PRINTING CRITERIA FOR MATERIAL EXTRUSION OF HIGH TEMPERATURE THERMOPLASTIC COMPOSITES

摘要

Over the last decade, the popularity of 3D printing has increased dramatically. Material extrusion (ME) is the most common type of 3D printing, which typically involves extruding a molten thermoplastic material through a small orifice in a specific pattern. Once considered only a technique for making non-functional prototypes, a wide range of ME systems are now using high performance materials for a variety of functional applications. However, the process science underlying the extrusion of these materials is not well understood. Therefore, the authors have developed a "printability" framework for evaluating extrusion-based printing criteria for a wide range of thermoplastic materials based on fundamental viscoelastic and thermo-mechanical properties. The framework establishes processing boundary conditions for the four basic modes of the ME process: pressure-driven extrusion, extruded geometry definition, geometry stability, and component integrity. The governing equations for each of these modes have been applied to a variety of high performance materials across a number of ME-based printing platforms, including the large-scale 3D printing of carbon fiber reinforced composites.