A welding supervisor observes an excessive amount of spatter and a very harsh, unstable arc during a GMAW operation on mild steel with a 100% CO2 shielding gas. The welder is attempting to achieve a spray transfer mode. What is the most likely cause of these issues?

Question: A welding supervisor observes an excessive amount of spatter and a very harsh, unstable arc during a GMAW operation on mild steel with a 100% CO2 shielding gas. The welder is attempting to achieve a spray transfer mode. What is the most likely cause of these issues?

Answer options: ✅ The shielding gas is unsuitable for spray transfer mode.

• The wire feed speed is too low.
• The voltage setting is too high.
• The contact tip to work distance is too short.

Correct answer: The shielding gas is unsuitable for spray transfer mode.

Explanation: 100% CO2 shielding gas, while suitable for short-circuit and globular transfer, does not support true spray transfer due to its reactive nature and higher arc voltage requirements. Attempting spray transfer with 100% CO2 will result in a harsh arc, excessive spatter, and globular transfer characteristics instead of spray. Argon-rich mixtures are necessary for spray transfer.