Friction welding is a form of solid-state welding where the heat is obtained from the mechanically induced sliding motion between the parts to be welded. In solid-state welding, the joint is produced by applying pressure without significant melting of any of the work parts. Because no melting occurs, friction welding is not a fusion welding process in the traditional sense. The weld parts are held together under pressure. Generally, the frictional heat is generated by rotating one part against the other. When a certain temperature is reached, the rotational motion is seized, and the pressure applied welds the parts together. The bonding process is based either on deformation or on diffusion and limited deformation, so atomic movement (diffusion) creates new bonds between atoms of two surfaces. The time required to generate friction welds is measured in seconds.
Friction Welding – Advantages and Disadvantages
The combination of fast joining times (on a few seconds) and direct heat input at the weld interface yields relatively small heat-affected zones. If automatic loading and unloading devices are installed, the machines are completely automatic. Shielding gas, flux, and filler metal need not be used. This process successfully joins a wide range of similar materials and a number of dissimilar metals, including aluminum and steel. This is particularly useful in aerospace, which combines lightweight aluminum stock with high-strength steel.
On the other hand, the workpiece has its dimensional limitations. FRW is restricted mostly to round bars with similar cross-sections, pieces of other forms are still possible to wield, but it is much harder. Friction welding usually uses a specific rotary machine, which needs higher capital costs.
