Modern Machine Shop and MoldMaking Technology present ADDITIVE MANUFACTURING, a quarterly supplement reporting on the use of additive processes to manufacture functional parts. More at additivemanufacturinginsight.com.
Issue link: https://am.epubxp.com/i/542042
6 — AM Supplement 6 — A M S u p p l e m e n t F E A T U R E new additive manufacturing machine brought the company the capability to produce critical metal production parts through an additive layering process, Lanigan says it became clear that this represented a change that went far beyond the possibilities of the shop's previous 3D printing. "I had the same thought others did," he says. "I thought, 'Wow, we will have to retrain our engineers.'" Indeed, getting free of the unseen conceptual constraints harbored by experienced designers is a challenge the Deka team now continually confronts. Lanigan says, "When we design a part for additive, we look at the design and try to ask: Is this crazy enough?" Additive manufacturing permits elaborate geometries, and it realizes its full value when that freedom is embraced. "The dan- ger is always that there is an even better design to be obtained through an even crazier geometry that we're not able to see yet, because we are still locked into traditional ways of thinking about parts." Because of this kind of inquiry and design explo- ration, additive manufacturing actually works best in an environment like Deka's in which designers and manufacturers work together. Design personnel sitting close to manufacturing personnel is what this process needs, Lanigan says. That makes it different from machining. Another difference: trial and error. Precisely how a given part will form within an additive build is impossible to predict, he says. Residual stress during part formation might cause unacceptable distortions, and fnding the way to avoid those distor- tions might involve changing the part orientation as well as adjusting process parameters such as layer thickness or laser scan speed. Because of this need to fnesse the process, Lanigan says it is reasonable to expect to build any new additive part three or four times before getting to a successful process. This experimentation proceeds slowly, he says—the cycle to grow a Stirling engine heater head, for example, takes 22 hours. Thus, additive manufacturing is not a process for the impatient or the easily frustrated. Heater Head The heater head is the Stirling engine component that has benefted the most from additive manufac- turing. This component is the heat exchanger at the heart of the engine's operation. Flame flls the center The heater head has previously been made in Inconel 625. The image above shows Deka's attempts at additively building it in two different orientations. The image at right shows how the custom shape of fuid passages in the additive manufactured version presents a profle that better captures the heat than the previous assembly, which used standard round tubing.