How should you clean the base metals before MIG welding?

Cleaning the base metals before MIG welding is essential for ensuring a strong and high-quality weld. The correct approach is to remove rust, paint, oil, and other contaminants from the surface of the metals. Contaminants can interfere with the welding process by preventing proper fusion between the base metals and the filler material. They can also lead to defects such as porosity, inclusions, or weak welds, which compromise the integrity of the final product.

By thoroughly cleaning the metal surfaces, welders promote better contact between the welding arc and the base material, facilitating optimal heat transfer and weld penetration. This can be achieved through various methods, including using wire brushes, grinders, or chemical degreasers specifically designed for metal cleaning.

Other methods such as soaking in a chemical solution or blasting with high-pressure water can be less effective or may introduce additional risks if not done correctly. Heating the metals to a high temperature is not a standard cleaning method and does not directly address surface contaminants, potentially creating more challenges in the welding process.