled arcing, and spray transfer involves a continuous, high-current arc with high voltage, delivering more energy and thus more heat. Pulsed transfer can reduce heat input compared to a steady high-current mode by allowing intervals of lower current, but the inherent short arc duration of short‑circuit transfer generally results in the least heat input overall.