Seite - 57 - in 3D Printing of Metals

Metals 2017,7, 91 Table2.Overviewofenergy-relevantprocessparametersusedtobuildall samples,SLMprocess. Parameter Description Unit ProcessParameter P LaserPower W 275 v Scanspeed mm/s 805 d Hatchspacing μm 120 t Layer thickness μm 50 Table3.Overviewof theenergy-relevantprocessparametersusedtobuildall samples;EBMprocess. Parameter Description Unit ProcessParameter P Beamcurrent mA ~21 Accelerationvoltage kV 60 v Scanspeed mm/s ~4530 d Hatchspacing μm 100 t Layer thickness μm 50 2.3.Measurements A digital microscope—Keyence VHX 2000 (KEYENCE Deutschland GmbH; Neu-Isenburg, Germany,)—wasused for thedeterminationof themanufacturingquality, inparticular, of the real crosssectionof thepartsandofpartdimension. Foreachorientationanddiametervariation, thecross sectionsweremeasured. For thismeasurement, thestruts fromonepartwereremovedandimbedded in resin. The surfaceswere polished, and after ameasurement, someμmfrom the samplewere removedforanewmeasurement. Thispartwasproducedtogetherwith theparts intendedfor the pressure test. Every result for the cross sections consisted of 10measurements. For a qualitative judgment, theexternaldiametersaswellas the innerdiameterofacircleweredetermined in thecross section(Figure5). Figure5.Sampleofcrosssectionareaandthemeasureddiameter inside thecrosssectionareaas inner diameteraswellas theexternaldiameter. In thispicture is seena45◦orientedSLMpart. Surface quality measurements (Figure 6) were performed with a 3D digital laser-scanning microscopeVK-X260(KEYENCEDeutschlandGmbH;Neu-Isenburg,Germany)accordingtoISO25178. Ra, as thearithmeticaverageof theabsolutevalues,andRZ,as themaximumheightweredetermined, respectively, for theSLMandEBMparts inbothorientations (0and45◦).Measurementswerecarried outonall fourstrutsofapartaftermanufacturingbefore themechanical testingontheoutsideof the 57