Rotary Friction Welding


Rotary friction welding is a forge welding process, in which the heat for joining metallic workpieces is generated by a relative motion of two components while a load is applied. It works in the solid phase without reaching the melting point of the materials. Thus, even materials that cannot be joined by fusion welding can be welded. The weld region is normally narrow and shows a refined microstructure.


Relative Motion

Rotary friction welding can be performed in three ways:
  • Continuous drive friction welding
  • Inertia friction weling
  • A combination of the two energy variants.
In continuous drive friction welding, the rotation speed of the component is generated during the friction phase by a continuously driven motor. After the friction time, the relative motion is slowed down and a higher forging force is applied.
In inertia friction welding one of the components is connected to a flywheel, which is declutched from its drive when the right speed is reached. On contact with the workpieces, friction at the weld interface acts both as a heat source and a brake.

Applications

Engine valves and gear box lever

  

Inertia friction welded Airbag inflator

   

Friction stud welding of aluminium tubes

    


References

  1. Ruth M Stemple: Unconventional Welding Processes: A Bibliography. March 1973.