DLP 3D Printing Does Metal with Prodways
Michael Molitch-Hou posted on October 04, 2016 |

It’s no secret that metal 3D printing is becoming big business. Just ask GE Aviation, which just purchased two of the leading metal 3D printing companies in the industry. As the technology becomes integrated into the mainstream manufacturing supply chain, other 3D printing firms are going to have to keep pace with this rapidly evolving industry.

Prodways, the 3D printing subsidiary of the French Groupe Gorgé, is making its own advancements in the space by developing a new metal 3D printing material using the company’s existing technology. Developed with the Alternative Energies and Atomic Energy Commission (CEA), a French public research organization, this process expands on Prodways’ already expanding technology portfolio, which includes selective laser sintering (SLS) and rapid digital light processing (DLP) for metal casting.

In an exclusive scoop for ENGINEERING.com, Alban D’Halluin, managing director of Prodways, was able to discuss the implications of this new material technique, as well as the French firm’s other unique 3D printing technologies.

3D Printing with Metal Paste

The R&D group at Prodways has spent two years working with CEATech LITEN, a subsidiary of CEA, to create a novel metal 3D printing technique that fuses metal powder with an organic binder. Prodways’ existing V6000 machine applies the firm’s existing MOVINGLight technology to viscous pastes. Up until now, the V6000 has been used to 3D print ceramic objects. However, D’Halluin explained that Prodways has been able to expand the material set to include a wide range of metals.

Prodways’ MOVINGLight systems use one to two DLP projectors, mounted on an X-Y gantry, to cast UV light down onto a vat of photocurable resin. This setup allows Prodways’ ProMaker machines to take advantage of a robust build volume while maintaining rapid printing speeds. These combined strengths, then, position the MOVINGLight printers as batch manufacturing systems capable of high throughput.

The new material developed for the V6000 machine combines metal powder with a binder in such a way that Prodways is able to print a viscous, metallic paste quickly and with a fine level of detail. The printed object is then sintered in an oven, which burns out the organic binder and leaves only a dense metal object.

The ProMaker V6000 3D printer from Prodways is capable of 3D printing ceramic and, now, metallic pastes. (Image courtesy of Prodways.)
The ProMaker V6000 3D printer from Prodways is capable of 3D printing ceramic and, now, metallic pastes. (Image courtesy of Prodways.)

Creating the material was no easy task, according to D’Halluin. “The challenge to develop such a material is to combine three elements that are very hard to get together,” D’Halluin said. “You need to get some reactivity so that you can actually send the UV light to go deep enough into the material to cure it. You need to get the material to be stable enough so that it will cure quickly, but you also need a lot of metal powder in the material to actually be able to do the final sintering. The last requirement is that you need to be able to de-bind the metal powder and the binder so that you actually produce the final part when you put it in the oven.”

A 3D-printed metal part created with Prodways’ new metallic paste. (Image courtesy of Prodways.)
A 3D-printed metal part created with Prodways’ new metallic paste. (Image courtesy of Prodways.)

After much research, Prodways and the CEATech LITEN team were able to develop a metallic paste that is stable enough, cures quickly enough and contains sufficient metal powder to produce a metallic end part. The V6000 is able to spread a very thin layer of the paste, such that Prodways is able to cure a 50-micron layer in just one second using a variety of metal powders. So far, Prodways has printed with titanium and Inconel, but D’Halluin believes that it is also possible to print with copper, cobalt-chrome and steel.

Upon sintering, Prodways is able to achieve more than 90-percent density in the final metal component. For some applications, some porosity may not be a problem. D’Halluin suggests that, because the V6000 can achieve 99-percent density with ceramics, such a high level of density will be possible with metals as well.

Of the quality of the process, D’Halluin said, “We are able to get very accurate and very precise parts. That’s really coming from the precision of the DLP and we’re very happy with the surface finish of the parts that we have printed.”

The Benefits of MOVINGLight Metal 3D Printing

The ability to 3D print metal pastes brings some distinct advantages, both over traditional manufacturing techniques and metal 3D printing specifically.

“We are now able to explore a wide variety of metals. Now, it’s time to really explore what applications and what processes can benefit from this technology,” D’Halluin said. “Typically, we would have to approach applications that today use the metal injection molding [MIM] process.”

