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Hot Off the Press: 3-D printers making more products—and news

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March/April 2013 Volume 6 Issue 2

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By William Leventon

Contributing Editor

(609) 926-6447

wleventon@verizon.net

Turn on the TV, pick up a consumer magazine or visit a popular Web news portal these days and you just might get an update on 3-D printing—the hottest topic in manufacturing.

In 3-D printing (also known as additive manufacturing), CAD data from computer-created models guides the production of real-world objects. Unlike subtractive techniques, which remove material from a workpiece, additive processes join materials. Normally, this is done by stacking up thin layers of plastics, metals and composites. 3-D printing can produce almost any shape or feature, including those difficult or even impossible to produce by conventional manufacturing processes.

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Skull printed in full color from ordinary business paper on an Mcor IRIS printer. Image courtesy Mcor.

For some time now, the world beyond the technology and manufacturing communities has been interested in 3-D printing. In January, however, it was elevated to weighty national-issue status by no less a figure than President Obama. He mentioned 3-D printing during his second inaugural address, saying it could create high-tech jobs in the U.S., and he called for additional partnerships between public and private entities dedicated to making it more commercially viable.

Such efforts are needed because 3-D printing has yet to reach the status of being a universally accepted manufacturing technology, like molding and machining. Downsides of current 3-D printing techniques include high costs, slow manufacturing speeds, and inferior material properties and surface finishes.

On this front, though, the latest news is good: 3-D printing companies claim to be alleviating some of the technology’s shortcomings. Perhaps equally important, they’re reporting advancements and initiatives aimed at making 3-D printing more accessible to those who could benefit from it.

Following are some recent advancements in the technology.

Paper printing process

When it comes to increasing access to 3-D printing technology, Irish firm Mcor Technologies Ltd. has a very lofty goal. It wants to give everyone access to low-cost 3-D printing.

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EnvisionTEC’s Perfactory Micro offers resolution between 25µm and 35µm, according to the builder. Image courtesy EnvisionTEC.

To that end, the company has introduced a 3-D printer that uses standard letter and office paper as its build material. Called IRIS, the machine turns out parts that cost 95 percent less than those produced by other 3-D printers, according to Mcor.

What’s more, Mcor claims that the color quality of IRIS parts is better than that of the plaster models produced by other 3-D printers, since paper is a better medium for color ink. As a result, “what you see on the [computer] screen is what you get in your hand,” said Conor MacCormack, Mcor’s CEO.

The Mcor system is said to be capable of printing in more than a million colors simultaneously, as well as high-resolution printing on all surfaces, including undercuts and sidewalls. IRIS works in tandem with a standard 2-D color inkjet printer, which prints colors onto a stack of pages, each of which forms a layer of the object being fabricated. Only a thin outline of color is printed on each page, which shows the shape of the object at that particular cross-sectional level. The pages are printed on both sides with Mcor’s patented color ink, which soaks into the page so that white page edges are not visible on the finished object.

Once this process is complete, the stack of pages is fed one at a time into the IRIS. As each page sits on a build plate, a tungsten-carbide blade cuts out the printed shape. A wheel then applies small droplets of a water-based adhesive to the page, with more drops applied to the actual part areas than on the white support material surrounding those areas.

When this process is finished, the user takes the block of paper out of the machine and removes the support material, revealing the part. Because lower adhesive concentrations are used on the supporting material areas, the waste material can be removed by hand or with tweezers. (Part designs must allow for the removal of waste material. So, for example, a hollow sphere couldn’t be created in a single process because the waste material inside couldn’t be removed.) The page areas that make up the part are much stronger since they are bound together by higher adhesive concentrations.

That means parts made by the IRIS can, in addition to serving as models or prototypes, handle more-rigorous duties as well. “People have the misconception that the parts are going to be something like paper mache,” MacCormack said. But thanks to the extra adhesive and the high pressures used to push the stack of paper together, “the objects are actually very solid and durable. They’re almost wood-like structures.”

Among other things, these objects can be used for sand casting, investment casting and vacuum forming. IRIS users also can infiltrate their parts with other materials to make them waterproof or even plastic-like, he added.

Designed to be environmentally friendly, Mcor’s 3-D printing process involves no toxic chemicals or fumes. When they’re no longer needed, objects created by the process can safely be tossed into the recycling bin. As for disadvantages, the process can take hours, and sometimes even a day or longer. Therefore, the IRIS is designed to run unassisted for long periods, MacCormack said.

Desktop system

Another recently introduced system offers high-resolution 3-D printing and a small footprint. Measuring just 9"×8"×24", the Perfactory Micro is billed as “the smallest desktop 3-D printer on the market.”

