Box-Behnken modeling to optimize the engineering response and the energy expenditure in material extrusion additive manufacturing of short carbon fiber reinforced polyamide 6

The field of production engineering is constantly attempting to be distinguished for promoting sustainability, energy efficiency, cost-effectiveness, and prudent material consumption. In this study, three control parameters (3D printing settings), namely nozzle temperature, travel speed, and layer height (L_H) are being investigated on polyamide 6/carbon fiber (15 wt%) tensile specimens. The aim is the optimum combination of energy efficiency and mechanical performance of the specimens. For the analysis of the results, the Box-Behnken design-of-experiment was applied along with the analysis of variance. The statistical analysis conducted based on the experimental results, indicated the importance of the L_H control setting, as to affecting the mechanical strength. In particular, the best tensile strength value (σ_B = 83.52 MPa) came from the 0.1 mm L_H. The same L_H, whereas caused the highest energy consumption in 3D printing (E_PC = 0.252 MJ) and printing time (P_T = 2272 s). The lowest energy consumption (E_PC = 0.036 MJ) and printing time (PT = 330 s) were found at 0.3 mm L_H. Scanning electron microscopy was employed as a part of the manufactured specimens’ 3D printing quality evaluation, while Thermogravimetric analysis was also conducted. The modeling approach led to the formation of equations for the prediction of critical metrics related to energy consumption and the mechanical performance of composite parts built with the MEX 3D printing method. These equations proved their reliability through a confirmation run, which showed that they can safely be applied, within specific boundaries, in real-life applications.