An explainer on this wonder-material for some carmakers.
A sheet of aluminum is formed much the same way as steel: ingots are heated to 1,000 degrees Fahrenheit and rolled between pins into sheets. From there they can go into beer cans or cars, but the process is the same—just the chemical composition changes. An automobile can carry up to 15 different aluminum alloys, all strengthened with copper and silicon.
In addition to stamping sheets of metal into shape via a press, aluminum is usually cast in a die. Casting is the simplest, most common, and most inexpensive way to produce aluminum, according to The Aluminum Association. Aluminum has been cast into engine internals for decades, as well as transmission enclosures and engine blocks. Exterior panels like hoods and doors are stamped though.
Aluminum doesn't weld easily. Oxide on the material's surface traps in gases, creating holes inside the weld and weakening it. Instead, aluminum panels are joined together by industrial-strength adhesives and self-piercing rivets. As a result, some carmakers have had to retool their assembly lines, replacing traditional spot welders with bonding and laser welding equipment, and spending millions in the process.
Rivets have replaced spot welding for nearly all aluminum operations—they punch through and fasten metal pieces without heat, sparks, or fumes. And, they're just as strong as spot welds, but require just one step. They can also be readily checked by robots for precision—which is vital when working with such new technology.
These are fasteners that drill through multiple sheets of aluminum and secure them in the process. A screw rotates and generates heat as it penetrates through multiple metal sheets. As the metal cools, it contracts around the screw to create a tough bond. European carmakers have used this technology for nearly two decades, leveraging their own aluminum expertise. They're easy to install and require no drilling beforehand, simplifying the assembly process.
Since aluminum isn't magnetic, factories must rely on vacuum pumps instead of magnets to move the pieces from place to place. Other changes on the factory floor can lead to unexpected benefits. When Ford upgraded its River Rouge plant to begin production of the aluminum-bodied F-150, smaller robots replaced the cumbersome spot-welding robots and their safety cages. This made the floor less crowded, gave engineers easier access to tooling, and cut down on noise.