What shielding gas setup is typically used for MIG welding aluminum in collision repair, and what equipment is often required?

• A. 100% argon shielding; AC-compatible power source and possibly a spool gun; sometimes a dedicated aluminum welder.
• B. 75% argon, 25% CO2; no special equipment.
• C. Oxygen shielding; standard DC power.
• D. Helium shielding; no power needed.

Answer: (A)

For MIG welding aluminum in collision repair, you use shielding gas of 100% argon because it provides the right arc stability and protection for the softer aluminum metal, while helping to keep the oxide from contaminating the weld. Aluminum requires AC power to help continually clean the oxide layer as the weld progresses, which is why an AC-capable power source is typically needed rather than DC only. Aluminum wire is soft and feeds poorly through a standard MIG gun, so a spool gun (or a push-pull feed system) is often required to deliver the wire reliably. Some shops also use or keep a dedicated aluminum welder to optimize drive systems, liners, and settings for consistent results and to avoid cross-contamination with steel equipment. The other gas options and setups don’t provide the same arc characteristics or oxide-cleaning action needed for aluminum, and they can lead to poor weld quality.