Impact strength of 3D printed PLA using open source FFF-based 3D printer

Fused filament fabrication (FFF) has been used to manufacturing customizable products, which offers tremendous advantages due to its ability to create end-use products having any complex geometry in shorter lead-time. However, the application of the FFF process in functional parts is restricted due to the poor mechanical performance because of the nature of the process to form the object in a layer-by-layer manner. The mechanical properties of the FFF-printed object are largely influenced by the selection of the build parameters. Hence, in this study, the impact strength of the FFF fabricated PLA has been evaluated as a function of three build variables viz. raster angle, layer height, and raster width. The impact test specimen was fabricated at varying build conditions and tested as per the ASTM D256 standard. Results showed that the raster angle was found to be the most significant build parameter that affects the impact strength of a printed specimen. The higher impact strength was achieved at 0° raster angle with 300 µm layer height and 700 µm raster width. However, the results obtained may be effective only within the limit of parameters and ranges tested in this work. Furthermore, SEM analysis of fracture surface reveals that failure mode is influenced mainly by the raster angle. Apart from that, voids have also been displayed on the fractured surface that may act as stress concentration and reduce the strength.