A fused granule fabrication system utilizing thermoplastic powder for improved mechanical ductility

Filament-based fused deposition modeling suffers from high cost and limited feedstock, while existing screw-based material extrusion (MEX) systems are primarily designed for granular or pellet feedstocks. Therefore, this study presents the design, development and experimental validation of a novel MEX system, capable of direct processing of thermoplastic powder materials. The system comprises a rigid frame, a screw-based extrusion unit, a precision movement system, and a heated build platform. Using this system, the printing parameters for powder-based fabrication were systematically optimized via single-factor experimental method. Polylactic acid (PLA) tensile specimens were produced using both the developed powder-based system (designated as PLAP) and a commercial filament-based FDM printer (PLAF) for benchmark comparison. While the PLAP specimens exhibited moderately lower yield strength (43.11–49.35 MPa) compared to PLAF, they demonstrated an enhanced ductile mechanical performance. The fracture strain of PLAP samples ranged from 8.31 % to 9.22 %, representing a substantial 15–27 % increase over their filament-based counterparts. This marked enhancement in ductility highlights a key advantage of the proposed powder-based process, suggesting its strong potential for applications requiring superior toughness and performance under impact or cyclic loading conditions, thereby offering a cost-effective and material-efficient alternative to conventional filament-based FDM.