Analysis of heat generation characteristics in ultrasonic welding of plastics under low amplitude conditions

Heat generation mechanism in processes of ultrasonic welding of plastics was not fully solved. Experiment results showed that increasing the amplitude increased the energy dissipated with the exception of low amplitudes, but no detailed analysis can be found in explaining this problem. This study proposed to investigate the heat-generating processes in such a condition with a new physically based model by solving the N-S equations. The increasing mean temperature profiles and the final temperature patterns are well agreed with previous researches. The results predicted that the distribution of heat generated in the welding zone was non-uniform. The highest temperature area changed its position with the variation of time and the amplitude of vibration. In low amplitude conditions, energy dissipation was found to firstly increase with a slight fluctuation, then decreased when the driven amplitude was larger than 5 μm. And different temperature distribution patterns were observed at these turning points.