Inertia friction welding joins two metal objects by spinning one at high rates of speed, then pressing it against the stationary piece. The friction heats both pieces and makes a weld sturdy enough for drive shafts, jet engines, spacecraft, and other machinery where joined pieces will endure tremendous stresses.
Here's some others (skipping to the good stuff):
This vintage video shows the process around the time it was first invented in 1960, though the film has a jump in it right at the best part!
• Inertia Friction Welder for Aerospace Component – Model 480B (YouTube / MTI)
