The document summarizes an experimental analysis of weld strength in friction stir welding of different grades of aluminum alloy using different tool geometries. Specifically, it analyzes welding 6061, 7005, and 8011 aluminum alloys with a cylindrical tool and tapered threaded tool. Tensile testing found that the tapered threaded tool produced stronger welds across all aluminum grades compared to the cylindrical tool, with strengths increasing up to 30%. This is because the threaded tool generates more friction and distributes the metal more evenly in the weld zone. Visual analysis also found the threaded tool produced better surface finish quality than the cylindrical tool.