Manufacturing Engineering: ExOne is seeing continued success in the sand and investment casting industry. Does 3D sand printing spell the end of traditional patternmaking?
Rick Lucas: Just as 3D printing didn’t signal the end of traditional forming technologies for plastic or metal, sand 3D printing isn’t likely to spell the end of traditional patternmaking anytime soon. Every technology has its sweet spot where it delivers the highest benefits. For our sand 3D printing technology, we believe this is the way cores, especially complex cores, were meant to be made. We have customers dramatically cutting back on core assembly with our technology, going from 10-20 separate core pieces that need to be assembled to just one. Along the way, they eliminate inefficiencies and also improve the quality of the part and eliminate scrap, which is a natural consequence of manual assembly of core pieces. Wherever there is complexity, our approach delivers extreme value and it’s also unlocking new capabilities to make new designs that are advancing electric cars and other innovations.
ME: Thanks to this success, many think of ExOne in terms of its toolmaking capabilities. What else are you good at?
Lucas: First of all, we love toolmaking, and we don’t just 3D print sand tools. We actually have the broadest portfolio of 3D printed tooling options in 3D printing today. Customers, of course, use our sand printers for metal-casting tools, but we also sand 3D print forms that are infiltrated for large-format thermoforming and composite tools. Our metal binder jet systems also directly print tools for plastic injection molding and blow molding, in addition to direct end-use parts. A lot of those are other types of tools, too, such as end-of-arm tooling for robots or wear tools. But we also direct print final metal, composite, and ceramic parts for a wide range of applications, primarily in the automotive, aerospace, defense and energy industries, with more medical applications coming.
ME: Why is binder jet, and ExOne in particular, named as “an innovative, faster and more agile method of generating parts for rapid product development and production?”
Lucas: The material processing strategy of binder jetting is simply a faster approach than other forms of 3D printing, which rely on singular points, such as lasers or nozzles, to draw out parts one by one. By using a gantry of printheads to drop binder across a wide swath of a powder bed, we can simply build each layer faster, which is more efficient and also relatively cheap. Printheads are much more affordable than lasers, and there are other benefits, too. For example, binder jetting offers material flexibility. We can bind just about anything that can be pulverized into powder: metal, ceramics, sands, concrete, wood fiber, refuse—you name it, we can print it.
ME: Your website refers to ExOne’s binder furan as a green product, yet the FDA lists it as a carcinogen. Can you clarify this for our readers?
Lucas: Sure. While we do offer inorganic binders that don’t emit gas, most of our customers still prefer to use furan, a material they commonly use in traditional sandcasting products and are familiar with. While furan isn’t perfect, it is derived from natural sources such as corn husks, rice hulls and sugar cane, and we’re looking forward to the market’s shift toward the inorganic binders that we offer.
ME: You’ve partnered with Rapidia, a company that offers “debind free” 3D printing. Why is this a big deal?
Lucas: The ExOne Metal Designlab, which is offered through our exclusive partnership with Rapidia, is the only true “print today, parts tomorrow,” office-friendly metal printing system on the market. The whole system is enabled by HydroFuse, a groundbreaking water-based paste containing metal powders that offers many benefits. Unlike competing systems that pre-bind metal in filament or rods, usually with a lot of binders, HydroFuse has a tiny amount of binder in it, eliminating the debinding step and speeding up the sintering phase. Because there’s so little binder, we can also print full-thickness parts, which none of our competitors can do.
ME: As a follow-up to the last question, are there any other industry partnerships you care to highlight?
Lucas: ExOne has a wide range of university, R&D and government partnerships globally, from Virginia Tech and University of Texas at El Paso to Oak Ridge National Laboratory to the Fraunhofer IFAM in Europe. We also support a wide range of government programs, such as a recent U.S. Department of Defense project to build a 3D printing pod in a shipping container. That project is exciting and in full swing. We’re always looking to collaborate with partners to solve problems where we think binder jetting can deliver a unique solution.
ME: ExOne advertises binder jetting as a “sustainable manufacturing technology.” How so, and is this any different than other 3D printing technologies?
Lucas: ExOne offers many of the same sustainability benefits as other technologies but we stand out in some very important ways. Key among them: our technology lets manufacturers reuse more than 96 percent of the powder directly in the process without standard recycling, where you have to send the waste out and have it reprocessed before reuse. You can reuse powder directly in our process, which is truly unique, and research has been done on this topic. But the most important sustainability benefit our technology can deliver is high-volume production of more sustainable parts with less waste. So while most forms of 3D printing can deliver that, we can do it at low cost and high speed, which makes those sustainability benefits more meaningful.
ME: To the machining world, your work with cutting tool materials such as silicon carbide, cobalt and tungsten is intriguing. What are some of their uses? Are these materials challenging to print?
Lucas: As I mentioned, we can print virtually any powder. But it can take time to optimize the process for certain particle sizes and densities that may be required for certain applications. Binder jetting is pretty simple, but each material has its own dynamics and relationships with different binders and parameters that we have to dial in. Fortunately, we have a lot of experience with different materials and binders, so we feel confident that we can process almost any powder today. At the end of the day, we have customers printing a wide range of metals and technical ceramics for optical components, nuclear reactor fuel cells and heat exchangers, in addition to tooling and wear tools. It’s truly an exciting time to be in binder jetting, and we see new applications every day.
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