In this study, a novel method of micro-forging and its application to mechanical fastening are proposed. We call this new process friction stir forming (FSF). The FSF process uses the heat generated by friction between a rotating tool and the material being forged. Trials with FSF and friction stir cladding of various aluminum alloys were carried out on a modified milling machine. The results of FSF performed on 6061, 2017, 2024, and 7075 alloys are discussed in terms of forgeability. In addition, grooved carbon steel plate has been successfully clad with aluminum alloy using the friction stir technique.