Constrained Window Design in Projection Stereolithography for Continuous Three-Dimensional Printing

Although continuous projection Stereolithography (SL) printing is one of the next-generation ultra-fast additive manufacturing (AM) processes, its current constrained window design of the resin vat is suffering from many challenges, such as the complex control mechanism and limited hardware lifetime. In this article, we investigate a novel constrained window design, namely Island Window (IW), for the continuous three-dimensional (3D) printing by using the projection SL process. The proposed IW window has a highly oxygen-permeable polydimethylsiloxane membrane onto the laser-machined acrylic vat frame, which allows the formation of an effective liquid interface (>200 μm oxygen inhibition layer) to enable the continuous projection SL process. Experimental results verified the feasibility of the window design for extending the maximum printing time (increased by up to 73%) due to the enhanced oxygen concentration. It was also found that the maximum printing speed for producing parts with a smooth surface (Rz <30 μm) can be as high as 90 mm/h, which is comparable to the speeds in recently reported continuous SL processes. In addition, a variety of parts were successfully fabricated through continuous 3D printing by using the proposed IW design, implying tremendous promise for future low-cost, high-resolution, easy-controlled, and ultra-fast AM processes.