MIM also involves the combination of a fine metal powder with a binder; however, unlike with Prodways’ 3D printing process, this feedstock injected into a mold to create batches of parts to be sintered in an oven. D’Halluin explained that MIM is limited in that the feedstock is difficult to extrude, ultimately limiting the complexity and detail of the mold that can be used. Moreover, all molding processes are unable to produce certain geometries, such as those with interior cavities and tubes.

“We are bringing the flexibility of 3D printing to the MIM process and that is really what we are now going to explore in more depth,” D’Halluin said.

At the same time, 3D printing metal with MOVINGLight offers some benefits that other 3D printing processes such as direct metal laser sintering (DMLS) can’t. MOVINGLight is already a fairly rapid technology, capable of manufacturing sizeable batches of parts. The V6000 specifically has a build volume of up to 5 in x 20 in x 6 in (127 mm x 508 mm x 152 mm) and can print at up to five times faster than DMLS techniques. The combination of size and speed, in this case, would enable batch manufacturing of metal parts.

D’Halluin pointed out that there are other benefits as well. “With this process, eventually we believe that we will be able to bring about higher levels of productivity than other metal 3D printing processes, D’Halluin said. “However there are two other strengths, as well. One is the freedom of shapes. With our metal paste, you have no support structures. You remove all of the hassle of post-processing and removing supports from a metal part. And because of all of the milling required for post-processing metal parts printed with other processes, if you were to print a channel inside of an object, there is no way to do that and be able to remove the supports with a mill.”

Interior channels and other complex shapes impossible with DMLS are possible with metallic pastes and the cost, time and energy associated with refining a metal part and removing supports with a mill are also done away with.

D’Halluin added that printing with metallic paste avoids the health, safety and environmental concerns of dealing with very fine powders in a reactive gas environment, which are often associated with DMLS and other metal printing techniques. Because of these concerns, metal printers may be confined to clean rooms and operators must wear special suits and ventilators to avoid breathing in nanoparticles.

A Growing Portfolio

Israeli metal 3D printing company XJet has boasted similar benefits with its NanoParticle Jetting technology, such as the lack of support structures or dangerous materials. XJet has yet to begin manufacturing its metal 3D printing system, but they may end up competing in a similar space as Prodways when the latter begins selling its new metal materials.

When that will be is still unclear. D’Halluin pointed out that the company needs to continue research around its new materials. Though the process is refined, Prodways will begin exploring new verticals and applications for the technology.

Once the material does hit the market, however, Prodways will have some significant advantages over XJet in some ways. For instance, the French firm has a much more expansive portfolio than XJet, which only has one technology at the moment.

While Prodways is developing its metallic pastes, the company has been researching the use of its existing MOVINGLight technology for the indirect manufacturing of metal parts. Specifically, MOVINGLight can be used to produce objects for casting metal components.

Among the photopolymers used in the MOVINGLight process are tough thermoplastic-like materials, clear resins for creating surgical guides and resins that can be burnt out during the casting process. Prodways is further developing this last set to optimize the casting of metal parts and testing the process with companies in the aeronautic and automotive industries. D’Halluin explained that by 3D printing parts for investment casting with MOVINGLight, it’s possible to produce hundreds of parts at a time.

A turbine blade produced with lost wax casting using a 3D-printed model. (Image courtesy of Prodways.)
A turbine blade produced with lost wax casting using a 3D-printed model. (Image courtesy of Prodways.)

Additionally, last year Prodways partnered with Farsoon High-Tech, a manufacturer of SLS and DMLS machines. So far, only plastic SLS systems have been released under the “Prodways by Farsoon” brand.  D’Halluin explained that DMLS systems are on the horizon.

The acquisition of INITIAL and partnership with NEXTEAM Group allowed Prodways to launch its own 3D printing service bureau, providing the firm with the ability to begin competing with larger 3D printer manufacturers Stratasys and 3D Systems. Prodways’ service bureau subsidiary, INITIAL, has just another metal 3D printer, making it one of the largest metal 3D printing companies in France.

When looking at all of these developments together, the pictures is one of a rapidly growing company. In a previous interview with Groupe Gorgé CEO Raphael Gorgé, the executive explained that his wish was for Prodways to become the third leading player in the 3D printing industry. While these acquisitions and partnerships indicate that the firm is on its way to that status, it is new inventions like metallic 3D printing paste that could push Prodways well beyond third place.

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