Additive Manufacturing

AUG 2017

ADDITIVE MANUFACTURING is the magazine devoted to industrial applications of 3D printing and digital layering technology. We cover the promise and the challenges of this technology for making functional tooling and end-use production parts.

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AM / Building for Production additivemanufacturing.media 35 is by producing sample parts and testing them to measure the variation not just from machine to machine, but also for differ- ent positions of the build plate within the same machine. But as critical as it is to ensure repeatability across the additive systems, Collins says the build itself is only 60 percent of the entire additive manufacturing process. Other critical aspects include: • Materials. Tangible considers itself a beta house for AM production only, not for proving out materials or new equip- ment. Its focus is on finding the most affordable sources for its validated materials; keeping them inert before, during and after production; and figuring out how many times material can be reused. • Supports. "We don't design parts. We design supports," Clark says. The latter can present a design challenge comparable to the former. Providing enough support to hold the part during the additive build is critical, but it's also important to avoid overengineering supports and potentially damaging the build plate. Rather than fusing a part solidly to the build plate, Tangible makes an effort to design support structures that keep the part a little above the plate, making part removal easier. In some cases, building supports this way even makes it possible to remove the parts from the build plate by hand. • Build plates. The support strategy described above has another advantage: The ease of part removal protects the build plate from having excess material removed along with the part. It is important to prevent this because a plate that becomes too thin will not be able to stand up to the distor- tion caused by the powder-bed process. Ultimately, these plates—vital pieces of tooling—will be tracked and logged in an ERP system just like production parts. • Postprocessing. Currently, when built parts are completed, they are removed from the machine via a glove box and then an employee wearing personal protective equipment (PPE) washes the parts with liquid, typically deionized water or mineral oil. The parts are then removed from the build plate, either by hand or using the wire EDM. From there they may go into a blast cabinet or travel off-site for processes such as heat treatment or HIPing. Each of these steps introduces variables that need to be standardized and documented. • Inspection. Tangible is still working through validating the inspection process for medical devices. Methods currently being explored include the use of hand gages and a 3D scanner in-house, and outsourced methods such as CT and radiograph- ic scanning; but ultimately, the inspection choice will depend on customer needs, wants and budget. By proving out the con- sistency of the AM process, Tangible is accruing data that will keep inspection from being a burden. "By building that case, we are allowing ourselves the freedom to not inspect every single part," Collins says. Beyond the technology, there's also a human element to be addressed. "A bottleneck for our industry right now is workers," Clark says. That's one reason Tangible has made a significant effort to partner with local community colleges such as Cincinnati State and Sinclair Community College. It's also looking at local high schools as a potential source of employees. One of its most recently hired employees is an 18-year-old graduate who earned experience with machining, EDM and other conventional tech- nologies while in high school. Even so, "We're running on a skeleton crew right now," Collins says. The company has 11 employees currently, but hopes to grow that number to 20 or 25 by the end of 2017. Maintaining and in- creasing the workforce will be an ongoing challenge, he says. Next Steps There's plenty of room to grow in the Fairborn facility, but what that growth looks like in the immediate future is not yet obvious. "The bottleneck could be machining, so maybe we'll need another CNC next," Collins says. "Or maybe it'll be adding another plastics printer." The ultimate plan is to "duplicate and segregate," Clark says. After solidifying the medical business, the lessons learned will be used to establish Tangible Solutions Aerospace. The aerospace industry is ready for additive manufacturing, Clark says, but not yet for contract additive manufacturers. When it is, Tangible hopes to help fill that void. Tangible tends to design supports that hold the parts a little above the build plate, which makes it easier to cut them off with the wire EDM. Then, the remaining support structures are machined away to prepare the plate for another build.

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