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Directed energy deposition shapes the future of additive

Kip Hanson
By Kip Hanson Contributing Editor, SME Media

Mike Dean, vice president marketing for Optomec, discusses the particulars of the company’s LENS technology.

Mike, what differentiates Laser Engineered Net Shaping (LENS) technology from Directed Energy Deposition (DED) metal 3D printing?

LENS is the Optomec brand name for Directed Energy Deposition. The proprietary term LENS was actually around before the industry settled on “DED” as the generic name, as recently specified in ISO/ASTM 52900.

When it comes to turbine blade repair, DED is the go-to solution. This helps explain why Optomec has installed nearly 100 machines for this application, with more than 10 million blades repaired thus far.

Aren’t DED and LENS primarily used for repairing and adding to existing parts, such as turbine blades, whereas Laser Powder Bed Fusion (LPBF) is best for building them for scratch?

Actually, DED is used for building and repairing parts, and for adding specialty surfaces to parts. LPBF, on the other hand, is primarily used for building. In either case, DED has the advantage of being much faster (10X) and less expensive than LPBF (5X). It can also be used to create bi-metallic structures—a rocket nozzle, for instance: One that might have a high-temp, corrosion-resistant alloy on the inside and a copper-based, high-heat transfer alloy on the outside. DED is also capable of printing much larger parts, whereas LPBF is limited to the size of the build chamber. Materials researchers also prefer DED because it allows them to blend multiple streams of powder, creating several different compositions of an alloy by simply changing the process parameters. This is why Optomec machines are available with multiple programmable powder feeders that converge in the print head.

A little longer than two years ago, Optomec acquired Huffman, which is focused on DED-based gas turbine repair. Hasn’t that led to two competing product lines?

It might look like that at first glance but the product lines are actually complementary. Optomec’s LENS machines were targeted at a wide set of applications and materials and are therefore available with scores of options. These include oxygen-free processing chambers, thermal imagers, various laser options, the ability to add material, as well as machine it in the same equipment, and so on. The Huffman line took on a more vertical strategy, optimizing all aspects of the machine for the high-volume gas turbine component repair segment. It includes features, such as robotic automation and integrated vision with adaptive software, that accounts for the slight part-to-part variation in turbine components seen during repair operations. Now the best capabilities of each product line have migrated into the other, so we’re seeing synergy on the technology side. For instance, we’ve ported the LENS oxygen-free processing technology to our latest machine for repairing titanium aviation parts, opening up new applications for our aerospace customers.

LENS makes it possible to blend up to four different metals in the same build, right? What are some of the applications for this capability?

I mentioned bi-metallics like the rocket nozzle. I also mentioned custom alloy development for materials research. Another common application is where you need to transition from one alloy to another that bears very different mechanical properties. In cases like this, an abrupt transition could lead to cracking or distortion, so our customers typically avoid this by starting the build with the first alloy in its pure form, then gradually increasing the percentage of the second alloy with each subsequent layer until reaching its pure form. This alleviates the stress caused by disparate thermo-properties.

Won’t manufacturers face significant hurdles in attempting to qualify these novel materials for commercial or military use?

It depends. Many of our customers are in the business of material development and will qualify their own materials. As an example, an automotive OEM might experiment with different DED-added wear coatings and put them through testing for improved part life, in which case they would qualify their own proprietary material. On the other hand, an MRO supplier remanufacturing aviation parts must stick to OEM-specified materials, which would typically be FAA approved. 

Optomec is also quite active in 3D printed electronics, namely “advanced semiconductor packaging.” What are some of the more important trends in this industry, and why?

The electronics industry is undergoing a big change, driven by two main demand forces: miniaturization and higher frequency integrated circuits (ICs). Miniaturization is pretty straight forward: Consumers want more features in smaller packages, such as cell phones, which has implications for the way ICs are connected to one another. The incumbent technology—wire bonding—is pretty much at its miniaturization limit in terms of interconnect geometry. Because of this, customers are turning to Aerosol Jet printed interconnects, which can be placed closer to one another and have virtually zero height. With regard to high frequency ICs, the demand is exploding, driven by a huge increase in things like 5G components, automotive radar and defense applications. Again, the incumbent technology is wire bonding, and it’s terrible at coupling signal frequencies over 30 GHz: It simply kills the signal throughput due to high impedance losses. Therefore, we are seeing a lot of interest in Aerosol Jet interconnects for these emerging applications. Printed interconnects have much lower inductance and can be custom-shaped to minimize the losses in the conductors. This increases the circuit’s performance, reduces power consumption, and lowers the IC operating temperature, which leads to longer IC life in many cases.

It’s evident that AM is becoming a mainstream process. What advice would you give to manufacturers looking to adopt this technology?

On the metal AM side and the printed electronics side, my advice would be to remember that, whether you’re doing R&D, prototyping, repair or new part production, you have to keep in mind that the AM machine is only half of the solution. The other half is comprised of process recipes and applications support. That’s why Optomec made the decision to offer several levels of these recipes for our machines, from starter recipes for common materials to part-specific, detailed production recipes. The goal is to drastically shrink the learning curve and therefore maximize equipment ROI.

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