Development of an integrated pellet and filament co-extruder system for improved additive manufacturing process

Purpose The purpose of this paper is to develop a versatile extrusion system for solid-based additive manufacturing (AM) that overcomes the limitations of using only filament or pellet extrusion. By combining both in one setup, the study targets enhanced material compatibility, flexible part production and improved printing performance. It addresses the growing need for adaptable AM systems capable of processing polymers in various forms and delivering better print quality, particularly in multi-material and flexible applications. Design/methodology/approach This study introduces a novel multi-material co-extruder system that integrates both pellet and filament extrusion mechanisms into a single setup. The system is designed to process a wide range of industrial polymers – especially those available only in pellet form – enabling flexible, high-quality and multi-material AM. Case studies were conducted to validate the system’s performance in producing flexible parts with improved surface finish and customized material distribution. Findings The developed co-extruder system demonstrated the ability to process both filament and pellet-based materials efficiently. The system enabled high-speed, cost-effective production of flexible and multi-material components with superior surface quality – recording a 19.76% reduction in average surface roughness compared to filament-only prints. In composite (PLA+TPU) parts, the co-extruder achieved intermediate mechanical properties with elongation of 303% and hardness of 71 Shore D (between PLA: 6% elongation, 84 Shore D and TPU: 452% elongation, 52 Shore D). These results confirm the system’s ability to tailor material behavior and minimize staircase effects commonly observed in layer-by-layer AM processes. Originality/value This research presents an original contribution by introducing a dual-mode extrusion system capable of handling both pellet and filament materials within a single AM setup. Unlike conventional systems, this approach facilitates customized material blending and part flexibility, making it suitable for a broader range of applications. The system offers a unique solution for industries requiring material adaptability, high-quality surface finishes and reduced post-processing. Its innovative design also paves the way for more sustainable and cost-effective AM solutions.