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• Build parameter adjustment

• Build orientation

• Powder characteristics

• Post processing

Published research Why has AM surface been measured?

• Build parameter adjustment

• Build orientation

• Powder characteristics

• Post processing

Function?

Published research Why has AM surface been measured?

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Focus variation [11%]

Confocal microscopy [11%]

SEM [11%]

Coherence scanning interferometry [8%]

Optical microscopy [7%]

Chromatic confocal [4%]

Conoscopic holography [4%]

(AFM [4%])

XCT [4%]

Raman spectrometer [4%]

(Review of 100+ publications)

Contact areal [4%] [1] Non-contact areal Contact stylus [40%]

Published research Measurement method

Microgeometry capture using an elastomeric sensor

Johnson, Micah K, Cole, Forrester, Raj, Alvin and Adelson, Edward H 2011 1.

Profile measurement (ISO 4287:1998)

• Ra (Arithmetic mean deviation of the assessed profile) [41%]

• Rq (Root mean square deviation of the assessed profile [std. dev.]) [18%]

• Rz (Maximum height of profile [within sampling length]) [12%]

• Rt (Total height of profile [within evaluation length]) [6%]

• Rsk (Skewness of the assessed profile) [6%]

• Rku (Kurtosis of the assessed profile) [6%]

• Material ratio curve of the profile (Abbott Firestone curve) [6%]

Published research Surface texture parameters

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Same Ra value

Pit or scratch? [1]

Published research Surface texture parameters

Why use areal surface texture measurement?

DMAC Meeting, University of Huddersfield. L. Blunt. 2006 1.

Areal measurements (ISO 25178-2:2012)

• Sa (Arithmetic mean height of the scale-limited surface) [12%]

• Sq (Root mean square height of the scale-limited surface) [6%]

• Sal (Autocorrelation length) [6%]

• Str (Texture aspect ratio) [6%]

• Std (Texture direction of the scale-limited surface) [6%]

• Sdr (Developed interfacial area ratio of the scale-limited surface) [6%]

• Sk (Core height) [6%]

• Spk(Reduced peak height) [6%]

• Svk (Reduced dale height) [6%]

• Smr2 (Areal material ratio [dales]) [6%]

• Vmp (Peak material volume of the scale-limited surface) [6%]

• Vmc (Core material volume of the scale-limited surface) [6%]

• Vvv (Core void volume of the scale-limited surface) [6%]

Published research Surface texture parameters

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Areal measurements (ISO 25178-2:2012)

• Sa (Arithmetic mean height of the scale-limited surface) [12%]

• Sq (Root mean square height of the scale-limited surface) [6%]

• Sal (Autocorrelation length) [6%]

• Str (Texture aspect ratio) [6%]

• Std (Texture direction of the scale-limited surface) [6%]

• Sdr (Developed interfacial area ratio of the scale-limited surface) [6%]

• Sk (Core height) [6%]

• Spk(Reduced peak height) [6%]

• Svk (Reduced dale height) [6%]

• Smr2 (Areal material ratio [dales]) [6%]

• Vmp (Peak material volume of the scale-limited surface) [6%]

• Vmc (Core material volume of the scale-limited surface) [6%]

• Vvv (Core void volume of the scale-limited surface) [6%]

Published research Surface texture parameters

Scale of interest?

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Scale of interest?

Dune buggy suspension?

Cut-off 500 m

Arithmetic mean height 10 m?

Scale of interest?

Dune buggy suspension?

Cut-off 500 m

Arithmetic mean height 10 m?

Wind-ripple generation?

Cut-off 0.2 m

Arithmetic mean height 2 cm?

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Scale of interest?

Dune buggy suspension?

Cut-off 500 m

Arithmetic mean height 10 m?

Wind-ripple generation?

Cut-off 0.2 m

Arithmetic mean height 2 cm?

Abrasiveness?

Cut-off 0.2 cm

Arithmetic mean height 0.1 mm?

Scale of interest?

Dune buggy suspension?

Cut-off 500 m

Arithmetic mean height 10 m?

Wind-ripple generation?

Cut-off 0.2 m

Arithmetic mean height 2 cm?

Abrasiveness?

Cut-off 0.2 cm

Arithmetic mean height 0.1 mm?

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Scale of interest?

DEFECT?

Scale of interest?

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Scale of interest?

µm

Scale of interest?

km

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New Horizons mission

NASA/JHUAPL/SwRI SEM image Ti6Al4V

Scale of interest?

SEM image AlSi10Mg

Scale of interest?

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SEM image AlSi10Mg

Scale of interest?

SEM image AlSi10Mg

Scale of interest?

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SEM image AlSi10Mg

Scale of interest?

Importance of AM surface topography

Defining a “good” surface based on functionality

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Importance of AM surface topography

Defining a “good” surface based on functionality

Linking a “good” surface to suitable surface inspection parameters

Importance of AM surface topography

Defining a “good” surface based on functionality

Linking a “good” surface to suitable surface inspection parameters

Linking surface inspection parameters to AM build variables

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Importance of AM surface topography

Defining a “good” surface based on functionality

Linking a “good” surface to suitable surface inspection parameters

Linking surface inspection parameters to AM build variables

Defining and standardising AM surface inspection parameters

SEM image AlSi10Mg

Metal powder bed fusion AM surface

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• Cube 10 mm per side • 100 µm powder thickness

• 100 µm line spacing

Approximate percentage of total surface area produced during the manufacturing process remaining as outside surface on

completion:

3%

Importance of AM surface topography

Embedded surface example (powder bed fusion)

Surface <-> porosity?

Reconstruction from xCT showing porosity analysis

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Which surface? Feature analysis -motif analysis and segmentation

AlSi10Mg sample, Renishaw AM250, Alicona Infinite Focus G4

• Extract “outcrops / peaks”

• Analyse underlying surface

• Analyse “outcrops / peaks”

• Process control?

Re-entrant features?