Made by the German firm EnvisionTEC GmbH, with U.S. headquarters in Dearborn, Mich., Perfactory (short for “Personal Factory”) systems build 3-D objects from liquid resin using a projector similar to those employed in theaters. Featuring Digital Light Processing technology from Texas Instruments, this device projects data for a sequence of volumetric pixels, or voxels, into a liquid photopolymer, causing the resin to cure.

The dimensions of the voxels created by the process can go down to about 15µm in the X, Y and Z directions. Each voxel can take on a different shape, which is determined by the data projected into the resin. According to EnvisionTEC, the voxel-by-voxel building approach can yield products with better surface quality than the layer-by-layer approaches of other 3-D printing technologies.

Like other Perfactory printers, the Micro builds up products in the vertical direction, shining light into a vat of liquid photopolymer to harden all the voxels in one cross-sectional slice of the part. Then it forms the next slice. As the process continues, the part slowly emerges from the vat of resin, attached to the Micro’s build plane.

At the end of the process, the completed part is hanging upside down from the build plane. The process can take from about 1.5 to 5 hours, depending on the height of the part, according to Matt Moser, an EnvisionTEC service and applications technician.

There are different versions of the Perfactory Micro, including those for the dental, hearing aid and jewelry markets. The printer can make parts from a variety of polymers.

Besides having a smaller footprint than competitive products, the Micro is less expensive than other printers offering similar resolution, according to Mary Hoadley, EnvisionTEC’s vice president of global marketing. On the downside, Hoadley noted, the Micro’s small build area puts a fairly low limit on production volumes, so manufacturers would have to step up to a larger machine and/or use multiple machines to meet higher-volume production requirements.

Fast 3-D printing

Like the Mcor and EnvisionTEC systems, older 3-D printers made by the German firm Nanoscribe GmbH take hours to turn out parts. But thanks to a critical design change, Nanoscribe claims to have cut printing times from hours to minutes without reducing the quality of the printed structures.

The design change was made in Nanoscribe’s latest laser lithography system, the Photonic Professional GT. Nanoscribe claims that the GT is the world’s fastest commercially available 3-D printer of micro- and nano-scale structures.

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Polymer structure for cell scaffold research made via Nanoscribe’s laser lithography system. Image courtesy Nanoscribe.

Like its predecessor, the Photonic Professional GT creates tiny 3-D objects using two-photon polymerization, a process in which ultrashort laser pulses polymerize photosensitive material in the laser focus. Successive layers of material are polymerized in this way until the process is completed. Once the unwanted surrounding material is washed away, what’s left is a tiny, self-supporting polymer structure.

The key to the GT’s speed is a galvanometer-controlled mirror system similar to those used in laser light shows and the scanning units of CD and DVD drives. The rotating mirrors laterally deflect laser light, allowing fast and precise positioning of the laser focus.

“Before, we had a fixed laser beam, and the sample was moved in three dimensions with a piezoelectric scanning stage,” explained Martin Hermatschweiler, Nanoscribe’s CEO. “Therefore, heavy masses had to be moved—not just the sample, but also the sample holder, the photoresist and the stage itself—and that slowed down the process. Now, the galvo mirrors move the laser focus in the X and Y directions, and the stage is only used for movement in the Z direction.” The result, Hermatschweiler said, is a hundredfold increase in the speed at which the laser focus is moved—and a dramatic increase in manufacturing speed.

At the highest printing resolution, optical properties limit the scanning field of the GT to a few hundred microns. However, these fields can be “stitched” together like floor tiles to increase the printing area to the desired size.

The GT can make a variety of small objects. These include MEMS devices, micro-optical components, micro- and nano-fluidic structures, and scaffolds for tissue engineering and cell growth studies.

Though the GT has been unveiled, Nanoscribe won’t actually start building the machines until this summer, Hermatschweiler reported. At present, he sees the GT mainly as a tool for research labs rather than mass-manufacturing applications.

Printing tissue

Research labs are also the near-term target of San Diego-based Organovo Inc. Organovo wants to supply labs with products made by its NovoGen MMX bioprinter, which creates functional human tissue from living cells.

The company originally planned to sell the bioprinter, but changed its business model to making tissue for others.

Why? “Commercial-grade life-science tools need to be plug-and-play, push-the-button-and-walk-away kinds of devices,” said Mike Renard, Organovo’s executive vice president of commercial operations. “Today, our printers are not that. They are research-grade devices.”

To make 3-D tissue, the NovoGen deposits layers of a “bio-ink” that consists of living cells. A printhead deposits the bio-ink with positional repeatability down to a few microns, according to Renard. Deposited tubes or droplets of bio-ink have diameters of either 250µm or 500µm.

