Since the advent of 3D printing technology, 3D printing technology has been gradually applied to the manufacture of actual products. Among them, the development of 3D printing technology for metal materials is particularly rapid. In the field of national defense, developed countries in Europe and the United States attach great importance to the development of metal 3D printing technology and invest huge sums of money in research. 3D printing metal parts has always been the focus of research and application. Not only can it print molds and bicycles, it can also print unprecedented new weapons, and it can even print large equipment such as cars and airplanes. As a new type of intelligent manufacturing technology, metal 3D printing has shown a very broad application prospect, and has shown a strong development momentum in more fields such as equipment design and manufacturing, equipment support, and aerospace.
1 Overview of metal 3D printing technology
1.1 Basic overview
The core idea of metal 3D printing technology first originated in the United States at the end of the 19th century, but it did not take shape until the mid-1980s. In 1986, American Charles Hull invented the first 3D printer. my country began to study 3D printing technology in 1991. Around 2000, these processes began to gradually develop from laboratory research to engineering and productization. At that time it was called rapid prototyping (RP), that is, mock-ups before samples were developed. Now there is also called rapid prototyping technology, additive manufacturing. However, for the convenience of public acceptance, this new technology is collectively referred to as 3D printing. 3D printing is a kind of rapid prototyping technology. It is a technology based on digital model design, using bondable materials such as powdered metal or resin, and constructing three-dimensional objects by "additive" printing layer by layer. Metal 3D printing has been called "the thought and technology of the last century, the market of this century". Moreover, my country has recently made a breakthrough in metal 3D printing aerospace. China's aerospace has made a new breakthrough, and the weight of 3D printed metal parts has been reduced from 3kg to 600g, a weight reduction of 80%.
1.2 Features of metal 3D printing
1) High precision. At present, the accuracy of metal 3D printing equipment can basically be controlled below 0.05mm.
2) The cycle is short. Metal 3D printing does not require the production process of molds, which greatly shortens the production time of the model. Generally, a model can be printed in a few hours or even tens of minutes.
3) It can be personalized. Metal 3D printing has no limit to the number of printed models, no matter one or more can be produced at the same cost.
4) Diversity of materials. A metal 3D printing system can often realize the printing of different materials, and the diversity of this material can meet the needs of different fields.
5) The cost is relatively low. Although metal 3D printing systems and metal materials for 3D printing are relatively expensive now, if they are used to make personalized products, the production cost is relatively low.
Selective Laser Melting (SLM)
SLM is an important part of the field of metal 3D printing. Its development history has gone through stages such as sintering of low melting point non-metallic powder, sintering of low melting point coated high melting point powder, and direct melting of high melting point powder. The University of Texas at Austin first applied for a patent in 1986, and successfully developed the first SLM equipment in 1988. It uses a finely focused spot to quickly melt into a preset powder material of 30-51 μm, and can almost directly obtain any shape. As well as functional parts with complete metallurgical bonding. The density can reach nearly 100%, the dimensional accuracy can reach 20-50 μm, and the surface roughness can reach 20-30 μm. It is a rapid prototyping technology with great development prospects.
SLM molding materials are mostly single-component metal powders, including austenitic stainless steel, nickel-based alloys, titanium-based alloys, cobalt-chromium alloys, and precious metals. The laser beam quickly melts the metal powder and obtains a continuous melting channel, which can directly obtain nearly dense metal parts with almost any shape, complete metallurgical bonding, and high precision. It is a 3D printing technology for metal parts with great development prospects. Its application range has been extended to aerospace, microelectronics, medical treatment, jewelry, and other industries.
There are more than 50 influencing factors in the SLM process, and there are six categories that have an important impact on the molding effect: material properties, laser, and optical path systems, scanning features, molding atmosphere, molding geometric features, and equipment factors. At present, researchers at home and abroad mainly conduct process research and application research on the above-mentioned influencing factors, with the purpose of solving defects in the molding process and improving the quality of molded parts. In terms of process research, the important process parameters in the SLM forming process include laser power, scanning speed, powder layer thickness, scanning distance, scanning strategy, etc. By combining different process parameters, the forming quality can be optimized.
JR has been engaged in 3D printing for more than 10 years, please feel free to contact us to learn more about our metal 3D printing.