The influence of ultrasonic vibration-assisted micro-deep drawing process

Micro-deep drawing process combined with ultrasonic vibration were performed on three stainless steel 304 foils of different thicknesses to determine the influence of ultrasonic vibrations on micro-cup formability and the limit drawing ratio (LDR). An ultrasonic system that applies 20 kHz of oscillation at various amplitudes was developed, and a concentrator was used to transfer the oscillation from the transducer to the die. The LDRs of these foils were obtained with and without ultrasonic variations. The experimental results in this study showed that using ultrasonic vibration following the deep drawing processes increased the LDR from 1.67 to 1.83, from 1.75 to 1.92, and from 1.83 to 2 for thicknesses of 50, 75, and 100 mu m, respectively. The oscillation amplitudes had a significant effect on different thicknesses. An amplitude of 8.6 mu m could not be appropriately applied to foils because of the excessive oscillated force. The punch force also decreased as the oscillation amplitude increased because of reduced friction between the die and the blank. Based on these experimental results, this study showed that ultrasonic vibrations can be used to produce micro-cups that exhibit high application flexibility in miniaturization technology.