Continuous filamentary extrusion of metallic structures at micro-meso scale has the potential to transform the current state-of-art high resolution additive manufacturing of metals. These could open novel application domains in the fields of antennas, sensors, wearable devices, energy devices, biomedical devices, etc. However, currently available extrusion-based techniques for metals and alloys are limited to planar printing, limiting their applicability as an industrially accepted manufacturing technique. Furthermore, currently there are no studies fundamentally investigating the extrusion mechanism of liquid metals and understand the process parameter dependencies on the extruded structures. While polymer-based extrusion is very well established, the same body of knowledge and equipment cannot be applied to extrude print liquid metallic structures due to their significantly different thermofluidic behavior.

This Ph.D. research objective is to bridge the above-mentioned gap by developing equipment and fundamentally investigating the extrusion mechanism that would aid in transforming extrusion based additive manufacturing of metallic structures at micro-meso scale as an industrially acceptable technique. Here we demonstrate a novel 3D printing system through which we were able to realize freeform non-planar filamentary structures that were not possible before due to system limitations. We then develop a numerical model to study the thermal mechanisms of the extrusion process and understand the correlation between the process parameters and the printed structures. After which we closely investigate the alloy deposition mechanism and determine that the oxide skin formed by non-noble liquid metals plays a critical role in extrusion printing of liquid metals. We finally demonstrate printing of various alloy compositions and pure metals to validate that non-noble metals and alloys can be additively manufactured using extrusion-based techniques.