What Is Additive Manufacturing?

Additive Manufacturing (AM), commonly known as 3D printing, combines computer-aided design, material processing and molding technology, and uses digital model files as the basis. Software and CNC systems are used to convert special metal materials, non-metal materials, and medical biological materials , According to extrusion, sintering, melting, light curing, spraying, etc., layer by layer, manufacturing solid article manufacturing technology. Compared with the traditional processing mode of removing, cutting, and assembling raw materials, it is a "bottom-up" manufacturing method that accumulates materials from scratch. This makes it impossible to manufacture complex structural parts that were restricted by traditional manufacturing methods in the past.

Additive manufacturing

Academician Guanqiao proposed the concepts of "broad sense" and "narrow sense" of additive manufacturing (as shown in the figure). "Narrow sense" of additive manufacturing refers to the technology of combining different energy sources with CAD / CAM technology and accumulating materials in layers. System; and "broad sense" additive manufacturing is a large-scale technology group with the accumulation of materials as its basic characteristics and the direct manufacture of parts as its goal. If classified according to the type and method of processing materials, it can be further divided into metal forming, non-metal forming, biomaterial forming, etc. (as shown).

The first is the control technology of the material unit. That is, how to control the physical and chemical changes of the material unit during the stacking process is a difficult point. For example, in the direct metal forming, the size of the micro-melting pool of laser melting and the external atmosphere control directly affect the manufacturing accuracy and the performance of the part.
The second is equipment recoating technology. Additive manufacturing automated coating is a necessary process for material accumulation, and the process of recoating directly determines the accuracy and quality of the part in the accumulation direction. The layer thickness is developed to 0.01mm. Controlling the smaller layer thickness and its stability is the key to improve the precision of the part and reduce the surface roughness.
The third is efficient manufacturing technology. Additive manufacturing is developing towards large-size component manufacturing technology. For example, metal laser directly manufactures titanium alloy frame cymbals on aircraft. Frame cymbals are up to 6m in length and the production time is too long. How to achieve simultaneous laser beam manufacturing and improve Manufacturing efficiency, ensuring the consistency between synchronous additive organizations and the quality of manufacturing combined areas are difficult points for development.
In addition, in order to improve efficiency, the combination of additive manufacturing and traditional cutting manufacturing, and the development of composite manufacturing technology of material accumulation manufacturing and material removal manufacturing are also the development direction and key technology.

AM technology does not require traditional tools and fixtures and multiple processing procedures. It can quickly and accurately manufacture parts of any complex shape on a single device, thereby achieving "free manufacturing" of parts and solving the formation of many complex structural parts. And greatly reduce the processing procedures and shorten the processing cycle. And the more complex the product structure, the more significant its effect on manufacturing speed.

3D printing technology is becoming an important carrier for developed countries to realize the return of manufacturing industry and improve industrial competitiveness. It can be said that the new round of global manufacturing competition is most likely the competition between 3D printing and high-end equipment such as robots. Digitalization, intelligent manufacturing and the application of new materials represented by 3D printing will reshape the relationship between manufacturing and service industries, reshape the comparative advantages of countries and regions, reshape the pattern of economic development, and accelerate the process of the third industrial revolution.

As a developing manufacturing technology, the maturity of additive manufacturing is far from being comparable to manufacturing technologies such as metal cutting, casting, forging, welding, and powder metallurgy. There is still a lot of research work to be done, including special alloys for laser forming. The system, the organization and performance control of parts, the control of stress and deformation, the detection and control of defects, and the development of advanced equipment, etc., involve research at all levels, from scientific foundations, engineering applications to industrial production quality assurance.
China's insufficient investment in the research and development and application of new equipment for additive manufacturing technology lags behind foreign countries in many aspects. Compared to the US and European countries, we have fallen behind in the development of new technologies, such as the lack of research and development in 3D color printing technology. In terms of application, many of our industries lack follow-up technology research and development, for example, no system technology system has been formed in the transformation of rapid manufacturing prototypes to molds and functional parts, and companies have not applied this technology well in product development.
Additive manufacturing is particularly suitable for the small batch production of parts and components in aerospace products, and has the advantages of low cost and high efficiency. This reflects the rapid and economic advantages of additive manufacturing on complex curved surfaces and structural manufacturing. Foreign rapid prototyping technology has more than 8% of the application in the aviation field, while China's application is very low.
In China, some 3D printing equipment manufacturing companies are independent, and some universities and research institutes that research related technologies are also independent. This loose industry relationship makes the rapid development of domestic rapid prototyping technology difficult, and it is difficult to compare with foreign technology. contend. To this end, experts suggest that government departments and industries pay close attention to the development of new technologies and give policy support. In addition to industrial policies and financial support, we hope to form an industry alliance.
Experts suggest that relevant national government departments take the lead in setting up close organizations such as industry associations or technology alliances, integrate domestic related resources, give full play to the respective advantages of scientific research units and manufacturing companies, and make up for each other's weaknesses, truly making domestic additive manufacturing technology Catch up with foreign countries, the level of manufacturing of 3D printing equipment has been improved, 3D printing entrepreneurial bases have been established, 3D printing centers have been established, 3D printing industry clusters have been developed, and China's additive manufacturing technology has developed rapidly to lead the manufacturing industry to accelerate its transformation and upgrading.