Imagine a vat of liquid goo. Lasers beams shoot across the pool in seemingly random fashion. Eventually a form – a figurine, part, whatever – rises out of the liquid. You just watched Stereolithography Apparatus (SLA) in action.
SLA is a type of additive manufacturing, also known as 3D printing. It’s called additive because material is added rather than subtracted to make the part or piece. A couple weeks ago we shared a post about Fused Deposition Modeling (FDM). You’ll recall, FDM uses extruded to build layers of material in the shape of your part. If you think FDM videos are cool, wait ‘til you see SLA.
Here’s a great (short) video, courtesy of 3D Systems, that not only breaks down the SLA process, but has great visuals of SLA parts being produced:
The material used in the SLA “printer” is liquid plastic (photopolymer) which hardens quickly. The support structure that forms during the process is easily removed once it comes out of the tank. The part is then cured by UV-light. The end result? SLA creates extremely smooth surfaces, especially when compared to FDM. Most people use SLA for prototyping or making small production runs when they want a near-finished look to the part.
There are pluses and minuses to SLA, of course.
- Aesthetically superior to FDM. Objects have a smooth, trade show finish
- Objects can be finished with paint or even plated (i.e., nickel, chrome)
- Objects can be quite complex.
- Objects are affected by heat and light. They can warp or discolor
- Can be messy
- Limited materials available
That last 'con' — limited materials — could change if researchers at the Karlsruhe Institute of Technology's Institute of Microstructure Technology (IMT) in Karlsruhe, Germany, have anything to say about it. Dr. Bastian Rapp and his team of researchers are working to create SLA objects made of glass, a notoriously difficult material with which to print.
Photo courtesy of Karlsruhe Institute of Technology
According to a recent story in the New York Times, Dr. Rapp's team:
"...Loaded a high concentration of glass nanoparticles into what’s called a photocurable liquid, which hardens under UV light. The mixture sits in a container and is exposed, slice by slice, to UV light that has been programmed to create different shapes at each layer. The regions that are exposed become solid. Heating the structure in a high-temperature furnace, like a ceramics kiln, burns away the leftover liquid and fuses the glass nanoparticles together.
Creating unique or intricate glass shapes this way has the potential to be much easier, and orders of magnitude cheaper, than the methods commonly used today, Dr. Rapp said. Currently, shaping large glass structures involves exhaustive melting and casting processes, and etching fine features involves hazardous chemicals. With this method, you upload your 3-D design, and “the software does all the rest,” he said."
Applications for Dr. Rapp's research are exciting — everything from large architectural pieces to tiny devices for chemistry research, perhaps even high grade optical lenses.
As one of the earliest forms of additive manufacturing, SLA remains highly popular. But as Dr. Rapp's, and other's, research demonstrates, no one is satisfied with the status quo.
Read more about 3D printing and prototyping:
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