Modern Machine Shop

JUL 2018

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Page 45 of 147

ADDITIVE INSIGHTS MMS JULY 2018 44 Understanding Industrial 3D Printing Kwik Mark Inc Dot Peen Marker · Type or teach positioning · Compact flash card memory · Automatic serializing · Date/time shift coding · Mark virtually any material · True chipless engraving Contact us today · · · (815) 363-8268 · The KM-64 · American Made A R C T E X T S E R I A L : 0 0 0 1 1 7 - 2 1 - 1 7 1 8 : 2 7 Impo rt Graphics ANGULAR TEXT A N G U LA R TEXT MIRROR TEXT MIRROR TEXT REVERSE TEXT REVERSE TEXT 2D DATA MATRIX build process was not. Each service bureau could orient and additively manufacture the part how- ever they wanted. This test simulated the same "hand off " that designers are used to making with traditional manufacturers. The lack of build-process specification resulted in drastically different parts. Figure 2 shows two of the AM test parts, highlighting the warped edges, non-uni- form surfaces, missing fins, support struc- tures that were not removed and other issues. Further analysis in our computed tomography (CT) scan- ner revealed that the part that looked the best on the outside was actually the worst on the inside (see Figure 3) while the one that looked the worst on the outside was the best on the inside. So, what happened? Well, design was "divorced" from manufacturing in this case, and the team did not get what it designed. One ser- vice bureau oriented the part to ensure that the internal features printed well, another focused more on the external features and the third tried a compromise between the internal and external features. No matter how the part is oriented, it is very difficult to print, and everyone learned a valuable lesson. Without specifying (designing) the build, AM producers are going to do what is best for them, which is typically reducing build time and mate- rial utilization. This often means picking an ori- entation that minimizes build height, which can cause all sorts of headaches when it comes to post processing and finishing (machining) AM parts. This is not intended as a critique of AM service bureaus. Rather, it reinforces the importance of designing the part and designing the build when it comes to AM. SPEAKING OF DESIGN The effect of gas flow within the build chamber has a lot to do with how you orient a part: AUTHOR | Timothy Simpson Professor of Engineering Design & Manufacturing Pennsylvania State Univeristy

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