The principle of the superposition of ultrasonic frequency vibrations to conventional machining techniques is known and practiced since the 1950s under the name of ultrasonic machining. Using ultrasonics, many good properties appear including reduced thrust force, improved surface finish, increased productivity and reduced tool wear. In this thesis, I present a new assembly technique based on the same principles~: ultrasonic press-fitting. Feasibility and advantages are demonstrated through experiments under industrial conditions. The technological breakthrough is such that for same components and process parameters, assembly strength is up to five times higher than that of a conventional assembly for an insertion force divided by a factor between two and ten! These gains, also observed for ultrasonic stamping, make possible innovation at every level of a production system that operates within (sub-)millimetric scale: from design to manufacturing and assembly. I give for each of these levels a concrete example of an industrial application.