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D-Shape
D-Shape is a large 3-dimensional printer that uses binder-jetting, a layer-by-layer printing process, to bind sand with an inorganic seawater[1] and magnesium-based binder[2] in order to create stone-like objects. Invented by Enrico Dini, founder of Monolite UK Ltd, the first model of the D-Shape printer used epoxy resin, commonly used as an adhesive in the construction of skis, cars, and airplanes, as a binder. Dini patented this model in 2006.[3] After experiencing problems with the epoxy, Dini changed the binder to the current magnesium-based one and patented the printer again in September 2008.[4] In the future Dini aims to use the printer to create full-scale buildings. Technical descriptionThe current version of the D-Shape 3-D printer sits in a 6 m by 6 m aluminium frame. The frame consists of a square base that moves upwards along four vertical beams during the printing process via stepper motors, which are used to repeatedly move a specified length and then hold in place, on each beam. Spanning the entire horizontal 6 m of the base is a printer head with 300 nozzles, each spaced 20 mm apart. The printer head is connected to the base by an aluminium beam that runs perpendicular to the printer head.[5] ProcessBefore the actual printing process can begin, a 3-D model of the object to be printed must be created on CAD, a software that allows a designer to create 3-D models on a computer. Once the model is finished, the CAD file is sent to the printer head. The printing process begins when a layer of sand from 5 to 10 mm thick, mixed with solid magnesium oxide (MgO),[6] is evenly distributed by the printer head in the area enclosed by the frame. The printer head breaks the 3-D model into 2-D slices. Then, starting with the bottom slice, the head moves across the base and deposits an inorganic binding liquid made up of a solution that includes magnesium chloride, at a resolution of 25 DPI (1.0 mm).[7] The binder and sand chemically react to form a sandstone material. It takes about 24 hours for the material to completely solidify. The material resembles, by composition, the Sorel cement. The 20 mm gap between the nozzles may require filling. An electric piston on the beam holding the printer head shifts the head in a direction perpendicular to the printer’s motion to fill these gaps and provide consistent exposure of the sand to the binder. D-Shape completes each layer with four forward and backward strokes. Stepper motors on the vertical beams adjust the base upwards after a layer is completed. The hollow framework above the printer head is refilled cyclically, distributing new sand into the frame to form the next layer. [8] During the printing process, excess sand supports the solidifying material and can be reused for subsequent printings. The process continues uninterrupted until the desired structure is fully printed. After the printer finishes its work, the final structure must be extruded from the sand. Workers use shovels to take out the excess sand and reveal the final product. The magnesium oxide mixed in with the sand causes the sand to become an active participant in the reaction, resulting in a mineral-like material with a microcrystalline structure. Compared to concrete, which has low resistance to tension and as a result needs iron reinforcement, D-Shape's structures have relatively high tension resistance and do not need iron reinforcement.[9] The entire building process is reported to take a quarter of the time and a third to a half of the cost[10] of building the same structure with traditional means using portland cement, the material currently used in building construction.[11] Awards and achievementsNYC Waterfront Construction CompetitionIn the fall of 2012, D-Shape entered into the NYC Waterfront Construction Competition hosted by the New York City Economic Development Corporation (NYCEDC) in which competitors had to create an innovative solution to help strengthen New York City's deteriorating piers and coastline structures. D-Shape's idea, called, "Digital Concrete," was to take 3-D scans of each piece of pier or infrastructure, and then print a support jacket for each specific piece. D-Shape was the First Place Winner and received $50,000 for the idea, which is estimated to save New York City $2.9 billion.[12][13] RadiolariaD-Shape successfully created the tallest 3-D printed sculpture, Radiolaria, in 2009.[14] The sculpture was created by Italian architect Andrea Morgante and inspired by radiolarians, unicellular organisms with intricate mineral skeletons. The current version of the sculpture is only a 3 x 3 x 3 m scale model of the full-size Radiolaria that is planned to be put in a roundabout in Pontedera, Italy.[15] Future of D-ShapeCurrently, Jake Wake-Walker and Marc Webb are working on a documentary titled The Man Who Prints Houses, about Enrico Dini and his invention.[16] Although D-Shape has garnered attention for its printing abilities, it is still in development. It has gotten close to printing an actual house by printing a Trullo, a small, stone hut,[17] but the printer still needs to be modified in order to make printing larger and more complex buildings a reality. Lunar bases Because of D-Shape's capabilities, the European Space Agency (ESA) has taken interest in using the printer to build Moon bases.[18] The ESA is interested in using D-Shape to build Moon bases out of lunar regolith, otherwise known as Moon dust, because the 3-D printer can build the base onsite without human intervention. This is advantageous because only the machine would have to be taken to the Moon, thus reducing the cost of bringing building materials to the lunar surface to create the bases. D-Shape has been successful in printing components for the lunar bases with a simulated Moon dust, and has also been subject to tests that aim to see how the printer will work in the environment on the Moon.[19] References
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