Droplet-on-demand metal additive manufacturing using a magnetostrictive actuator

Abstract

The molten metal droplet-on-demand (MMDoD) mechanism is one of the many advanced ways to achieve metal additive manufacturing (AM). A novel MMDoD mechanism is designed and developed using a magnetostrictive actuator to achieve a desktop-based metal AM system using a low input voltage circuit. The MMDoD mechanism further includes the use of a thermally insulating piston to protect the actuator from the heat of the molten metal pool. The oscillation of the piston in the MMDoD mechanism is used to generate the molten metal droplets. To generate reproducible molten metal droplets with the least geometrical variations, the effect of the input signal pulse shape, the input signal voltage amplitude, and stand-off distance between piston and nozzle entrance on the MMDoD mechanism performance is studied using high-speed videography. The input signal pulse shape is selected to be either the unfiltered signal (UFS) and low pass filtered signal (LPFS). Using UFS and LPFS, a parametric study of molten metal droplets size and its variation is conducted by varying the stand-off distance between the piston and nozzle and input signal voltage amplitude across the magnetostrictive actuator. To demonstrate the metal additive manufacturing using this system, a study is conducted to find the optimal gap between each droplet. Using the MMDoD system, molten metal droplets of uniform shape (571 μm) are ejected at fixed generation rate and deposited with an optimal gap to print conductive traces on a polymer substrate. As these conductive lines were printed using metal on polymer substrate, they could provide a new way to connect the electronic components to achieve AM of the electronic circuits.