Jan 31, 2018 | By Benedict
The Department of Energy’s SLAC National Accelerator Laboratory is investigating how to avoid flaws in metal 3D printed parts. Its X-ray observation processes could result in more reliable 3D printed parts.
Whether your 3D printer is set up at home, in a factory, on a ship, or even in space, you always want your 3D printed objects to have as few flaws as possible, whether that’s for aesthetic purposes or for ensuring the functionality of a critical part. Sometimes, however, it can be difficult to identify the causes of flaws: is it something to do with the 3D printing material or the 3D printer itself? Perhaps the flaw comes from the CAD 3D model used to build the part?
Scientists at the Department of Energy’s SLAC National Accelerator Laboratory are just as curious about why flaws occur in 3D printed parts—metal 3D printed parts, especially—so they’re using an observation rig equipped with an X-ray in order to better understand what makes 3D prints go wrong. The scientists think the research could benefit manufacturers of all kinds of 3D printed items, in sectors like aerospace, automotive, and healthcare.
The research is being carried out at the laboratory’s Stanford Synchrotron Radiation Lightsource (SSRL), and is being helped along by scientists from the DOE’s Lawrence Livermore National Laboratory and Ames Laboratory. Together, these scientists are using two X-ray methods to see what happens during the process of metal 3D printing—an incredibly useful technology, but one that is yet to be perfected.
“With 3D printing, you can make parts with very complex geometries that are not accessible for casting like regular metal parts,” said SLAC staff scientist and project leader Johanna Nelson Weker. “Theoretically, it can be a quick turnaround: simply design, send, print from a remote location. But we’re not there yet. We still need to figure out all of the parameters involved in making solid, strong parts.”
Readers are probably well aware of the various flaws that can occur with plastic-extruding fused deposition modeling (FDM) 3D printers, but metal 3D printers present their own sets of problems. During selective laser melting (SLM), for example, the powder-melting laser beam process often produces pits or weak spots when the metal cools and hardens unevenly while building up the layers. But why do they occur, and how can they be avoided?
During these studies, the SLAC scientists are trying to get to the bottom of this big additive manufacturing problem, analyzing the kind of metal used, the level of heat from the laser, the speed at which the metal heats and cools, and other factors that could be contributing to the flaws in the 3D printed parts.
“We are providing the fundamental physics research that will help us identify which aspects of metal 3D printing are important,” commented Chris Tassone, a staff scientist in SSRL’s Materials Science Division.
The scientists believe that the use of X-rays rather than thermal imaging devices can uncover the secrets of pit formation. They’re using two different X-ray techniques, one that captures micron-resolution images of what happens as the layers of metal build up, and another that bounces X-rays off the atoms in the material to analyze its atomic structure as it melts and then cools.
The researchers—Nelson Weker, Tassone, and four others: Kevin Stone, Anthony Fong, Andrew Kiss, and Vivek Thampy—are far from getting any definitive answers yet, but are confident that their new X-ray setup could dramatically improve metal 3D printing, should the causes of pits and weak spots eventually be identified. The study will also be used to observe other kinds of metal additive manufacturing, including directed energy deposition.
As the study moves forward, the scientists also plan to introduce other observational tools into the process, including a high-speed camera that can collect photographs and video footage of the manufacturing process. They will then be able to match their images with their X-ray data at certain points in order to obtain a fuller understanding of what is going on in the metal 3D printed parts.
“We want people to be able to connect what they see on their cameras with what we are measuring here so they can infer what’s happening below the surface of the growing metal material,” explained Nelson Weker. “We want to put meaning to those signatures.”
For the entire industry’s sake, we hope they find what they’re looking for.
Posted in 3D Printing Technology
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