Effect of infill pattern and density on tensile properties of 3d printed polylactic acid parts via fused deposition modeling (FDM)

Fused deposition modeling is a three-dimensional (3D) printing technology that usually performed with molten thermoplastic in a heated liquefied nozzle and deposited layer by layer on the printing platform. To reduce the usage of material and printing time via fused deposition modeling technology, a user typically specifies infill pattern and density. Nevertheless, it is crucial to know how these parameters affect the mechanical properties of the printed object. This study aims to investigate the tensile properties of polylactic acid 3D-printed specimens with different infill patterns and infill densities. Three infill patterns: linear, diamond, and hexagonal, with three infill densities: 25%, 50%, and 75%, were assessed. The specified infill patterns and densities were generated using slicing software MakerBot Makerware. A series of test specimens (ASTM D638 Type-I) with different infill patterns and densities were produced using the Flashforge Creator 3D printer. Tensile testing was conducted by using the mechanical testing machine according to ASTM D638. The results showed that the tensile strength and elastic modulus improve as the infill density increases for all examined infill patterns. The combination of 75% infill density and linear pattern depicts the highest tensile strength (42.67 MPa) and elastic modulus (1222.78 MPa). This combination (linear 75%) was the ideal infill pattern and density which have substantial strength, great stiffness, and less printing cost. The obtained data can be used as a reference for FDM 3D printer users in designing and manufacturing 3D printed objects.