Metal 3D printing has existed only for about half of the 3D printing industry’s 30-year-long history and as impressive as the technology is, it remains expensive and complex. A new breed of metal 3D printer manufacturers hope to bring down its cost and difficulty.
These companies which include Markforged, Desktop Metal and Admatec leverage the older technique of metal injection molding to create metal parts that can then be sintered in an oven to achieve final part characteristics. While Desktop Metal has received the most attention, due to the $97 million in funding it has received from companies like Google, GE and BMW, it is just one startup in what may become a larger trend for less expensive metal 3D printing.
To learn about Admatec’s digital light processing (DLP) approach to metal 3D printing, as well as ceramic 3D printing, ENGINEERING.com reached out to the company’s managing director, Michiel de Bruijcker. De Bruijcker was able to tell us about the company’s unique technology, shedding light on how it may fit into the developing additive manufacturing (AM) landscape.
From Injection Molding to 3D Printing
De Bruijcker explained that Admatec has its roots in powder metallurgy for ceramics and metal injection molding as a spin off of another Dutch company, Formatec Ceramics. Founded in 1996, Formatec focuses specifically on ceramic injection molding.
As illustrated in the video above, the process is similar to polymer injection molding, in that a metal mold is filled with material to produce an end part. With ceramics, however, a slurry made of ceramic particles and a binder material, is injected into the mold. The resulting “green” part is placed into a furnace, which burns out the binder and sinters the ceramic together.
According to de Bruijcker, when he became managing director at Formatec in 2011, he and his team began exploring methods for shaping metal and ceramic powders, such as extrusion. The team wondered whether or not it was possible to form shapes with 3D printing, before debinding and sintering. With funds from Formatec, his team began research towards that end.
Using DLP, it was possible to load a photosensitive resin with ceramic powder and 3D print it. Thanks to Formatec’s years of experience with debinding and sintering, this process was not a difficult one. The R&D work started in the summer of 2012, and by November 2013, a new company, Admatec, was born.
Unlike other DLP processes, which project light from below onto a vat of photosensitive resin, Admatec’s technology uses a foil to carry the material above a UV projector and below a suspended printbed. The printbed then descends onto the foil, at which point the projector casts its light and cures the resin onto the printbed. This process is continued until the print is complete and the part is placed into an oven to be debound and sintered to above 99.7 percent density. “[W]e had a prototype machine and then we constructed four printers,” de Bruijcker said. “Those four printers were just used internally to serve as a chop shop. So, a job [at Formatec] would come to us, we would print them the files and hand over to product. That was our initial business model. At the same time, patents were being issued and granted for our technology. Then, we had enough flying hours on these homemade machines to say that we felt secure enough about the technology. We felt secure enough to go fully into the market.”
3D Printing Ceramics and Metals
In May 2016, Admatec unveiled the ADMAFLEX 130, a 3D printer capable of 3D printing ceramics. Priced competitively, the ADMAFLEX 130 can print with zirconium oxide, aluminium oxide and fused silica materials. Though the company has these materials on the market, the system will not be limited to them.
In fact, the ADMAFLEX machine is open in terms of materials, meaning that customers, such as those at research universities and applied research institutes, can concoct their own slurries. “We strongly believe that the market is so young that it is actually better to go to market with more people doing development work than by us alone,” de Bruijcker explained.
Of the relevant applications for the technology, de Bruijcker said, “It’s surprising how many applications are actually out there specifically meant for 3D printing. It can be used for high tech components where high temperatures are required. We are strong in taking on developments for bone implants, which will take a little bit longer to realize. Dental is a big one. We are printing cores for investment casting in the rotor and blade market for aviation. The technology is used for printing aesthetic items, for instance for the eyewear industry. We are printing for the microreactor market, to perform reactions related to the separation of fuels. Every 6 months there’s another application.”
Translating the technology over to metals required some extensive work with the Energy Research Centre of the Netherlands, but at AMUG 2017, Admatec unveiled the ADMETALFLEX metal 3D printer. One of the biggest issues associated with DLP metal 3D printing was creating the proper slurry. Due to the darker nature of metal powders, the particles would absorb far more light, and do so far more quickly, than the ceramics.
“We had to fix that issue in order to have the light travel through the photosensitive resin and actually activate and crosslink the polymers,” de Bruijcker said. “We had to coat the metal powder in order to do that effectively.”
Additionally, the suction forces between the slurry and the printbed are higher in the metal system. Admatec had to develop some specific engineering solutions to handle those higher forces. The ADMETALFLEX is also able to print at finer resolutions than the ADMAFLEX 130.
Like its ceramic predecessor, the ADMETALFLEX will have an open materials platform. Currently, it can print with 316L stainless steel and Admatec is developing tungsten, Inconel and titanium.
The Advantages of DLP
Though Markforged and Desktop Metal are introducing metal 3D printers to the market that rely on similar MIM technologies, ADMATEC has a unique advantage. DLP 3D printing is famous for its high resolution, and the ADMETALFLEX can print with details as fine as 0.3 to 0.4mm.
“There are a couple of advantages of this technology,” de Bruijcker explained. “One of them is that you’re completely disconnecting the shaping process and the material properties. The shaping is done by a DLP printing system, but the material properties are coming from the sintering oven, which gives you a very nice, homogenous warm oven which you are able to get better material properties than you would get from a [selective laser melting] machine.”
In addition to the fine detail, the surface finish is also quite smooth, according to de Bruijcker. This is not the case with selective laser melting technologies for metal 3D printing. Those parts require significant post-processing to get them to the point that they can be displayed on the trade show floor. It may be that, with the launch of Desktop Metal and Markforged’s technologies, Admatec has come onto the market at the right time. Very high profile U.S. companies are showing the world that metal 3D printing can be much more affordable than previously thought via indirect MIM-style methods. It’s even possible that customers would buy machines from multiple manufacturers, as an ADMETALFLEX system could be used for highly detailed parts and another company’s product for another application.
And Desktop Metal, Markforged and Admatec won’t be alone in the market. Israel’s XJet has its own inkjet-based metal 3D printing process, for instance. And once the manufacturing industry recognizes the affordability of indirect metal printing processes, ExOne may be able to pick up more customers as well. HP has also demonstrated that its multi jet fusion platform can be modified to 3D print ceramics. If that’s the case, it wouldn’t be surprising if the company unveiled metal 3D-printed parts at an upcoming event. Who knows? Maybe other DLP manufacturers, like Carbon, will develop their own metal-loaded photosensitive resins.
In the meantime, Admatec is working on its own technology. “We have a very keen interest in obviously widening our material portfolio,” de Bruijcker said. “We would also like to increase the building envelope without losing resolution.” The ADMAFLEX 130 is already available for ordering, while the ADMETALFLEX will ship in Q3 of this year. To learn more about the company and its products, visit the Admatec website.