Modern Machine Shop

JUL 2018

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ADDITIVE INSIGHTS MMS JULY 2018 42 mmsonline.com Understanding Industrial 3D Printing Reuniting Manufacturing and Design for Effective AM As a machining professional or manufacturing expert, how many times do product designers or engineers tell you how to make a part? I am guessing rarely, if at all, just like you do not tell them how to design or engineer their parts. Instead, they specify geometric dimensions and tolerances for each component that they want you to manufacture, and then you tell them the best way to make it to meet those specifica- tions. Once they realize how expensive he compo- nents are to make with the current specifications, they tweak the tolerances and iterate until both parties reach a compromise. With additive manufacturing (AM), specifying how the part will be built is just as important as designing the part itself. So, when engineers are designing new parts to be made with AM, they have to think just as much about build orien- tation and layout as they do the geometry and features being designed into their parts, other- wise, they may not get the part they designed. Consider the test part in Figure 1, which was designed by Andrew Coward, a Ph.D. student working with Dr. Karen Thole at Penn State to evaluate AM for gas-turbine applications. The test part was designed with features that are typical of these applications: small, internal piping; orifices; protrusions; thin walls; fins and more that are oriented in different directions. The 3D solid model was sent to three AM service bureaus that were asked to manufac- ture it in a readily available metal alloy. The CAD file and material were specified, but the TIMOTHY W. SIMPSON | COLUMNIST Designing the build is just as important as designing the part. FIGURE 1: This test par t, viewed from the front and rear, was designed by Andrew Coward and Dr. Karen Thole at Penn State for gas-turbine applications. FIGURE 2: Warping and malformed fins (lef t) and suppor t structures (right) are just some of the defects in the returned AM test par ts. FIGURE 3: The AM test par t that looked the best on the outside revealed broken piping on the inside via a CT scan. FIGURE 1: FIGURE 2: FIGURE 3:

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