In Nihon University, Conform continuous extrusion and new extrusion processes which are called multi-billet extrusion have been investigated last ten years. Conclad extrusion which was developed from Conform continuous extrusion, is applied to manufacturing trolley wire for train in Japan. The trolley wire which is copper covered steel wire has shorter life cycle than expected one because of corrosion for acid rain. The quality of welding part of copper must be improved. In this paper, it is investigated how to decrease involving oxide films in welding part by experimental method. On the other hand, the multi-billet extrusion is applied to manufacturing automotive frames, especially impact attenuators. The developed extrusion process has been done under experimental condition. However, it is capable to vary geometries of rib which is in the inside of closed profile extruded products by this process.