3D printing is an additive manufacturing process, and the categories of AM and 3D printing encompass the entire process of creating three-dimensional prototypes and structures from digital files. The solid modeling component of computer-aided design is the basis of 3D printing technology. This solid modeling data is used to create extremely thin layers of cross-sectional areas and to fabricate complex shapes and surfaces that are difficult to achieve with conventional methods.
Among them, the STL file format (stereolithography, the abbreviation of stereolithography) is an interface protocol formulated by 3D SYSTEMS in 1988. It is a three-dimensional graphics file format serving rapid prototyping technology. 3D printing has the advantages of less material waste, less post-processing, and very low cost when manufacturing complex parts, making 3D printing a more future-proof technology. 3D printing also has great potential for reusing plastics, recycling, and reducing emissions. The technology is also capable of producing designs with complex geometries, which is also good for products that are lightweight and have a good strength-to-weight ratio. Therefore, 3D printing applications hold great promise in the production of sustainable designs.
1. Fused Deposition Modeling (FDM)
FDM is a thermoplastic polymer, mostly filamentous wire. The thermoplastic filament is heated to the melting point by a nozzle and pushed out layer by layer to form a 3D object. FDM technology was introduced by Stratasys in the United States in the early 1990s by Scott Crump. A 3D printer for FDM consists of a support base that is associated with degrees of freedom and can move up and down in the vertical direction. On the base plate, there is an extruder attached to the wire, which is responsible for heating the wire to the melting point and extruding it layer by layer with the help of a nozzle to form the desired object. The extruder can move in three directions (X, Y, and Z), adjacent layers can be consolidated with each other, and the deposition is done by the extruder. Depending on the desired appearance of the product, the product can eventually be dipped in resin, similar to the SL method. 
picture 1PEEK material printing
picture 2 PLA material printing
2. the first chamber to the second chamber, where fabrication takes place. The powder is heated at a temperature below the melting point, and straighteners or rollers are placed on top of the powder-forming layer. After this manufacturing is complete, finishing is required.
picture 3 Glass fiber nylon(PA12+35% GF)material printing
picture 4 PA12material printing
3. Materials in the 3D printing process
Due to the rapid development of material science, the development of modern 3D printing technology has broken through the limitation of a single raw material. The current innovative materials mainly include hot-melt plastics, light-curing materials, metals, paraffin, etc., which can print multiple complex printing materials at the same time.
4. Development prospect and application of 3D printing
1) The development of 3D printing technology has become an important part of today's social development, and its application fields are also expanding. 3D printing technology is the most widely used in the field of industrial manufacturing. The traditional industrial manufacturing process is gradually replaced. 3D printing technology can quickly manufacture accurate parts, greatly improve manufacturing efficiency, reduce manual operations in the manufacturing process, and reduce costs.
2) 3D printing technology is also widely used in other fields. In the field of energy, equipment modules, embedded sensors, and smart components manufactured by smart components can be made to obtain real-time system performance feedback and on-site monitoring during operation. In the field of construction, 3D printing technology can quickly manufacture various architectural structures, thereby greatly improving construction efficiency. In the field of automobile manufacturing, 3D printing technology can quickly manufacture various auto parts, greatly improve the efficiency of automobile manufacturing, and can also repair automobile engines. The development of 3D printing technology has been paid more and more attention, and the application fields are also expanding.
