Finite element simulation of ultrasonic embossing on polymers

Abstract

This paper presents a simulation of polymeric embossing process utilizing ultrasonic vibrations. The embossing process is to use heat to soften the polymeric substrate around the die so that the polymer work piece is able to create the required feature of the die. However, the displaced materials from the embossing process will affect the overall dimensions of the embossed feature in the polymer with respect to the die's design. This investigation indicates that the heat generated at the polymer and die interface is caused by hysteresis heating which is a result of the mechanical vibrations generated by the ultrasonic horn. The rapid process of ultrasonic embossing has resulted in defects. This difficulty is usually addressed by experience or trials and errors through fine-tuning the processing parameters. Through finite element analysis, the ultrasonic embossing process can be visualized graphically. The flow pattern of the softened polymer during the embossing process can be visualised through simulation based on the input parameters, feature dimensions and polymer type. Comparisons are made between simulation and physical embossing experiment. This investigation indicates that FEM could provide a better understanding of the embossing process.