what is 3d printing

In recent years, the term 3D printing has gradually entered people's life and work from unfamiliar to familiar. However, there are still many students who do not know enough about 3D printing. The author writes this article to briefly explain 3D printing technology to our students who are engaged in computer graphics. The purpose of this article is not to explain the concept and application of 3D printing in detail, there are many articles on this topic on the Internet. Our focus is to explain some of the problems and opportunities that 3D printing brings to our researchers engaged in computer graphics and geometric modeling and processing. There are many kinds of 3D printing equipment, and the equipment is designed in conjunction with materials. Here is just a brief list of some common 3D printing equipment (mainly from Medtec), and more detailed information can be obtained from the Internet. 1. Layered solid molding process (LOM): This is the oldest 3D printing molding technology. LOM technology mostly uses paper, PVC film and other materials for forming, which is low in price and high in forming precision. The laser cutter will cut the film along the cross-sectional contour of the workpiece, and the liftable table can support the formed workpiece, and after each layer is formed, it will lower a material thickness to feed a new layer of material to be bonded and cut , and finally the hot-bonded press part will bond the film in the molding area layer by layer. 2. Stereolithography (SLA): Photosensitive resin is used as the material. Under the control of the system, the ultraviolet laser will scan the liquid photosensitive resin to solidify it layer by layer. The liquid tank will be filled with liquid photosensitive resin first, and the ultraviolet laser beam emitted by the helium-cadmium laser or argon ion laser will be scanned line by line and point by point on the surface of the liquid photosensitive resin according to the layered section data of the workpiece under the control of the computer. , which causes the thin layer of resin in the scanned area to polymerize and cure to form a thin layer of the workpiece. 3. Selective laser sintering (SLS): The SLS process uses powdered materials, and the laser scans and irradiates the powder under the control of a computer to achieve sintering and bonding of the materials, so that the materials are piled up layer by layer to achieve molding. First, a layer of powder is spread on the upper surface of the formed workpiece by pressing rollers. The numerical control system controls the laser beam to scan and irradiate the powder layer according to the cross-sectional profile of the layer, so that the temperature of the powder rises to the melting point, so that sintering is carried out. The lower formed part is bonded. 4. Three-dimensional printing process (3DP): The working principle is similar to that of an inkjet printer, and it has similarities with the SLS process. It uses powdered materials, such as ceramics, metals, and plastics, but the difference is that 3DP uses The powder is not bonded together by laser sintering, but the cross-section of the workpiece is 'printed' by spraying the binder through the nozzle and stacked layer by layer. 5. Fused deposition modeling (FDM): heat and melt filamentary hot-melt material (usually ABS or PLA material), extrude the material through an extruder with a fine nozzle, and the molten filament is extruded Immediately after coming out, it will be bonded with the previous layer of material. After a layer of material is deposited, the table will be lowered by a thickness in predetermined increments, and then the above steps will be repeated until the workpiece is fully formed. This is the most common 3D printer, and now the price is only a few thousand yuan, and it is also the 3D printing device that has entered the most homes and personal studios (makers). Also known as a desktop 3D printer.