Interlayer temperature optimisation: an approach to maximising strength in the large-scale additive manufacture of fibre-reinforced PETG

Purpose The purpose of this study is to establish a reproducible method for quantifying the anisotropy between printed layers based on interlayer temperature and, using this information, provide recommendations for maximising print strength. Fibre-reinforced polymers are gaining popularity in large-scale material extrusion, which involves the layer-by-layer deposition of melted polymeric granulates. However, the mechanical performance of 3D printed components is highly influenced by the quality of the interfacial bond between layers. Material data sheets often do not report the extent of this anisotropy, thereby making it challenging to account for during the design stage without mechanical characterisation. Design/methodology/approach This study investigates the effect of the temperature at the interface between layers on the ultimate tensile strength of 3D printed parts made with post-industrial polyethylene terephthalate glycol. Findings This study identifies an optimal previous layer temperature ( T p ) of 130 ± 10°C, where interlayer bonding and material properties are maximised. An upper limit of 150°C is identified to avoid material sagging and a critical lower bound of approximately 113°C for achieving at least 80% of the maximum part strength. Moreover, this study underscores the importance of considering the effective cross-sectional area due to the ridged surface of printed samples. Recommendations include the use of infrared heat lamps for temperature control to ensure sustained interlayer bonding. Research limitations/implications The research does not address long-term effects and environmental factors affecting material properties, suggesting these as areas for future research. Originality/value This study’s findings are instrumental in establishing optimal printing parameters for large-scale material extrusion, thereby improving the reliability of 3D printed parts in industries like manufacturing and civil engineering.