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The future is now
When 3D printers first came out, they were a sensation, but still a bit of a novelty. They did not have much practical use. That changed very quickly. The materials got, and continue to get, better, stronger and more varied.
Figure 1 A miniature version of the statue “The Thinker,” created using the new 3D-printing system (Credit: Stephen McNally, UC Berkeley)
Since its inception, there have been two types of additive printing. The first is FDM or fused deposition modeling. This is very much like dot matrix printing but in 3D. You take a small blob of something and adhere it to previously deposited blobs. On a piece of paper, the blobs are ink. In many 3D printers, those blobs are melted thermoplastic, a type of plastic that can be melted and re-solidified. The product comes in rolls of material called filament. Not only is this done on table top models, but forward-thinking individuals now use cement and robotically controlled dispensing nozzles to build houses and other structures.
The other broad category of printers is SLA or stereo lithography. In the early days, two or more laser beams were used to convert the polymers in a liquid bath into a solid. The lasers were at right angles and while the intensity was too low for either of them to cause the polymerization, at the point where they crossed, there was sufficient energy to initiate the reaction.
Today there are at least 10 different types of 3D printing technologies. The materials are varied and growing all the time. But recently, 2017, researchers at UC Berkley and Lawrence Livermore National Laboratory, have taken a leap forward.
In conventional 3D printing, a form of deposition printing, a body is built up a layer at a time. In FDM you start at the bottom and build up. In SLA you start at the top and build down. FDM is done in air and SLA is done in a bath. What Hayden Taylor, Assistant Professor of Mechanical Engineering at UC Berkeley, and his team have done is completely different. They form the entire image at the same time. Rather than constructing it layer by layer, it is constructed all at once. In figure 1, you can see a model of the thinker that they produced in just a few minutes. If you have done any 3D printing, I need to say that again. The entire model was made in just a few minutes, not in hours.
The vat of resin is rotated and the image projected into it, through it. As the vat is rotated, the presented image is altered. The molecules in the resin absorb energy from the light. When sufficient energy is absorbed, the gelatin polymerizes.
This process is like the revers of a CT scan technology. In a CT scan you use an x-ray beam to measure a 3-D object. In their process they look at what type of beam you would need to project to create a 3D object. In both cases, the beams will pass completely though the object that is either being created or scanned.
The resin is called Gelatin Methacrylate Hydrogel and it is made of three key components: Liquid polymers, photo initiators and oxygen. The oxygen must be consumed before the solidification can occur. The light that causes the reaction is projected through the entire fluid. It is possible to have the reaction go wrong and a fuzzy blob in the center is all you get. You will notice that the resulting model does not have the high resolution and crisp edges know for processes like SLA. This is technology is in its infancy, but it has the potential to dramatically change the world of 3D printing.
Sean O’Leary is sometimes known as the Celtic Engineer. He was involved in putting two missions on the space shuttle. He has worked at the Smelter’s Biproducts department of Kennecott Utah Copper. Has helped design ballistic guidance systems for Northrop Grumman. Worked on various DARPA projects, an anti-RPG system known as Iron-Curtain and has been involved with the downhole oil and gas industry. He currently is the owner of Celtic Engineering Solutions a consulting Engineering Company in West Jordan and Murray Utah.
3D printers have been used to form organs and other non-ridged models. One of the things this new process, called Computer Axial Lithography or CAT, can do is called over molding. You can, for example, print the handle on a screwdriver directly onto the shaft. It will be interesting to see how creative minds use this new technology to improve our world. Personally, I look forward to the day I can walk up to a wall monitor and ask for “Tea. Earl Gray. 60 degrees C.” Don’t you?
At Celtic Engineering Solutions we are constantly looking for new and innovative ways to help our customers succeed. Give us a call today so we can talk about how we might help you with your project.
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