Key Techniques Research On Slm 3D Printing Equipment For Dental Application

3D printing is regarded as the principal force of the third industrial revolution. It is the ideal way of digital manufacture, because 3D printing is able to print final product directly just based on 3D digital model. The process step, from design to manufacturing, was sharply reduced. The traditional manufacturing processes are subtractive manufacturing. But 3D printing is additive manufacturing. It can reduce the material waste. 3D printing is rapid, customized and green manufacturing, has been widely applied in developed countries, for the research and development of military weapons, space devices, medical instruments, and many other high-end areas. Nevertheless, China’s 3D printing technology development is in an early period of development. In 2015, China’s state council formally issued the "made in China 2025", to promote development of manufacturing. As an emerging technology, 3D printing occupies important position in it. In the medical application, 3D printing has attracted more attention because it features rapid and customized. In 2015, medical(mostly dental medical) share 13.1% of the 3D printing marketing. Most of value is created by metal crowns, bridge, denture and implants, etc. they are built by 3D printing based on selective laser melting(SLM) technology. So dental is the most important direction of SLM 3D printing industry. But many valuable parts of SLM, such as software, equipment, materials and other key technology are dominated by just a few foreign companies. Equipment is the foundation to study 3D printing material, process, and software. Foreign equipment usually bundle software, material and process, to erect technical barriers. The focus of this article, is combined with the actual demand of dental health, studies the key technology of dental SLM, finally, designes and developes SLM equipment.In this paper, dental SLM application was researched firstly. SLM process is from digital model to the laser scanning path plan, and then to the final melting and forming. According to this process, CAD data source, data slicing algorithm, the process of laser and material, oxygen content control, high precision and fast correction of scanning galvanometer, scanning graphical interface were researched. Among them, the study of data source and data slicing algorithm are foundation of laser scanning path plan. The study of laser and material process is the precondition of laser optical design and oxygen content control research. And laser scanning and forming depend on high precision and fast correction of scanning galvanometer. In this paper, based on the study of above key problems, the structure of SLM equipment was designed. And laser transmission system with adjustable laser beam size, powder bed lifting system, forming chamber, powder feeding system were present. Finally, the dental SLM equipment was developed. Its processing range can be up to 250 mm * 250 mm, and max building height is 200 mm. In the end of this paper, SLM forming experiment was introduced. SLM builds were test for physical and chemical properties, and biological compatibility. The test result was present is this paper.The following are main innovative achievement of this paper: 1) The dental SLM 3D printing requirement was researched. The special SLM equipment was designed for the requirement. 2) A fast galvanometer system correction algorithm based on image recognition was present. It is an effective correction solution for large size SLM building process. 3) The visualization programming of stereo lithography interface specification(STL) file was built. A rapid slice algorithm was designed and implemented without establishing the topological relationship. And a rapid algorithm for sorting slice intersected lines in end to end was designed and implemented. To verify these algorithms, a kind of stereolithography plotter(SLP) equipment was present, which is expected to become a new type of 3D printing. SLP was drove by synchronous belt rather than scanner galvanometer. So it reduces demand of laser power. 4) SLM forming chamber model was built. The optimizing method based on computational fluid method was present. The final optimized chamber structure was established, which has balance flow density and homogeneous flow velocity in it. Oxygen content can be reduced quickly in this chamber. 5) A complete system of SLM electronic, mechanical and software solutions were implemented. It has open graphical interface, adjustable focused laser beam size. More research about algorithm, control and material can be executed on this system in the future.