Manufacturing Bits: Feb. 19

Computed Axial Lithography; dichroic cups.


Computed Axial Lithography
Lawrence Livermore National Laboratory (LLNL) and the University of California at Berkeley have developed a 3D printing method to produce a new class of polymer parts.

The technology, called Computed Axial Lithography (CAL), projects photons on a resin in a vial within a 3D printer. In total, researchers have demonstrated the ability to shine 1,440 different projections with four beams into the resin.

The photons illuminate the resin as the vial rotates. This in turn creates shifting videos of projections as the vial rotates. Eventually, the process forms 3D objects in the resin. The process takes several minutes to complete. This is faster than existing polymer 3D printing techniques.

With the technology, researchers have devised a small airplane model, lattice structures and a miniaturized version of Rodin’s famous sculpture “The Thinker.” In the future, the technology could enable sports equipment, footwear, clothing and hearing aids.

“This is a breakthrough in the space of possible methods to do additive manufacturing,” said LLNL engineer Maxim Shusteff. “What this approach does is make it possible for interesting polymer parts to be made much more quickly, which is often a bottleneck, and we can now think about using materials that don’t work well with slower layer-by-layer methods.”

Chris Spadaccini, director of LLNL’s Center for Engineered Materials and Manufacturing, added: “This method is more powerful than other VAM (volumetric multibeam printing) concepts because it can create more complex structures in a layer-less fashion while using standard projection technology. It’s layer-less, it produces parts with good surface roughness, it is fast and we believe it to be scalable to much larger sizes.”

Dichroic cups
Wageningen University has developed a 3D printing technology that enables objects with the so-called dichroic effect.

The dichroic effect involves a glass. The glass displays different colors, depending on the lighting conditions. One example is the Lycurgus Cup, a 4th-century Roman glass cage cup. It is a dichroic cup. It displays different colors, which depends on the angle of light.

The dichroic effect is achieved by using nanoparticles of gold and silver. Even the Roman Empire developed dichroic cups using nanoparticles. The process used by the Romans is still a mystery.

Nonetheless, researchers from Wageningen have developed a way to synthesize gold nanoparticles. The amount of gold is roughly 0.07% weight. Then, using these particles, researchers can devise dichroic cups using a standard 3D printer. This in turn opens the door for new forms of art. It could also one day lead to nanocomposite-based lenses and filters.

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