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Metals 2016,6, 313
To conclude, layer thickness is one of themajor factors influencing the formingmorphology.
Different layer thicknesseswillproduceacompressionora jet.Whenthe layer thickness is larger than
1.5mm, themoltenmetal jetwillnegativelyaffect the freesurfaceof themelt,usuallycausingdamage
to theprevious layers ormassive overflowing. When the layer thickness is smaller than 1.2mm,
thewidth of thin-wall specimens increases due to the nozzle extrusion pressure and, as a result,
usuallyreduces the formingefficiency. Theflat formingmorphologycanbeachievedwhenthe layer
thickness isbetween1.2mmand1.5mm.
The forming morphology of the workpieces in Figure 4b,c are better than the others.
Consequently, the process parameters of these twoworkpieceswere applied to forma thinwall,
asshowninFigure5. InFigure5a, thepreviousseveral layersweredepositedwithagoodoverlapping
rate.However, thecumulativeerrormadethebondingqualitydecrease,andtheporosity increased
duringthesubsequentdepositionswhenthe thicknesswas1.5mm. InFigure5b, the layer thickness
matcheswellwith theheightof theactual specimens. The idealworkpiecewasobtainedwithoutany
defects, andthemorphologyofeach layerwasuniformwhenthe thicknesswas1.2mm.
Figure5.Thedepositedspecimens indifferent layer thickness. (a)δ=1.5mm. (b)δ=1.2mm.
3.3.WavinessandCross-SectionMorphologyAnalysis ofThin-WalledSpecimens
The layer thickness and surface quality remain themost important issues to be taken into
considerationforthethin-walledexperiments.Thewavinesswasappliedtoevaluatethesurfacequality,
includingthreemajorindexes(Wa,WqandWz).Theindexes,Wa,Wq,andWz,denotethearithmetical
meandeviationof theassessedprofile, therootmeansquaredeviationof theassessedprofile,andthe
maximumheightof theassessedprofile, respectively. Inaddition, itwasfoundthat thewavinessof the
formedspecimens isgreatlyaffectedbythe layer thickness.As illustrated inFigure6a, the thin-walled
specimenwasformedbasedonthefollowingprocessparameters: adepositionvelocityof18mm/s,
aflowrateof50mm3/s,anda layer thicknessof1.2mm.Thecrosssectionof thespecimenisshown
inFigure6b,andthecorrespondingmeasureddatawasshowninFigure6c. Thewaviness indexes
wereanalyzed,andtheresultsareas follows:Wa=0.9448,Wq=0.963,andWz=0.303.
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book 3D Printing of Metals"
3D Printing of Metals
- Title
- 3D Printing of Metals
- Author
- Manoj Gupta
- Editor
- MDPI
- Location
- Basel
- Date
- 2017
- Language
- English
- License
- CC BY-NC-ND 4.0
- ISBN
- 978-3-03842-592-2
- Size
- 17.0 x 24.4 cm
- Pages
- 170
- Keywords
- 3D printing, additive manufacturing, electron beam melting, selective laser melting, laser metal deposition, aluminum, titanium, magnesium, composites
- Categories
- Naturwissenschaften Chemie