Investigating parameters to control 3D-printed extrusions at the micro-level using PLA and TPU

Purpose The primary aim of this research is to investigate the extent to which standard Fused Deposition Modelling (FDM) 3D printers can be explicitly controlled to fabricate flexible microstructures. Specifically, the study seeks to determine if manipulating automated toolpaths via geometric code (G-code) generation can consistently produce extruded strings significantly smaller than conventional nozzle diameters. Furthermore, it aims to explore multidisciplinary applications for these micro-lattices, transitioning them from theoretical novelties to functional components in fields such as biomedical engineering and filtration. Design/methodology/approach The methodology utilises FullControl G-code (FCG) to bypass conventional slicing software, explicitly programming hardware movements to control extrusions. An iterative experimental process was employed using a BambuLab P1P printer with a standard 0.2mm nozzle to test polylactic acid (PLA) and thermoplastic polyurethane (TPU). Parameters such as pull height, travel speed and extrusion rate were systematically varied and evaluated to achieve optimal string generation. These single micro-extrusions were then layered into complex, multi-axis planar meshes, which were subsequently baked to achieve structural adhesion. Findings The study demonstrates that carefully manipulated G-code enables the consistent production of precise microlattices with string diameters of 30–50 µm using a 0.2mm nozzle. PLA extrusions achieved diameters as fine as 20 µm with high consistency. TPU proved more challenging due to its flexibility and porosity, yet successfully yielded 30 µm strings under optimal parameters (1.2–1.6mm pull height). Applying radiant heat to the layered TPU strings ($180ˆ{\circ}C$ for 10 min) successfully induced uniform adhesion, transforming isolated strings into cohesive, functional planar meshes. Research limitations/implications A primary limitation is the difficulty in maintaining uniform string diameters across varying lengths within complex overlapping mesh designs. Furthermore, the employed stringing method lacks inherent tension during printing; combined with TPU's flexibility, this occasionally results in inconsistent gaps between woven strings rather than a perfectly rigid grid. The manual nature of programming G-code via FCG also introduces time constraints. Future research should investigate more precise heat application methods for adhesion and further refine the parameter algorithms to improve uniformity in multi-layered lattice structures. Practical implications The ability to fabricate micro-lattices on standard, consumer-grade FDM hardware significantly lowers the barrier to entry for micro-manufacturing, negating the need for highly specialised, expensive machinery. This methodology can be immediately applied to produce bespoke, flexible micro-structures for various industries. Proven use cases include high-resolution water or air filtration systems and acoustic dampening. In biomedical contexts, these scalable meshes offer a viable foundational framework for custom medical wound dressings or cellular tissue interaction arrays, where mechanical stretch is required for drug administration. Originality/value While previous research has demonstrated the use of FCG for micro-extrusions using rigid materials like PLA, this study pioneers the application of these techniques to elastic polymers, specifically TPU. By successfully establishing an optimised parametric framework for flexible micro-stringing, this paper proves that highly intricate, functional soft-material microstructures can be consistently fabricated without conventional slicing constraints. This expands the theoretical boundaries of standard FDM printing, bridging the gap between accessible desktop prototyping and advanced multidisciplinary fabrication.