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Choi, Jae-Won,Wicker, Ryan B.,Cho, Seok-Hyun,Ha, Chang-Sik,Lee, Seok-Hee Emerald Group Publishing Limited 2009 RAPID PROTOTYPING JOURNAL Vol.15 No.1
<B>Purpose</B> - The paper's aim is to explore a method using light absorption for improving manufacturing of complex, three-dimensional (3D) micro-parts with a previously developed dynamic mask projection microstereolithography (MSL) system. A common issue with stereolithography systems and especially important in MSL is uncontrolled penetration of the ultraviolet light source into the photocrosslinkable resin when fabricating down-facing surfaces. To accurately fabricate complex 3D parts with down-facing surfaces, a chemical light absorber, Tinuvin 327™ was mixed in different concentrations into an acrylate-based photocurable resin, and the solutions were tested for cure depths and successful micro-part fabrication. <B>Design/methodology/approach</B> - Tinuvin 327 was selected as the light absorber based on its high absorption characteristics (~0.4) at 365?nm (the filtered light wavelength used in the MSL system). Four concentrations of Tinuvin 327 in resin were used (0.00, 0.05, 0.10, and 0.15 percent (w/w)), and cure depth experiments were performed. To investigate the effects of different concentrations of Tinuvin 327 on complex 3D microstructure fabrication, several microstructures with overhanging features such as a fan and spring were fabricated. <B>Findings</B> - Results showed that higher concentrations of Tinuvin 327 reduced penetration depths and thus cure depths. For the resin with 0.15 percent (w/w) of the Tinuvin 327, a cure depth of ~30?µm was achieved as compared to ~200?µm without the light absorber. The four resin solutions were used to fabricate complex 3D microstructures, and different concentrations of Tinuvin 327 at a given irradiance and exposure energy were required for successful fabrication depending on the geometry of the micro-part (concentrations of 0.05 and 0.1 percent (w/w) provided the most accurate builds for the fan and spring, respectively). <B>Research limitations/implications</B> - Although two different concentrations of light absorber in solution were required to demonstrate successful fabrication for two different micro-part geometries (a fan and spring), the experiments were performed using a single irradiance and exposure energy. A single solution with the light absorber could have possibly been used to fabricate these micro-parts by varying irradiance and/or exposure energy, although the effects of varying these parameters on geometric accuracy, mechanical strength, overall manufacturing time, and other variables were not explored. <B>Originality/value</B> - This work systematically investigated 3D microstructure fabrication using different concentrations of a light absorber in solution, and demonstrated that different light absorption characteristics were required for different down-facing micro-features.
클라우드 기반 3D 프린팅 활용 생산 시스템 통합 연구
김지언,David Espaline,Eric MacDonald,Ryan B. Wicker,김다혜,성지현,이재욱 한국기계가공학회 2015 한국기계가공학회지 Vol.14 No.3
After the US government declared 3D printing technology a next-generation manufacturing technology, there have been many practical studies conducted to expand 3D printing technology to manufacturing technologies, called AMERICA MAKES. In particular, the Keck Center, located at the University of Texas at El Paso, has studied techniques for easily combing the 3D stacking process with space mobility and expanded these techniques to simultaneous staking techniques for multiple materials. Additionally, it developed convergence manufacturing techniques, such as direct inking techniques, in order to produce a module structure that combines electronic circuits and components, such as CUBESET. However, in these studies, it is impossible to develop a unified system using traditional independent through simple sequencing connections. This is because there are many problems in the integration between the stacking modeling of 3D printers and post-machining, such as thermal deformations, the precision accuracy of 3D printers, and independently driven coordinate problems among process systems. Therefore, in this paper, the integration method is suggested, which combines these 3D printers and subsequent machining process systems through an Internet-based cloud. Additionally, the sequential integrated system of a 3D printer, an NC milling machine, machine vision, and direct inking are realized.