Which factors should be considered to compare heat input across two GMAW setups?

• A. Ambient temperature and shielding gas color
• B. Filler wire diameter and shielding gas type
• C. Volts, Amps, and travel speed
• D. Torch angle and tip shape only

Answer: (C)

Heat input is the energy delivered to the weld per unit length, and in GMAW that energy is governed by the arc’s electrical settings and how fast you move the arc along the joint. The energy per unit length rises with higher voltage and higher current, and it falls as you increase the travel speed. So comparing heat input across two setups comes down to looking at volts, amps, and travel speed, since these directly set how much energy passes into the metal per unit length of weld.

Ambient temperature and shielding gas color don’t change the energy delivered by the arc. Filler wire diameter and shielding gas type can influence deposition rate and arc behavior, but they don’t define the heat input the way voltage, current, and travel speed do. Torch angle and tip shape affect how heat is distributed, which affects penetration and bead shape, but not the fundamental amount of energy being input per unit length.