Electric Field-Assisted Fused Filament Fabrication Process for Robust Additive Manufacturing in Unconventional Orientations

Fused filament fabrication (FFF) is one of the most widely used thermoplastic additive manufacturing techniques that have great potential for numerous applications. However, for more advanced additive manufacturing with unusual environments, such as in-space manufacturing, conventional FFF is limited by the lack of gravity and inconsistent nozzle standoff distance. Varying nozzle standoff distances in the FFF process typically result in problems with the adhesion of extruded material as well as dimensional and geometrical errors in the extruded material, which leads to a long setup time and a high failure rate. Conventional FFF typically needs continuous monitoring or human intervention to ensure successful printing. This paper innovated an electric field-assisted FFF (E-FFF) process for robust fabricating parts in unconventional printing orientations while eliminating the need for constant supervision and human intervention to maintain and adjust the z-height calibration. The E-FFF system integrates a high-voltage power supply with a conventional FFF printer to produce an electrostatic force between the nozzle and the build plate. The generated electrostatic force is capable of attracting the extruded molten polymer material towards the build plate even at larger z-heights of up to 1200 mu m under unconventional printing orientations. The effectiveness of the E-FFF process was demonstrated by comparing the E-FFF and conventional FFF processes. The results affirm the assistance of gravitational force on conventional FFF processes in the normal printing orientation. The novel E-FFF process with robust printing capabilities in the vertical and reverse orientations enables much larger nozzle standoff distances than that of the conventional FFF process, which exhibits great potential to be used in the micro/zero-gravity environment in the future. A two-dimensional finite element simulation model is used to understand the effects of applied voltage on the E-FFF process and calculate the electric field intensity. The simulation results showed that the electric field intensity of E = 1.27x106 V/m is sufficient for successful printing in all demonstrated printing orientations. (c) 2023 The Authors. Published by ELSEVIER Ltd. This is an open access article under the CC BY-NC-ND license (https://creativecommons.org/licenses/by-nc-nd/4.0)