RAPID FABRICATION OF MESOSCALE STRUCTURES USING DIGITAL LIGHT PROJECTION-BASED NOZZLE-ASSISTED CONTINUOUS PRINTING

Digital Light Projection (DLP)-based additive manufacturing (AM) has emerged as a powerful tool for fabricating complex three-dimensional (3D) structures with high precision and resolution. However, the current techniques involve challenges related to material availability, design complexity, and manufacturing constraints. Higher viscosity resins, often necessary for better mechanical properties, further complicate the printing process by slowing down resin flow, leading to longer print times. Moreover, the separation force between the cured layer and the build platform can cause defects or incomplete curing during large and solid cross-sectional area printing, limiting scalability. To address these limitations, this work explores the rapid and layerless fabrication technique using a hybrid DLP-based AM process named Nozzle-Assisted Continuous Printing (NCP). Unlike traditional techniques, the proposed method leverages nozzle-based material deposition and continuous solidification to optimize the material refilling and bonding, resulting in faster printing. This paper first presents a novel NCP process and demonstrates the working principle and printing mechanism based on the continuity equation. The effectiveness of the NCP process was validated using various three-dimensional (3D) mesoscale models with solid, hollow, and complex cross-sections. The effect of printing speed on the surface quality and printing accuracy was studied. Compared to the existing layer-by-layer processes, the prepared samples exhibited enhanced surface quality, mechanical strength, and reduction in printing time. As a proof-of-concept application, rapid and precise fabrication of complex three-dimensional (3D) stents for biomedical application was demonstrated. The proposed technique presents a pathway to overcome the limitations of viscosity and cross-sectional constraints while maintaining high speed and part quality. The experimental results demonstrate the potential of the NCP process for applications requiring rapid prototyping and production of detailed mesoscale components with minimal surface defects, including aerospace, biomedical, and mechanical fields.