Fast Recoating Methods for the Projection-based Stereolithography Process in Micro- and Macro-Scales

The purpose of this paper is to present a recoating method for the development of a direct digital manufacturing (DDM) process that can be an order of magnitude faster than other currently available DDM processes. In the mask-image-projection-based Stereolithography (MIP-SL) process, projection light controlled by a Digital Micromirror Device (DMD) can quickly cure liquid photopolymer resin in a whole area; a fast recoating method is required for achieving truly high-speed fabrication. We investigate the bottom-up projection system in the MIP-SL process. For the macro-scale MIP-SL process, a two-way linear motion approach has been developed for the quick spreading of liquid resin into uniform thin layers. In comparison, a direct pull-up motion can be used in the micro-scale MIP-SL process. The system design and related settings for achieving a fabrication speed of a few seconds per layer are presented. Additionally, the hardware, software, and material setups for fabricating three-dimensional (3D) digital models are presented. Experimental studies using the developed testbed have been performed to verify the effectiveness and efficiency of the presented fast MIP-SL process.