vibration welding (also known as linear or friction welding) refers to a process in which two workpieces are brought in contact under pressure, and a reciprocating motion (vibration) is applied along the common interface in order to generate heat. the resulting heat melts the workpieces, and they become welded when the vibration stops and the interface cools. most machinery operates at 120 hz, although equipment is available that runs between 100–240 hz. vibration can be achieved either through linear vibration welding, which uses a one dimensional back and forth motion, or orbital vibration welding which moves the pieces in small orbits relative to each other. linear vibration welding is more common due to simpler and relatively cheaper machinery required.