Friction stir welding was developed in the 90’s, but Spacex perfected its own technique to adapt the technology to large sheets of metal like the ones use for the aluminium tank of their rockets. They developed their own technique and equipment and perfected the process. Here is Musk explaining the process to Wired back in 2012:
Instead of riveting the ribs and hoops, you use a special machine that softens the metal on both sides of the joint without penetrating it or melting it. Unlike traditional welding, which melts and potentially compromises some metals, this process works well with high-strength aluminum alloys. You wind up with a stiffer, lighter structure than was possible before. And your material loss is maybe 10 percent, just for trimming the edges.
Friction stir welding was developed in the 90’s, but Spacex perfected its own technique to adapt the technology to large sheets of metal like the ones use for the aluminium tank of their rockets. They developed their own technique and equipment and perfected the process. Here is Musk explaining the process to Wired back in 2012:
Instead of riveting the ribs and hoops, you use a special machine that softens the metal on both sides of the joint without penetrating it or melting it. Unlike traditional welding, which melts and potentially compromises some metals, this process works well with high-strength aluminum alloys. You wind up with a stiffer, lighter structure than was possible before. And your material loss is maybe 10 percent, just for trimming the edges.