Using a continuous liquid interface production (CLIP) polymerization process, Carbon3D (Redwood City, CA), which is working with researchers at the University of North Carolina (Chapel Hill, NC) and North Carolina State University (Raleigh, NC), can fabricate 3D-printed objects tens of centimeters in size with 100 μm resolution in minutes (500 mm/hour rates possible), as opposed to the hours required for stepwise layer-by-layer photopolymerization methods used in conventional 3D printing.
Unlike traditional bottom-up stereolithography printers whereby ultraviolet (UV) light exposure, resin renewal, and part movement are conducted in separate, discrete steps, the CLIP process projects a continuous sequence of images in UV light generated through a digital light-processing unit onto an oxygen-permeable, UV-transparent window below a liquid resin bath. An oxygen-containing dead zone inhibits photopolymerization above the window and maintains a liquid interface below the advancing part. As the curing part is drawn out of the resin, suction forces constantly renew reactive liquid resin that cures to form the object. This dead zone is maintained by adjusting the photon flux rate of the source, the concentration of photoinitiator in the resin, and the resin curing dosage, determined by the reactivity of the resin. Carbon3D is able to apply the entire polymer chemistry textbook and make parts that range from hard prototyping and engineering resins to elastomers, completely biodegradable materials, and materials that would be useful for casting of metal. Reference: J. R. Tumbleston et al., Science, 1349–1352 (Mar. 20, 2015); http://dx.doi.org/10.1126/science.aaa2397.