One of the first projects with which I was involved when I moved to Michigan in the early 70s was a water recycling system for the home.  (Don’t worry- this had relevance to 3D printing, I promise!) We added a very powerful ultraviolet light (UV) light to disinfect the water. From that UV technology, the ability to “cure” ink on silver aluminum cans was derived.  Which greatly increased the demand for – and technology around- UV curing.

Unbeknownst to us at the time, a guy named Chuck Hull thought of another use for UV lights and UV curing.  He wanted use his UV systems to cure plastics- by having the resin squirt out of the “ink” jets of a printer and be cured in placed by UV.   After all, the UV lights were being used to cure plastic veneer onto tables or tiles; these plasticized objects were used by consumers. Why not use the light to cure the plastic into whatever shape he desired and have each layer become stacked to form a 3 dimensional object.

Which Hull managed to develop.  OK, it wasn’t cheap- his device cost something on the order of a quarter-million dollars or so. But, the first laser printers cost about 500 times what they do now, and that’s the way we expect the cost curves that most technology advances incur.  (Except for healthcare; that is, indeed, the life cycle of technology.)   And, his first units were pretty big- way too big to bring to a customer to let them see how it worked.  So, he used movies- and convinced the automotive industry to use them for prototyping.

And, like the laser printer technology, those 3D printers are now smaller (ok, not that small) and cheaper.  As I’ve mentioned you can buy a 3D printer for less than I paid for my first Spinwriter [a computerized version of the vaunted IBM typewriter of the period] ($1799) in 1982 and my first laser ($1144) printer about 5 years later.

There are slews of 3D printers now that range in price from about $ 800 on up.  But, almost every one of them takes an hour to several hours to complete a “print” a product assembly. Now, Dr. Yong Chen and his group at USC  may be changing that.  Not only can his new printer deal with heterogeneous objects (more than one material or substrate), but the printing process is quick.

The process is based upon MIP-SL (Mask-Image-Projection based StereoLithography), which employs a digital model (of course, three dimensional in nature); the model is sliced into a series of horizontal planes.  These planes are the mask image which is projected onto the photocurable resin (liquid) layer.  The light cures the resin into the desired shape of the layer. But, that’s not enough to speed up the process.  The printer uses two directional motion, enabling the resin to be spread into thin (uniform) layers.  So, the printing is effected in minutes.

This works, even though the substrates cure at different rates.  (Remember, Chen’s process can print heterogeneous objects.)  His group presented a series of papers concerned with his 3D printing advances at the 2013 International Mechanical Engineering Congress and Exposition in San Diego (ASME) in November.

The process I described here was discussed in: An Origami Inspired Additive Manufacturing Process for Building Thin-Shell Structures (IMECE2013-65720) and Modeling and Fabrication of Heterogeneous Three-Dimensional Objects Based on Additive Manufacturing (IMECE2013-65724).

His group also presented another paper describing the 3D printing of concrete structures (I last reported on such efforts in 2011), using Contour Crafting. The goal is to construct structures quickly with polymer-modified concrete (workable and stable in shape); load-bearing capabilities are critical.

Finally, GE has decided that their next generation of jet engines will be made via 3D printing.  Which means these printers will need to be bigger and faster than they are now.  GE will spend $10 to $ 30 million to do this, increase their 3D print staff from 70 to 200 or so, and devote 4X the factory space to these devices.  That’s the only way they’ll be able to produce the 85,000 nozzles they plan to sell in 2015.

So, you can see that the technology of the printers themselves has come a long way- and is about to go much further.  Tomorrow, we’ll talk about the medical applications.

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