Mechanical properties optimization for PLA, ABS and Nylon

The mechanical characteristics and properties of 3D printed parts are highly influenced by the printing pa-rameters, the printer characteristics, the raw material and the capabilities of the G-code generating software. This work is distinguished by presenting a systematic study to optimize the mechanical properties of PLA, ABS and Nylon + carbon fiber (N + CF) parts manufactured by 3D fused deposition modeling (FDM) printing. To perform the optimization and statistical analysis of the effect of 3D printing parameters (geometric pattern, infill per-centage, printing direction and the layer height) on ultimate tensile stress (UTS) and modulus of elasticity (E), two nk designs of experiments (DOE) were systematically applied. In this way, the printing parameters that maximize the UTS and those that are not significant for the three materials were defined which is the main contribution of this work. Additionally, a correlation analysis between density and UTS is presented (R2 =94.4 %). In the first DOE it was found that the material and the percentage of infill (33 %, 66 % and 100 %) are decisive factors in the impression; the geometric pattern (tridimensional, hexagonal and linear) is no longer relevant and is not considered in the following analysis. In a second DOE it was found that by decreasing the layer height from 0.18 mm to 0.14 mm and modifying the printing direction from 0 degrees /90 degrees to + 45 degrees/-45 degrees there is an increase in the ultimate tensile stress (UTS) for all three materials. The specimen with the highest UTS reached 85 MPa, which was printed with N + CF linearly with 100 % infill, with 0.14 mm printing layer height and + 45 degrees/-45 degrees in the printing direction. Through systematic analysis by DOE, it was possible to achieve higher UTS values than their own filaments in the case of N + CF and PLA by 49 % and 18 %, respectively, while for ABS its value is very close to the filament. In conclusion, an algorithm is presented to systematically analyze by DOE to evaluate the hypothesis of achieving a higher UTS than the filament for ABS, PLA and N + CF specimens manufactured by 3D printing.

Automated summary

This study systematically optimized the mechanical properties of PLA, ABS, and N + CF parts manufactured by 3D FDM printing, and presented an algorithm for systematic analysis. It was found that material and percentage of infill were decisive factors in the printing process, and decreasing layer height and modifying printing direction increased the ultimate tensile stress for all materials.