Effects of variable gravity conditions on additive manufacture by fused filament fabrication using polylactic acid thermoplastic filament

Abstract

The capability to manufacture items in space is an exploration enabling advancement, and will be crucial for sustainable human exploration as we progress beyond Earth orbit. The extrusion based Fused Filament Fabrication (FFF) method using thermoplastics represents a robust and simple methodology applicable to printing parts for both current and future human spaceflight exploration missions. Understanding the performance and behaviour of the FFF process under varying gravity loads is therefore an important knowledge gap that needs to be addressed in order to fully appreciate the characteristics of space manufactured elements. At present, it is not well understood how gravity can influence the characteristics of such elements fabricated in variable gravity environments. In this study, we detail an experiment conducted on a parabolic flight campaign (PFC) wherein we produced a number of FFF polylactic acid (PLA) polymer test articles and compared them to terrestrially fabricated articles. We report on the methodology and the operational parameters used, as well as presenting an analysis of the samples via optical microscopy and tomography. Compressive, tensile and other technical properties are reported herein. A number of explanations are presented to explain the variance in specimens relative to terrestrial reference samples.