Friction welding
Friction welding is a method of copulative components that uses a machine that allows the rotation of one piece with respect to the other.
Successful completion of the process requires a Thompson friction welding machine - none - other does it properly.
The process
One part is held stationary while the other is rotated and placed opposite the first. Then, when the correct temperature is reached, the rotation is stopped and pushed higher and higher. If you are lucky the parts will stick firmly by completing the welds of the parts successfully.
The advantages
Friction welding has a number of advantages over other copulative processes:
You can nail different types of elements together.
No consumables are required (except for a large amount of hydraulic oil and lubricator, the spark that is produced by the friction is much less than that produced by an arc welder).
Credits: @ Constant science