The first equipment and materials were developed in the eighties. 1981 Hideo Kodama of Nagoya Industrial Research Institute invented two AM methods for making a three-dimensional plastic model with a photo-curing polymer. After curing, this photo polymer hardens in the light and thus a plastic model is created. Exposure of this polymer to rays, light, was controlled with the help of a mask. In 1984, Chuck Hull developed a prototype based on this process known as stereolithography – the hardening of plastic resin under the influence of light. Hal patented this technique a few years later and founded 3D Systems, among other things thanks to Kodama, who did not patent his invention in time.
Hull defines this process as: «A system for generating three-dimensional objects by creating a cross-sectional pattern of the object being formed», but this was previously invented by Kodama. Hal’s contribution is the design of the STL (Stereolithography) format widely accepted by 3D printing software. His contribution is also the digital cutting and filling strategy, common to many processes today.
During these years, other technologies and processes of 3D printing appear, but the simplest method is layering. The printer ejects the molten plastic onto the work surface, layer by layer. The plastic cools down and these layers merge. The printer creates a specific object from the bottom, moving quickly to the top with each new layer.
In January 2009, the first commercially available 3D printer based on the RepRap concept appeared. The RepRap project is an initiative to develop a 3D printer that can print most of its own parts. RepRap (short for replicating rapid prototyper) uses a variant of depositional fusion modeling, an additive manufacturing technology. As an open design, all printer types produced by the project are released under a free software license, the GNU General Public License.
To date, the RepRap project has released four 3D printing machines: «Darwin,» released in March 2007, «Mendel,» released in October 2009, «Prussia Mendel,» and «Huxley,» released in 2010. The authors named them after famous biologists since «the purpose of RepRap is replication and evolution». Because of the machine’s self-replicating capabilities, the authors envision the possibility of cheaply shipping RepRap units to people, allowing them to create (or download from the Internet) complex products, without the need for expensive industrial infrastructure, including scientific equipment. Their intention for the RepRap is to show the evolution in this process.
At the heart of RepRap is a thermoplastic extruder. Early RepRap extruders used a geared DC motor that drove a screw that pressed firmly on the plastic fiber, forcing it through a heated melt chamber and narrow extruder nozzle. However, because of their high inertia, DC motors cannot start or stop quickly, and therefore were difficult to control precisely. Therefore, newer extruders use stepper motors (sometimes geared) to move the fiber, pressing the fiber between the toothed shaft and the bearing.
Almost any 3D modeling program or CAD can be used with RepRap, as long as it is capable of producing STL files. Authors use tools they are familiar with, whether they are commercial CAD programs like SolidWorks or open source 3D modeling programs like Blender or OpenSCAD. RepRaps can print objects from ABS, polylactic acid, and similar thermopolymers.
If we take into account the materials used for 3D printing, we can say that they became diverse. An increasing number of metals are used especially for industrial 3D printing. One of the strongest and most commonly used metals is stainless steel, which is used in the form of powder, using the sintering technique, combining the powder into solid objects. The sintering technique uses various powdered materials from metal to ceramics. Powder fusion is performed under the influence of a laser, but electron beams or a focused heat source are also used. Stainless steel gives a natural silver color, but it can be coated with other materials to give a bronze or gold effect. In the last few years, both gold and silver have been used as materials that can be printed directly. They are used in the jewelry industry as well.
Ceramics are a relatively new group of materials used for 3D printing with varying degrees of success. 3D printed paper models are economical, safe, easy to recycle and do not require any post process. Wood, Styrofoam, plasticine are also used as materials. There is a lot of research into the potential of 3D printing with bio-materials. Bioprinting involves taking cells and possibly multiplying them outside the body and making replacement organs. It is believed that if the cell for reproduction is taken from the person who will be the recipient, the body will more easily accept such an organ. This part already really feels like science fiction with the ideas of immortality and printing the organs we need.
Experimentation with food printing has become more frequent in the last few years. There are printers that work with sugar, paste and meat. Probably everyone dreams of printing chocolate or a complete meal.
Below, we embark on a journey through time to revisit the major milestones that have paved the path for 3D printing in architecture, arousing it to its current status and unlocking the doors to a bright future.
