Metal 3D Printing: Laser Melting And Jetting Technology-advantages And Limitations

- Jan 20, 2021-

Metal 3D printing is moving from laboratory-level applications to factory-level production applications. There is also a certain degree of competition among various technologies of metal 3D printing. In this issue, 3D Science Valley and Gu You come to appreciate the characteristics and limitations of the popular powder bed metal melting technology and the binder jetting metal 3D printing technology that is popular with investors.       Frontal competition or dislocation competition    Compared with other direct metal 3D printing technologies, metal powder bed melting is currently a widely used metal 3D printing technology. Including General Electric's US$1.4 billion acquisition of Concept Laser and Arcam last year, which further strengthened the market's focus on metal powder bed melting. PBF is considered to be a direct metal 3D printing technology, including two processing methods: laser melting and electron beam melting. At present, laser melting is more widely used. In this field, many brands are active, including Concept Laser and Arcam acquired by GE, including the original metal 3D printing solution provider EOS of Germany, SLM Solutions of Germany, Renishaw of the UK, domestic Blite, Beijing Longyuan, Yi Add three-dimensional, Xin Jinghe and the traditional machine tool manufacturers that have entered the PBF field, Germany's TRUMPF, and DMG Mori Precision.    However, from the investment market, a large amount of investment funds have poured into another metal 3D printing method due to high speed, high volume and low cost, which is usually considered indirect metal 3D printing. Indirect metal 3D printing technology, so the name implies that the metal parts obtained through the metal 3D printing process are not final parts, but need to remove the chemical substances in the metal parts through the heat treatment process of the high-temperature furnace to obtain dense Metal parts. Of course, the current indirect metal 3D printing technology includes a variety of different technologies. According to the market research of 3D Science Valley, one category is the binder jetting technology represented by Exone, Desktop Metal, 3DEO, and Markforged, and the other category is represented by Xjet. The third category of NanoParticle Jetting technology is the metal 3D printing technology developed by Prodways and CEA Tech LITEN with resin as the indirect body, and the fourth category may be classified as the metal 3D printing technology to be launched by HP.   PBF technology   
When the laser melting process starts, a layer of metal powder is laid on the build tray, and then the metal powder is melted layer by layer through the energy source. Due to the realization of very complex product manufacturing, PBF technology not only makes the manufacture of complex products more feasible, but also creates greater comprehensive economic benefits.    For example, when manufacturing cost-effective and complex molds through PBF technology, such as conformal cooling of the mold. How to efficiently cool plastic products in a small cycle time has become a key consideration in the design and manufacturing process of conformal cooling molds. The conformal cooling of additive manufacturing greatly optimizes the cooling effect, increases the life of the mold, and improves the final Quality of products. In this regard, Shanghai Yue Rui 3D has accumulated a wealth of 3D printing conformal cooling mold design and manufacturing experience.   
For another example, GE has continuously optimized, tested, and re-optimized its fuel injector design through more than 10 years of exploration, reducing the number of fuel injector parts by one from more than 20. In terms of comprehensive benefits, the additive manufacturing method not only improves the problem of easy overheating and carbon deposition of the fuel injector, but also increases the service life of the fuel injector by 5 times, and will improve the performance of the LEAP engine.    And Airbus's bionic structure cabin has also subverted the traditional production method and mechanical properties of the cabin. This serial production of parts called Scalmalloy not only plays an important role in reducing the waste of titanium metal, but also saves a lot of fuel consumption for the aircraft by reducing weight.    However, from laboratory-level applications to production, the limitations of PBF have also emerged. For example, the melting temperature of stainless steel can be close to 2500 degrees Fahrenheit. Imagine the processing of parts when each individual 3D printing equipment needs to continuously consume energy. The overall energy consumption cannot be underestimated. Unless, the comprehensive benefits created by PBF technology are so obvious in the above-mentioned classic cases. Therefore, in the field of mass production, such high costs usually only make sense when processing special parts that are difficult to process by traditional methods, including those with extremely complicated internal passages, as well as jet engine fuel nozzles and satellite components. And other high-end components.    In addition to energy consumption, PBF technology is also subject to material restrictions and processable size restrictions, material prices, process control, and the need to add support structures. These factors have become the reasons that restrict the popularization of PBF technology. Of course, with the improvement of technology and the improvement of quality control capabilities through software, PBF technology is constantly breaking through its own limitations.  
 Material injection + sintering    The indirect metal 3D printing technology adopted by Exone, 3DEO, Markforged and Desktop Metal is based on the combination of material injection and sintering processes to produce metal parts with full density. Lower-cost equipment also means that the cost of parts is greatly reduced, and large-volume parts with lower costs are a key element for production.    The current limitation of 3D printing of metal parts by binder jetting is the size of the parts. Early binder injection techniques used bronze penetration to reduce the associated shrinkage and sintering problems, but this changed the material properties of the metal and did not prove to be a viable solution for producing parts. However, newer adhesive spraying technology equipment will be launched soon, hoping to solve the problem of structural size, while obtaining the advantages of low-cost parts and high production.   
3DEO's intelligent layering technology is a molding method that combines traditional manufacturing techniques with new additive manufacturing technology. CNC machining is used in the machining process to achieve more geometric contours. What kind of competition will direct metal 3D printing technology and indirect metal 3D printing technology form in the future? This is a topic worthy of consideration and continued attention. In the 3D Science Valley, there is a possibility that PBF laser melting technology will focus on The manufacturing of high value-added parts and the creation of finer material crystal structures; while the bulk indirect metal manufacturing technology such as binder jetting has the advantages of high volume and low cost to meet the market demand not covered by PBF laser melting technology. Of course, this is also a peaceful situation, and experience tells us that competition is often not so good.