Friction welding is a solid state welding process for metals and other materials. Solid state welding means that the material to be joined will not melt.
There are three different types of friction welding:
Rotary friction welding
Linear friction welding
Friction stir welding
The procedure for performing friction welds depends on the type of friction welds used:
Rotary friction welding: In rotary friction welding, at least one of the materials to be joined is circular. The circular material rotates rapidly using an electric clamping device. The material rotates at a very high speed and then separates or holds together after reaching the desired speed. Then, under certain pressures, the connected materials (at least one static material and at least one rotating material) are brought into contact with each other. The combination of speed and pressure produces heat and friction welding. After the rotation is complete and the welding is completed, the joint is allowed to cool for some time and the pressure generating force is eliminated. Depending on the application, post-weld processing may be required as welds are usually convex.
Linear friction welding: Linear friction welding is similar to rotary friction welding, with a few exceptions. First, neither part has to be round. Therefore, fast oscillating motion is used instead of rotational motion. Once the fast oscillating speed is reached, the parts are forced together and then cooled after the motion stops and the pressure-generating forces are removed. Depending on the application, post-weld processing may be required as welds are usually convex.
Friction stir welding: Friction stir welding uses non-expendable tools to generate the speed, pressure, and heat required for friction welding. During friction stir welding, the tool rotates quickly and inserts the weld. The tool continues to transfer pressure and speed as it moves along the length of the weld and welds the material together as it moves.
Many different types of metals can be joined by friction welding. In fact, some materials that cannot be joined by other welding methods can be joined by friction welding. Even some different welded joints can be friction welded. This is because solid state welding processes do not require fusion, so metal incompatibility encountered in the molten state is not an issue. Common metals joined by the friction welding process include
Many different types of steel
Various aluminium alloys
There is a lot more