In October 2020, a new metal 3D printing technology appeared abroad: solid metal 3D printing deposition technology MELD (similar to friction welding) without melting, which can produce and print metal parts in an open environment.
MELD, a metal 3D printing technology derived from the US Navy, is a solid-state metal 3D printing process. During the printing process, the material can be printed without reaching the melting temperature. It has a wide range of application prospects, including additive manufacturing, coating applications, component repair, metal joining, custom metal alloys and metal matrix composite blanks and parts manufacturing.
What's great is that this metal 3D printing technology can use a variety of materials as raw materials, including metal powder and rods! MELD is a patented additive manufacturing process, based on a process similar to friction welding, which can be used to build and repair metal parts using off-the-shelf solid materials or powders. The process does not involve melting, and can be additively manufactured completely dense parts.
As a solid state process, MELD can produce high-quality materials and parts with lower residual stress and full density, but the energy consumption is much lower than that of traditional processes. Since the printing process of MELDing has always been solid, it will also produce materials that are not susceptible to pores, thermal cracks or other common troubles based on melting technology; a single-step process does not require time-consuming post-processing, such as hot isostatic pressing (HIP) or sintering can improve the quality of deposited materials.
The MELD process can be used for large-scale metal 3D printing parts. Unprecedented scalability, and its huge leap is that, unlike traditional additive manufacturing processes, MELD is not limited to small powder beds or expensive vacuum systems; it is an open process that is not sensitive to the operating environment or material surface conditions; environmental requirements Just like the traditional equipment in the mechanical workshop, such as CNC and rolling mill, it is an ideal choice for real-world industrial manufacturing.
MELD can not only manufacture super large parts, but also very fast. The speed of depositing materials is at least 10 times faster than the 3D printing process based on molten metal, and there are very few material restrictions, from aluminum, titanium, steel to nickel-based super alloys. The same machines and the same processes can be used to manufacture high-quality materials.
The MELD process "stimulates" plastically deformed or softened metals together or into the underlying layer. This friction stirring effect destroys the individual crystal grains that make up the metal. Therefore, the "fine" particle size of the products printed by MELD is or smaller than the matrix material used. In metals, as the grain size becomes smaller, it can generally have higher strength. Higher corrosion resistance and higher wear resistance. The smaller grain size is one of the reasons for the better mechanical properties.
Inconel 625 is a nickel-based super alloy.
Before the MELD process, the average grain size is 12 microns; after the MELD, the average grain size is 5 microns, and the strength is higher. The material deposited by MELD not only looks great, but also has excellent mechanical properties that meet or exceed the original material. This means that the "fusion" material will exhibit the expected performance, thus breaking the limit. Whether it is aluminum, titanium or nickel-based super alloys, MELD machines can deposit high-quality materials in one step.