University of Wisconsin-Madison engineers have found a approach to concurrently mitigate three varieties of defects in parts produced using a outstanding additive manufacturing technique called laser powder bed fusion.
Led by Lianyi Chen, an associate professor of mechanical engineering at UW-Madison, the team discovered the mechanisms and identified the processing conditions that may result in this significant reduction in defects. The researchers detailed their findings in a paper published on November 16, 2024, within the International Journal of Machine Tools and Manufacture.
“Previous research has normally focused on reducing one sort of defect, but that may require the usage of other techniques to mitigate the remaining varieties of defects,” Chen says. “Based on the mechanisms we discovered, we developed an approach that may mitigate all of the defects — pores, rough surfaces and huge spatters — without delay. As well as, our approach allows us to provide a component much faster with none quality compromises.”
Multiple industries, including aerospace, medical and energy, are increasingly enthusiastic about using additive manufacturing, also often called 3D printing, to provide metal parts with complex shapes which might be difficult or unattainable to create using conventional methods.
But the large challenge is that metal parts created with additive manufacturing have defects — like pores, or “voids,” rough surfaces and huge spatters — that significantly compromise the finished part’s reliability and sturdiness. These quality problems prevent 3D-printed parts from getting used for critical applications where failure shouldn’t be an option.
By providing a path for concurrently increasing part quality and manufacturing productivity, the UW-Madison team’s advance may lead to widespread industry adoption of laser powder bed fusion.
Laser powder bed fusion uses a high-energy laser beam to melt and fuse thin layers of metal powder, constructing a component layer by layer from the underside up. On this research, the UW-Madison team used an revolutionary ring-shaped laser beam, provided by a number one laser company called nLight, as an alternative of the standard Gaussian-shaped beam.
The ring-shaped laser beam played a key role on this breakthrough — as did critical “in-situ” experiments, says Jiandong Yuan, the lead creator of the paper and a PhD student in Chen’s group.
To see how the fabric behaved throughout the part because it was printing, researchers went to the Advanced Photon Source, an ultra-bright, high-energy synchrotron X-ray user facility at Argonne National Laboratory. Combining high-speed synchrotron X-ray imaging, theoretical evaluation and numerical simulation, the researchers revealed the defect mitigation mechanisms, which involve phenomena that reduce instabilities within the laser powder bed fusion process.
The researchers also demonstrated that they may use the ring-shaped beam to drill deeper into the fabric without causing instabilities in the method. This enabled them to print thicker layers, increasing the manufacturing productivity. “Because we understood the underlying mechanisms, we could more quickly discover the correct processing conditions to provide high-quality parts using the ring-shaped beam,” says Chen.
Lianyi Chen is the Kuo K. & Cindy F. Wang Associate Professor of mechanical engineering.
Collaborators from UW-Madison include Qilin Guo, Luis Escano, Ali Nabba, Minglei Qu, Junye Huang, Qingyuan Li, Allen Jonathan Román, and Professor Tim Osswald. Samuel Clark and Kamel Fezzaa from Argonne National Laboratory also collaborated on this project.
This work was supported by the National Science Foundation and the Wisconsin Alumni Research Foundation.
