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another constraint. Te laser is fixed and then steered to the powder bed with mirrors. Te beam can experi- ence problems when it is redirected farther and farther from the center of the build box. Tese complications can lead to components that are out of tolerance, variances in the laser’s energy and other complications. Cur- rently, powder bed fusion is restricted to build boxes with axes around 10 in. Binder jetting systems can produce larger parts, but are still constrained by the size of the build box. 3-D printing methods are some- what limited by the materials available for use. Te number of alloys that can be used for powder bed fusion is only a few dozen, including stainless steel 316, Inconel 625 and 718, titanium Ti64 and a cobalt-chrome alloy. Tese offers should increase as the technology develops and the industry continues to invest in R&D. “DMLS is a microwelding process.


In principle, if you can weld an alloy, it’s a candidate for DMLS,” said Snow. “Te products that have been brought to market and commercialized are the low hanging fruit, developing applica- tions for titanium, stainless steels and nickel-based alloys. Tese are materials that the marketplace is telling us they want first and we’ve delivered those.” Similarly, for binder jetting, only a handful of materials, including 316 and 17-4 stainless steels, an iron-chrome-alu- minum alloy and a cobalt chrome alloy, can be infiltrated with bronze to produce metal matrices that are 98% solid. In addition to diversifying materials,


direct metal printing faces a number of challenges associated with a technol- ogy’s natural maturation process. Traceability, supply chain, repeat-


ability, reliability, real time control, software simulation—all these things have been worked out with other industries such as metalcasting,” Caf- frey said. “Tese are things that have yet to be solved for our industry.” But the future is still bright. Con-


sidering 3-D metal printing’s ability to penetrate the medical and aero- space industries, two markets notori- ously demanding and risk averse, the obstacles of meeting requirements of other industries in other materials do


By building components one layer at a time, powder bed fusion can produce complex shapes.


not appear insurmountable. “We’ve used 3-D printing for plastic


tooling, so it only makes sense that metal is the next step,” said Brandon Lamoncha, sales manager, Humtown Products, Columbiana, Ohio. “Te industry should embrace this technol- ogy when it makes sense, and we’ve seen that start to happen.” Humtown Products, the


Youngstown Business Initiative and American Foundry Society helped launch the American Makes initia- tive, an effort to facilitate collabora- tion among leaders from business, academia, non-profit organizations and government agencies to make the U.S. 3-D printing industry more globally competitive.


Finding Space on the Factory Floor The potential for direct metal


printing is real, but the technology should be seen as complementary to traditional metal component manu- facturing and doesn’t pose a major threat to metalcasting facilities in the near future. “I think all comes back to scal-


ability of the process. I firmly believe we need to get to a point where the economies of scale makes sense, like in many traditional methods of manufac- turing,” Ewan said. “If that’s possible, I think [direct metal printing] will be one more tool along with metal casting, subtractive methods like CNC machining and other manufacturing methods. Tey all kind of dovetail— where one is strong, another is weak.” Even if 3-D metal printing


becomes more widespread in manu- facturing, the technology is a poten- tial partner for a hybridized produc- tion method. Just as 3-D-printed molds allow investment casting facilities to have rapid prototyping capabilities, direct metal printing may provide the industry with improved capabilities. “A lot of people have this misun- derstanding of additive manufactur- ing that it’s going to be a technol- ogy that will displace many of the traditional manufacturing processes like milling and grinding,” said Snow. “But it’s the exact opposite. We need to coexist and depend on each other for secondary finishing. We don’t see this as a threatening technology to the current structure of manufactur- ing. It’s a complementary piece of equipment that’s another tool on the factory floor.” 3-D printing, including the addi-


tive manufacturing of metal parts, will continue to be a hot topic in the years to come. Te developing technology is definitely worth following, even if its significance in manufacturing appears to be gradually increasing in the coming years and decades. “People hint about the third


industrial revolution that’s going to change everything,” Caffrey said. “But a more realistic scenario is a sophisti- cated contract manufacturer will have a factory floor that’s going to have all kinds of machine tools. Te more high tech operations may have cast- ings capabilities, and they may have additive metal technology.”


May 2015 MODERN CASTING | 49


Photo courtesy of EOS


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