Evaluation and Optimization of Thermoplastic Extrusion Parameters to Improve the Dimensional Accuracy of Additively Manufactured Parts Made of PETG, Recycled PETG, ASA, and Recycled ASA

As additive manufacturing (AM) expands into high-end industries, ensuring both technical performance and dimensional accuracy remains a challenge. This paper addresses the challenge of integrating recycled materials into the field of plastic extrusion additive manufacturing technologies by conducting a study on the evaluation and optimization of thermoplastic extrusion parameters to improve the dimensional accuracy of additively manufactured parts from virgin and recycled polyethylene terephthalate glycol (PETG, rPETG) and acrylonitrile styrene acrylate (ASA), both in virgin and recycled form. To carry out the study, 180 three-point bending specimens were additively manufactured on the QIDI Q1 Pro 3D printer by thermoplastic extrusion of PETG, rPETG, ASA, rASA (45 specimens for each type of material), using the following variable parameters: layer height deposited in one pass L_h = (0.10-0.20) mm and filling percentage-I_d = (50-100)%. After manufacturing the specimens, the dimensional characteristics that will be determined by measurement were defined: L-length, WA-width A, HA-height A, WA'-width A', and HA'-height A'. Dimensional accuracy was assessed through 900 measurements using a DeMeet 400 coordinate measuring machine and analyzing the arithmetic means, dispersions, and mean square deviations. The results of the study confirm the superior dimensional stability of virgin materials (18.77-20.04%) compared to recycled materials. The analysis demonstrates that by optimizing the process parameters, filaments from recycled materials (rPETG and rASA) can achieve acceptable precision, with average deviations of 0.25-0.78% from the nominal dimensions. The present study validates the use of rPETG and rASA as a viable alternative for applications that do not require critical tolerances.