How does travel speed influence bead shape and penetration in MIG welding?

How does travel speed influence bead shape and penetration in MIG welding?

• A. Slower travel speeds produce a narrower bead
• B. Travel speed does not affect penetration
• C. Slower travel speeds increase penetration and bead height; faster speeds produce a narrower, flatter bead with less penetration
• D. Faster speeds produce a taller bead

Answer: (C)

Movement speed of the torch controls how much heat is deposited per unit length of weld. In MIG welding, heat input per length is higher when you move slowly because the arc sits over the same spot longer, dumping more energy into the metal. That extra heat makes the weld pool penetrate deeper into the base metal and grow taller, so you see a weld bead that is both higher and often wider. When you move faster, the arc spends less time at any one point, reducing heat input, which leads to shallower penetration and a bead that is flatter and narrower. So slower travel speeds increase penetration and bead height, while faster speeds produce a narrower, flatter bead with less penetration.

Movement speed of the torch controls how much heat is deposited per unit length of weld. In MIG welding, heat input per length is higher when you move slowly because the arc sits over the same spot longer, dumping more energy into the metal. That extra heat makes the weld pool penetrate deeper into the base metal and grow taller, so you see a weld bead that is both higher and often wider. When you move faster, the arc spends less time at any one point, reducing heat input, which leads to shallower penetration and a bead that is flatter and narrower. So slower travel speeds increase penetration and bead height, while faster speeds produce a narrower, flatter bead with less penetration.