The recent drive towards lightweight construction in the aerospace and automotive industries has been increased tremendously. Hence, suitable joining methods are necessary in order to reliably join materials like aluminium, copper etc., and to integrate them in engineering structures. Ultrasonic welding is a rapid manufacturing solid-state joining process that produces joints by the application of high frequency vibratory energy in the work pieces held together under pressure. It is a combination of both surface (friction) and volume (plasticity) softening effects. In this paper an effective methodology is developed to determine the optimum welding condition that maximizes the strength of the welded joints produced by ultrasonic welding by using Taguchi method. This method has been utilized to develop an effective model to predict weld strength by incorporating process parameters such as weld time, pressure and amplitude. Experiments were performed on bi-metals i.e. aluminium and copper of 0.5mm thickness specimen and an effective S/N ratio graphs were plotted with ANOVA for the inference to optimum result for Tensile-Shear strength.