In ‘Fabrication and measurement of 3D printed retroflective fibers,’ authors Michael Ghebrebrhan, Gabriel Z. J. Loke, and Yoel Fink are engaged in studying novel materials for additive manufacturing processes. With a new retroreflective fiber, the authors offer a material combination with a previously unheard of complex (non-circular, non-convex) cross-section that also exhibits optical scattering properties. This new kind of fiber is built up layer by layer but can subsequently be used as a fiber would.
As thermal drawing becomes more popular again for creating complex fibers, researchers make use of polymers, metals, elastomers, and more. For this research project, they created a 3D printed preform meant to retroreflect light—or as the authors explain, ‘the angle of reflection is the negative of the angle of incidence.’ The preform is made of polymer and metal (polycarbonate (PC) and indium), with the fiber acting as the element that retroreflects light.
“Glass beads on a reflective surface are a familiar example of a retroreflective surface,” state the researchers. “To maximize retroreflectivity, the polymer’s refractive index should be close to 1.9. At that index, a cylinder or sphere will refract light towards the intersection of the optical axis and back surface.”
The preforms were 3D printed on a Stratasys Fortus 450MC printer, with infill at the highest setting as attempts to increase it otherwise failed; the issue with indium is that it is so much more dense than PC, and the preform must be able to resist deformation.
“Hence a print path that traces multiple concentric paths should be used to counteract the outward hydrostatic pressure from the liquid indium for preserving the cross-section and preventing pooling (lumping) of indium in the draw furnace,” state the researchers.
As the researchers worked to stop pooling of indium, they lowered dwell time and maximum temperature as much as possible. They did, however, find that because the preform is 3D printed, strength was not as high as in comparison to a solid rod. Because of that, its viscosity had to be lower than a solid preform—created with a preform that includes a ‘long solid bottom.’
One part of a fiber with five filled channels was then taken for retroreflection. As light was focused on the fiber, the team recorded intensity with a spectrometer.
“As our figure of merit, we calculate the amount of light retroreflected by a single fiber relative to that of a white reflecting standard. Both are then scaled by the intercepted area. This yields a rescaled relative retroreflection ratio (RRR),” concluded the researchers. “Across the visible spectrum we obtain a rescaled RRR of roughly 260.
“Complex cross-section preforms are easily attainable with additive manufacturing and future efforts will explore the addition of multiple materials.”
The study of materials continues to become more complex in 3D printing, and especially with composites—from continuous fiber to wire polymers, flax biocomposite, and countless others. What do you think of this news? Let us know your thoughts! Join the discussion of this and other 3D printing topics at 3DPrintBoard.com.[Source / Images: ‘Fabrication and measurement of 3D printed retroflective fibers’]
Subscribe to Our Email Newsletter
Stay up-to-date on all the latest news from the 3D printing industry and receive information and offers from third party vendors.
You May Also Like
Daring AM: Why Is Relativity Space’s 3D Printed Rocket Still Grounded?
Launching the world’s first 3D printed rocket was not going to be so easy. So, when Relativity Space announced that it’s 85% additively manufactured Terran 1 launch vehicle was ready...
Relativity Space’s 3D Printed Rocket Launch Called Off
Relativity Space’s highly awaited blast of its 3D printed rocket was scrubbed. An issue with the temperature of the propellants on the rocket’s second stage meant the launch was called...
Norsk 3D Prints Titanium Parts for Semiconductor Market
Norsk Titanium, a metal additive manufacturing (AM) company based in Norway, announced that the company has made its first commercial delivery of parts for the semiconductor market. Using its patented...
The Future of Directed Energy Deposition is Unbounded
“Well, that depends…” I said. “On what?” he said. “It depends on what you want out of the process,” I emphasized. “All I want is a finished metal part just...
Upload your 3D Models and get them printed quickly and efficiently.