Friction surfacing

Hereon/Arne Roos

Friction surfacing (FS) is a solid state joining process. In this process, a consumable stud is pressed under axial rotation with one end plane normal onto a substrate. The resulting frictional heat leads to softening and plasticising of the studs end plane, forming a viscoplastic shear boundary layer. Superimposing a horizontal translational movement of the substrate, generates, in combination with the torsion exerted on the plasticized stud material, the application of the stud material in the form of a layer onto the underlying substrate. The solidification of the applied material takes place both by cooling through heat conduction into the substrate and the jig as well as by heat transfer (convection) into the surrounding atmosphere. The main process parameters in FS are the horizontal traverse speed, the rotational speed of the stud and the axial contact force normal onto the studs end plane. Through FS, all material combinations known from radial friction welding, including dissimilar combinations, e.g. aluminium to steel can be joined. The build-up of multi-layer structures through FS is called solid state layer deposition (SSLD).