Metal 3D printing has enormous potential to revolutionize modern manufacturing. However, the existing metal 3D printing processes, which use lasers to fuse together fine metal powder, have their limitations. The reason being that metals generally don't exist in a state that they can be readily extruded. Therefore this approach is often costly and complicated and requires unwieldy support structures that are not distorted by the high temperatures of the fabrication process. Thanksfully, researchers from Yale University working with a company called Desktop Metals think they’ve found a way to make 3D printing metal objects easier than ever before. Researchers demonstrated a new approach to 3D printing to fuse metallic filaments made from metallic glass into metallic objects.
A sample part printed from bulk metallic glass via the TPF-based FFF process. Credit: © 2018 The Authors. Published by Elsevier.
"We have shown theoretically in this work that we can use a range of other bulk metallic glasses and are working on making the process more practical- and commercially-usable to make 3D printing of metals as easy and practical as the 3D printing of thermoplastics," said Jan Schroers, Professor of Mechanical Engineering and Materials Science at Yale University.
Unlike conventional metals, bulk metallic glasses (BMGs) have a super-cooled liquid region in their thermodynamic profile and are able to undergo continuous softening upon heating -- a phenomenon that is present in thermoplastics, but not conventional metals. This means BMGs can soften more easily than most other metals, and can be used in 3D printing to generate solid, high-strength metal components.
Prof. Schroers and colleagues simplifies the additive manufacturing of metallic components by exploiting the unique-amongst-metals softening behavior of BMGs. Paired with this plastic like characteristics are high strength and elastic limits, high fracture toughness, and high corrosion resistance. The team has focused on a well-characterized and readily available BMG made from zirconium, titanium, copper, nickel and beryllium, with alloy formula: Zr44Ti11Cu10Ni10Be25.
The team used amorphous rods of 1 millimeter (mm) diameter and of 700mm length. An extrusion temperate of 460 degrees Celsius is used and an extrusion force of 10 to 1,000 Newtons to force the softened fibers through a 0.5mm diameter nozzle. The fibers are then extruded into a 400°C stainless steel mesh wherein crystallization does not occur until at least a day has passed, before a robotically controlled extrusion can be carried out to create the desired object.
In order to make BMG 3D printing a wide-spread technique, researchers say that the raw materials they used should be made more widely available. Due to the similarity between FFF of thermoplastics and BMGs, this method may leverage the technology infrastructure built by the thermoplastic FFF community as many of the engineering challenges that have been solved in thermoplastic FFF can be readily translated to the printing of BMGs. As a consequence, this research could help rapidly realize and proliferate accessible and practical printing of metals.
Their research was just published in the journal Materials Science.
Posted in 3D Printing Technology