Polylactic acid (PLA) is a widely used biodegradable polymer in fused filament fabrication (FFF) 3D printing, yet its mechanical performance often limits its use in load-bearing applications. Improving the impact strength of PLA components remains a critical challenge in additive manufacturing. This study addresses the question: how can key FFF parameters be optimised to significantly enhance the impact strength of PLA parts? To this end, three influential process parameters – layer height, nozzle temperature and infill density – were systematically varied and analysed using the Taguchi method with an L9 orthogonal array. Impact strength values ranged from 40 kJ/m2 to 115 kJ/m2 across different parameter combinations. The optimal settings – layer height of 0.28 mm, nozzle temperature of 215°C and infill density of 30% – achieved a maximum impact strength of 121.23 kJ/m2. This represents a 174% improvement over the base case (44.18 kJ/m2) and a 6% increase over the best non-optimised sample. Among the factors, layer height had the greatest influence (68.8%), followed by infill density (24.4%) and nozzle temperature (6.8%). These findings highlight the value of parameter optimisation in improving the mechanical properties of FFF-printed PLA parts and offer practical guidelines for enhancing their structural performance.
