Fused Filament Fabrication Additive Manufacturing: Mechanical Response of Polyethylene Terephthalate Glycol

The additive manufacturing (AM) fused filament fabrication (FFF) technology is widely used today with different kinds of thermoplastic materials, including polyethylene terephthalate glycol (PETG). One of the major problems of parts produced by AM-FFF technology is the anisotropy of their mechanical properties. Therefore, it is very important to understand the effect of build strategy and post-processing on the mechanical properties and failure behavior of the FFF-PETG components. This research aims to examine the influence of 3D-print orientations, post-processing heat treatments and reinforcement of the material with carbon fibers, on the mechanical properties of FFF-PETG specimens. For this purpose, three different standard building orientations, flat, one-edge and upright specimens were printed. Tensile testing was carried out to obtain the mechanical properties of the FFF-PETG specimens for the different 3D-print orientations and post-processing. The specimens were characterized by visual testing, stereo microscopy, and SEM microscopy to examine the fracture surface after tensile test. The upright-melted specimens reached the same tensile strength as the as-printed flat and on-edge orientations specimens. The fracture surface of all three orientations is brittle and it typically starts by a mirror pattern that evolves into cleavage plates.