This paper gives a description of an experimental study on the ultrasonic welding of metals. In ultrasonic metal welding, high frequency vibrations are combined with pressure to join two materials together quickly and securely, without generating large amount of heat. Horn, a key part of ultrasonic welding machine, should be designed very accurately to get the natural frequencies and vibration mode required. In this study, a horn is designed and developed for ultrasonic welding of Cu sheets. The tensile strength of welded parts is investigated for evaluation of weldability. Experimental parameters of welding test is set as follows; welding time 0.4s ~ 3.4sec. and vibration amplitude 40%, 60%, 80% and welding pressure 1.5bar, 2.0bar, 2.5bar. Samples are Cu sheets of 0.1mm thickness. Experimental results showed that the tensile strength increase as welding parameters increase, but when welding pressure is excessive, the tensile strength decrease due to fracture of the Cu sheets caused by over-welding. These results could be successfully applied for ultrasonic metal welding in various fields of manufacturing industry.

In this research, a new ultrasonic horn is designed and fabricated for welding thin Ni plates by vibration analysis. Two types of the horn tip are fabricated to evaluate the effect of horn’s tip on the weldability. Modal analysis, harmonic response analysis and FFT analysis are carried out for verifying the adequacy of the developed horn. To evaluate weldability of two types of horn tip, welding strength and the microstructure of the weld surface are experimentally investigated with various welding parameters such as pressure, time and vibration amplitude. Finally, the new horn with resonant frequency of 40 kHz is developed, and it is shown that welding strength and the microstructure of the weld surface are largely affected by horn’s tip shape.