Effect of processing parameters on tensile properties of FDM 3D printed of PLA specimens

Fused Depositional Modeling (FDM) is one of the common methods for 3D printing of polymers, which is expanding in various industrial applications and engineering applications due to its ability to make complex parts. The mechanical properties of 3D printed parts strongly depend on the correct selection of processing parameters. In this study, the effect of three important parameters such as infill density, printing speed and layer thickness are investigated on the tensile properties of PLA specimens. To this end, standard specimens with four infill densities of 20%, 40%, 60% and 80%, two speeds of 20 mm/s and 40 mm/s, and two thicknesses of 0.1 mm and 0.2 mm are printed and tested under quasi-static tensile test. In all printed specimens, the print angle is assumed ±45°. Experimental results showed that the increase of infill density up to 60% has significant increase on the modulus of elasticity, ultimate strength, and failure strain. But at infill density of 80% with the highest stiffness to weight and strength to weight ratios, the failure strain has decreased up to 31.9% in comparison to infill density of 60%. Reducing printing speed from 40 mm/s to 20 mm/s causes the increase of stiffness, ultimate strength and failure strain up to 7.8%, 9.7% and 1.6%, respectively. Moreover, it is observed by reducing the layer thickness from 0.2 mm to 0.1 mm, modulus of elasticity increases 18.7% and failure strain decreases 53.4%.