How does increasing wire feed speed (WFS) affect heat input and weld penetration in GMAW?

• A. Decreases current and heat input, reducing deposition and penetration
• B. Increases current and heat input, usually increasing deposition and penetration
• C. Has no effect on heat input or penetration
• D. Increases deposition but reduces penetration

Answer: (B)

Increasing wire feed speed raises the welding current in GMAW. With more current, more heat is delivered to the weld area, so heat input goes up. That additional heat typically drives a deeper molten pool, increasing weld penetration, and also melts and transfers more filler metal per unit time, boosting deposition. In practice, this relation holds when voltage and travel speed are kept constant—the bigger the current, the hotter the arc and the deeper the penetration, up to limits where too much heat can cause defects.