Effect of line-width parameter on the tensile strength, surface profile and printing time of 3D printed PLA parts

This study investigates the effect of line-width values on the properties of 3D (three dimensional) printed PLA (polylactic acid) parts. 3D printing of parts was carried out by using low-cost cartesian type FFF (fused filament fabrication) desktop 3D printer. Brass nozzle with a diameter of 0.6 mm was used to print PLA parts. Parts having line-width values of 0.6 mm to 1.2 mm were printed and the effect of line-width values on the mechanical properties and printing time was investigated. Mechanical properties of 3D printed parts were determined by using tensile testing device (Zwick/Roell, Z250). Microstructures of 3D printed samples were investigated by using optical microscope (Leica, DM 2500). Printing time for each part was recorded during 3D printing process. Surface profiles of parts were investigated by using surface roughness tester (Mitutoyo SJ-210). Microstructural investigations showed that the voids were formed between adjacent deposited lines and the void content decreased from 5.89% to 5.13% with increasing line-width value up to 1.0 mm. Surface roughness parameter of Ra increased from 5.11±0.21 µm to 9.29±1.12 µm with increasing line-width. Tensile strength of 3D printed specimens showed a slight decrease with increasing line-width due to the presence of voids between adjacent u-turn sections. The tensile strength values were determined as 58.52±1.93 MPa and 46.54±1.18 MPa for specimens printed with line-width values of 0.6 mm and 1.2 mm respectively. SEM images of tensile fracture surface demonstrated that the main failure mechanism of the printed specimens was the rupture of deposited lines instead of fracture of inter-line bonding.