Carbon‘s Continuous Liquid Interface Production (CLIP) 3D printed parts are put to the test. Design for Additive Manfuacturing (DfAM) training is explored at ETH Zürich. The National Institute of Standards and Technology (NIST) examines the effect of defects on the surface of 3D printed components. And Lawrence Livermore National Laboratory (LLNL) researchers investigate the potential of laser peening for post-processing.
3D Printing Industry reviews the most recent literature in additive manufacturing.
CLIP 3D printed lattices undergo mechanical testing
A study conducted by researchers at the University of Illinois at Urbana-Champaign, puts the mechanical properties of Carbon’s CLIP 3D printed lattices to the test.
In the course of the study, over 50 CLIP 3D printed parts were tested using proprietary Carbon materials: additive epoxy (EPX), rigid polyurethane (RPU), cyanate ester (CE), and flexible polyurethane (FPU).
Results showed that, “The measured elastic moduli of the printed structures are close to the values expected from the material vendor’s specifications, although there is some variation; this variation is different for different materials.”
CE, RPU, and FPU at relative densities of 0.06, 0.12, 0.12, and 0.23 respectively. The ruler shows millimeters.” Photo via University of Illinois at Urbana-Champaign
All values are fully explored in a paper presented at the IUTAM Symposium Architectured Materials Mechanics in Chicago, available online via Purdue University. David McGregor, Sameh Tawfick and William King are credited as the paper’s co-authors.
Inner defects revealed on the surface of 3D printed parts
At the 2018 ASPE and euspen Summer Topical Meeting in California, NIST scientists presented the findings of a paper exploring the relationship between the surface topology of 3D printed components and their subsurface defects.
According the research abstract “Additive manufactured (AM) components exhibit an abundance of surface textures and patterns. Past work investigating components created through laser powder bed fusion (LPBF) has shown that these patterns, specifically the chevron resulting from solidification of the melt pool on upward facing surfaces, can be correlated to quality of the final part.”
By comparing scans of the surface of a 3D printed nickel component to x-ray computed tomography (XCT) of the same object, the researchers make a case for using the approach for in-situ detection of flaws.
“Effect of Subsurface Defects on the Surface Topography of Additive Manufactured Components” is available open-access via NIST’s government website. Is it co-authored by Zachary C. Reese, Jason C. Fox, Felix H. Kim, John Taylor and Christopher Evans.
Addressing the additive manufacturing skills shortage
Addressing engineering’s additive manufacturing skills shortage, a team at ETH Zürich have studied the outcomes of a course created to teach DfAM skills to mechanical engineering graduates.
The curriculum was developed based on the Experience Transfer Model (ETM), an educational technique dependent on human conduct, learning or performance on prior experience.
The course covered concept, design, data preparation, and post-processing for FDM, SLS and SLM through lectures and a practical project. According to feedback, the majority of students felt positively about the outcomes of the course.
In a second semester, the ETH research leaders encourage candidates to apply for the course by submitting their own ideas for an AM project “in order to further increase the intrinsic motivation of the teams.”
“Enabling Graduate Students to Design for Additive Manufacturing through Teaching and Experience Transfer” is published online in ETH’s Research Collection. It is co-authored by Julian Ferchow, Christoph Klahn and Mirko Meboldt.
Laser peening for post-processing
LLNL, in collaboration with New Jersey metal finishing specialist Curtiss Wright Surface Technologies, are exploring shot and laser peening as a potential post-processing method to improve the qualities of 3D printed parts.
According to the team’s most recent findings, laser peening “is clearly shown to provide superior fatigue life and strength” in sample 3D printed parts. Additionally, the ability to shape and/or correctively reshape AM components is explored with this method.
“Laser Peening: A Tool for Additive Manufacturing Post-processing” is published in Additive Manufacturing journal. It is co-authored by Lloyd Hackel, Jon R. Rankin, Alexander Rubenchik, Wayne E. King, Manyalibo “Libo” Matthews.
Libo Matthews and other LLNL researchers also recently published a paper relating to a machine learning model for in-situ defect detection in 3D printing.
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Featured image shows Carbon’s Continuous Liquid Interface Production (CLIP) 3D printing in action. Screengrab via Carbon on YouTube
