Aluminum is ductile and malleable, so it is formable, thus reducing seams, but its softness comes with a lower melting point. For welders, this means that you need skill, knowledge of your machine, a deep understanding of your material, and acute attention to detail to produce a strong weld.
When aluminum is in contact with air, it naturally and immediately begins to produce a thin protective layer of aluminum oxide that is rustproof and corrosion resistant. This is wonderful for maritime vessels, but terrible for welding. That layer of aluminum oxide melts at 2500° F greater than aluminum. The heat discrepancy between a clean surface and an oxidized surface means that If the weld area has not been properly prepared by wire brushing the aluminum oxide film from the material, the base material can get scorched in an effort to produce a “puddle.” Furthermore, if oxygen enters the molten aluminum, the air bubbles begin the oxidation process. So aluminum TIG and MIG welding is performed inside of an artificial and pure atmosphere achieved by releasing inert or semi-inert gas from the torch to force outside contaminants such as oxygen, nitrogen, carbon dioxide, and water vapor from the weld area.
The mechanics of aluminum welding are not significantly more difficult than those for steel, but there is a narrower margin of error. “Metallurgy is a science and an art,” comments Mark Dziwulski, MAPC’s lead welder and Certified Weld Inspector (CWI). Aluminum welding demands finesse. MAPC has the experience and expertise to produce consistent and structurally sound aluminum welds, and we have become a leader in aluminum welding in the Mid-Atlantic region. “Welding aluminum, especially Gas Metal Arc Welding (MIG), is a challenging skill. Even in the Southern United States, where the bulk of this fabrication is done, good aluminum welders are hard to find. MAPC has them. We continue to hone our skill and train our team in new procedures and methods,” says Dziwulski.
Staying current is critical in the field of maritime welding, where aluminum is often the best material and MIG welding the best method. Many factors, especially material and thickness, determine the optimal welding method. MIG welding is best for thick material. Electrically charged wire is pushed into a weld joint. As the electric arc from the wire is tries to pass through the base metal, both the wire and the metal it is in contact with melt, creating a puddle of molten metal where both sides of the joint and the introduced filler wire become one.
Welders in our area do not often come in contact with aluminum material thick enough to warrant MIG, so it is rarely covered in regional trade schools or on the job. At MAPC, in-house training is key to our success as a leader in aluminum fabrication, and it creates a culture of improvement and cooperation. Investing in our employees allows us to tailor our skillset to industry needs and demonstrate to our talented workforce that we appreciate their abilities and want them to develop professionally. MAPC’s MIG team welding aluminum deck plates of the new Baltimore Water Taxis Our field is always advancing. We have the dynamic craftsmen with an aptitude for advanced technology and an appetite for new skills to drive innovation and stay ahead of the curve.
-Written by Abbey Hallock, MAPC employee and welder. Hallock has 8 years of experience in industrial and ornamental stainless steel and aluminum welding. She has worked in stick and MIG welding, but has placed emphasis on TIG throughout her career. She was instrumental in the first builds of the Baltimore Water Taxi.