What is a spool gun and when is it recommended in automotive MIG welding?

• A. A spool gun feeds aluminum filler through a separate tube to the weld, recommended for long runs or when base material is aluminum to avoid feedability issues.
• B. A spool gun is a type of safety device used to fight fires in welding shop.
• C. A spool gun increases the welding current automatically.
• D. A spool gun is used only for carbon steel.

Answer: (A)

A spool gun is a separate wire-feed unit that feeds the filler wire directly from a spool mounted near the torch, using a short feed tube to bring the wire to the weld. This setup is especially helpful with aluminum. Aluminum filler wire is softer and more prone to feeding problems when it has to travel a long distance through a standard MIG feeder and liner. By keeping the spool close to the gun and providing its own drive mechanism, the feed path is shorter and less prone to snagging, tangling, or inconsistent wire speed. That makes welds more reliable on longer runs or when you’re welding aluminum base material, which is common in automotive repairs. It’s not about increasing welding current, it isn’t a safety device, and it isn’t restricted to carbon steel—the spool gun’s primary benefit is improved, stable aluminum wire feeding.