The machine’s other printhead deposits a hydrogel that serves as a support material for the tissue structure. Layer after layer of bio-ink and hydrogel are deposited until the desired structure has been created. Then, the hydrogel scaffolding dissolves, leaving only the living cells, which fuse together, grow and rearrange themselves to form 3-D tissue.

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Ordinary sheets of business letter paper are drawn into the Mcor IRIS 3D printer. Image courtesy Mcor.

The 3-D tissue can be extremely helpful in various kinds of medical research. In drug testing, for example, it more closely resembles human tissue than the 2-D cell cultures normally used. This can improve the reliability of test results and, thereby, help developers spot drug failures much sooner than usual, saving drug companies considerable time and money.

So far, Organovo has announced partnerships involving the bioprinter with two pharmaceutical companies, Pfizer and United Therapeutics. Recently, the company also announced a collaborative agreement with Oregon Health and Science University, which does early stage drug-discovery work.

To meet the needs of its partners, Organovo is trying to boost its production efficiency and volumes. “If we
wanted to supply live, functional tissues that would last some weeks for drug testing, that would require us to build tissues onto a 24-, 48- or even 96-well microplate,” Renard said. “So our goal would be to efficiently build tissues in those wells that are as identical as cell biology allows.”

Late last year, Organovo also announced that it’s working with CAD company Autodesk Inc. to create what it calls the first 3-D design software for bioprinting. In time, this software may allow users to design their own 3-D tissue, which would then be manufactured by Organovo.

According to Renard, Organovo has experience manufacturing bone, liver, lung, nerve, blood vessel and cardiac tissues. At some point, the company’s
bioprinter also could be used to create organs on demand for transplants, meeting the needs of patients who might otherwise be on a long organ-donor waiting list.

Renard understands the excitement about such a possibility. “People tend to go right to the endgame—building organs.” But, he added, “the reality is that we’re a long, long way from that.”

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The NovoGen MMX Bioprinter is compact enough to fit into a biosafety cabinet. Image courtesy Organovo.

Along the road to printed organs, he sees the bioprinter being used to make “stepping stone tissues,” such as regenerative patches, blood vessels, nerve conduits and urogenital tubes. Production of these simpler structures, he said, is “very plausible given the current state of the technology.”

Technology family

Another 3-D printing firm, the German company microTEC, is now offering to rent or license its family of patented Rapid Micro Product Development (RMPD) technologies for additive manufacturing of 3-D polymer microstructures. RMPD allows tiny components to be made in large or small batches without tooling, according to microTEC.

RMPD processes build 3-D microstructures by depositing thin layers of polymer materials on top of one another. Electronic, mechanical, optical and biological components can be inserted during the process to give parts the desired functionality.

About 80 percent of microTEC’s business involves a process called RMPD-mask, noted company spokesperson Andrea Reinhardt. RMPD-mask is a batch-production technique in which ultraviolet light penetrates a mask to cure many small parts in parallel. With a 14" mask, for example, RMPD-mask can turn out the equivalent of a 1mm3 component every microsecond with micrometer precision, the company claims.

Another process, called RMPD-writing, produces parts with complex 3-D geometries. RMPD-writing uses a laser beam to polymerize UV-curable materials. Splitting a single laser beam allows a number of parts to be produced in parallel.

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A pony figurine produced by microTEC via the RMPD-writing process at the request of a collector. Image courtesy microTEC.

RMPD processes accommodate more than 300 UV-curable materials, including epoxies, acrylics and sol-gels. These photosensitive materials can be made into a variety of products, including microfluidic structures, coil bodies, camera components and internal geared wheels.

The main business of microTEC is providing fabricating services for other companies. But this year the company began offering customers the option of renting its RMPD-mask system. In addition, microTEC will now license its technology to other firms and train them to use it.

“We have customers that are very much interested in using the process at their own site,” Reinhardt explained. µ


Contributors

  • EnvisionTEC Inc.
    (313) 436-4300
    www.envisiontec.com
  • Mcor Technologies Ltd.
    (770) 619-9972
    www.mcortechnologies.com
  • microTEC
    +49 203 306 2050
    www.microtec-d.com
  • Nanoscribe GmbH
    +49 721 60 82 88 40
    www.nanoscribe.de
  • Organovo Inc.
    (858) 550-9994
    www.organovo.com
FtrAuthorAbout

William Leventon is a New Jersey-based freelance writer. He has a M.S. in Engineering from the University of Pennsylvania and a B.S. in Engineering from Temple University. Telephone: (609) 926-6447. E-mail: wleventon@verizon.net. Telephone: (609) 926-6447. E-mail:  wleventon@verizon.net.