Evaluation and Optimization of Thermoplastic Extrusion Parameters Influencing the Impact Resistance of Additively Manufactured Samples from PETG and Recycled PETG

Given the widespread use of additive manufacturing technologies through plastic extrusion and the need to use recycled plastic materials, this paper presents the results of the study on the evaluation and optimization of the influence of theromoplastic extrusion parameters on the impact resistance of additively manufactured samples from PETG and recycled PETG (rPETG) filament from the Everfil brand. In this context, 90 impact samples, 45 from PETG and 45 from rPETG, were additively manufactured by thermoplastic extrusion by the QIDI Q1 Pro printer, with the layer height deposited per pass L_h = 0.10/0.15/0.20 mm and the filling percentage I_d = 50/75/100%, which were subsequently subjected to impact testing by the HST XJJD-50T machine, using the 7.5J hammer and the impact speed of 2.9 m/s. In order to statistically evaluate the influence of the variable parameters of thermoplastic extrusion, layer height per pass (L_h) and filling percentage (I_d), on the impact strengths of additively manufactured PETG and rPETG samples, ANOVA and DOE analyses were performed using Minitab 20.3 software. Using the determined optimal parameters (L_h = 0.10 mm and I_d = 100%), impact strength values were obtained that were 210.87% higher than the impact strength values obtained from testing PETG samples. Considering the impact strength results obtained for the samples manufactured from rPETG and the fact that rPETG filament is 11% cheaper per kilogram than PETG filament, it can be concluded that the use of rPETG filament is a viable solution for the additive manufacturing of parts by thermoplastic extrusion.