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Metal 3-D printing has enormous potential to revolutionize modern manufacturing. However, the most popular metal printing processes, which use lasers to fuse together fine metal powder, have their limitations. Parts produced using selective laser melting (SLM) and other powder-based metal techniques often end up with gaps or defects caused by a variety of factors.
To overcome the drawbacks of SLM, Lawrence Livermore National Laboratory researchers, along with collaborators at Worchester[sic] Polytechnic Institute , are taking a wholly new approach to metal 3-D printing with a process they call direct metal writing, in which semisolid metal is directly extruded from a nozzle. The metal is engineered to be a shear thinning material, which means it acts like a solid when standing still, but flows like a liquid when a force is applied.
[...]Instead of starting with metal powder, the direct metal writing technique uses an ingot that is heated until it reaches a semi-solid state—solid metal particles are surrounded by a liquid metal, resulting in a paste-like behavior, then it's forced through a nozzle. The material is shear thinning because, when it's at rest, the solid metal particles clump up and cause the structure to be solid. As soon at the material moves, or is in shear, the solid particles break up and the system acts like the liquid matrix. It hardens as it cools, so there's less incorporated oxide and less residual stress in the part, the researchers explained.
[...]"The main issue was getting very tight control over the flow," said LLNL engineer Andy Pascall. "You need precise control of the temperature. How you stir it, how fast you stir it, all makes a difference. If you can get the flow properties right, then you really have something. What we've done is really understand the way the material is flowing through the nozzle. Now we've gotten such good control that we can print self-supporting structures. That's never been done before."
More information: Wen Chen et al. Direct metal writing: Controlling the rheology through microstructure, Applied Physics Letters (2017). DOI: 10.1063/1.4977555
(Score: 1, Interesting) by Anonymous Coward on Monday April 03 2017, @12:05AM (1 child)
http://vadersystems.com/ [vadersystems.com]
No Star Wars connection, Vader is actually the family name of this father/son company. Here is a newspaper article about them,
http://buffalonews.com/2017/02/22/amherst-father-son-team-bursting-ideas-one-bloomed-high-tech-startup/ [buffalonews.com]
The claim is a much cheaper process because it starts with aluminum wire (as used for welding, very low cost) instead of very expensive finely ground and graded aluminum powder. It probably will never be capable of the level of detail that can be done with the laser sintering process but there is probably a place in the market for cheap and fast (the usual, pick any two of good, cheap, fast).
(Score: 2) by lx on Monday April 03 2017, @07:26AM
Slightly disappointed that mr. Vader didn't name his son "Luke"