The Influence of Process Parameters on the Microstructure and Properties of PETG + GF Composites via Fused Granule Fabrication

ABSTRACT Fused granule fabrication (FGF) is suitable for high‐efficiency forming of short‐fiber‐reinforced thermoplastic composites, but the increased extrusion flow and screw/nozzle interaction may cause fiber breakage, pore retention, and unstable mechanical properties. In this study, cost‐effective PETG+GF composites were selected to investigate the effects of layer height, nozzle diameter, printing speed, and annealing treatment on microstructure and mechanical properties. The results show that increasing the nozzle diameter reduces deposition laps and facilitates pore elimination, thereby improving densification and tensile performance. A maximum tensile strength of 66.69 MPa was achieved at a nozzle diameter of 0.8 mm with a raster angle close to 0°, comparable to that of some PETG+CF composites. Annealing at 65°C for 240 min further regulated pore evolution and increased tensile strength by 11.17%. Moreover, increasing the printing speed improved tensile properties by up to 13.36%, demonstrating the feasibility of simultaneously improving forming efficiency and mechanical performance. This study provides an effective process control strategy for high‐performance PETG+GF composites prepared by FGF.