(FSW) process, is a solid-state joining process that uses a non-consumable tool to join two facing workpieces without melting the workpiece material.

An improved modification of the standard friction welding technique is , a hybrid technology developed by EWI and MTI, which "uses an external energy source to raise the interface temperature of the two parts being joined, thereby reducing the process forces required to make a solid-state weld compared to traditional friction welding". The process applies to both linear and rotary friction