1. Development of a Digital Standard to Specify Surface Requirements
Michelle Voelker
Frank Peters
Paul Kemper
Iowa State University
Industrial & Manufacturing Systems Engineering
SFSA Technical & Operating Conference December 10-12, 2015

2. Terminology
Abnormality- an anomaly of the surface exceeding two-times the baseline roughness
Abnormality Percentage- the percentage of the specified surface area containing abnormalities
Baseline Roughness- the roughness average of surface excluding abnormalities
Underlying Geometry- the surface geometry in absence of surface roughness and abnormalities
E3- Expansion
3 things we are going to specify, and 1 thing that will give us a standard way to calculate these things we specified.

3. Terminology
Abnormality- an anomaly of the surface exceeding two-times the baseline roughness
Abnormality Percentage- the percentage of the specified surface area containing abnormalities
Baseline Roughness- the roughness average of surface excluding abnormalities
Underlying Geometry- the surface geometry in absence of surface roughness and abnormalities
E3- Expansion
3 things we are going to specify, and 1 thing that will give us a standard way to calculate these things we specified.

4. Terminology
Abnormality- an anomaly of the surface exceeding two-times the baseline roughness
Abnormality Percentage- the percentage of the specified surface area containing abnormalities
Baseline Roughness- the roughness average of surface excluding abnormalities
Underlying Geometry- the surface geometry in absence of surface roughness and abnormalities
E3- Expansion
3 things we are going to specify, and 1 thing that will give us a standard way to calculate these things we specified.

5. Proposed Standard
Goal not to completely automate inspection; goal to create tool to verify visual inspection and automate qualification process.

6. Proposed Standard Determine underlying geometry
Calculate deviations from underlying geometry
Set bounds on abnormalities at twice the baseline roughness
Measure parameters from standard
Goal not to completely automate inspection; goal to create tool to verify visual inspection and automate qualification process.
Abnormal Points
Baseline Roughness

7. Proposed Standard VSR Notation VSR 1.2 – 2.4 –5 Default Values
Baseline Abnormality Abnormality
Roughness (mm) Level (mm) Percentage
VSR 1.2 – 2.4 –5
Default Values
Abnormality Level = 2x Baseline Roughness
Abnormality Percentage = 5%
Does not include chaplets/inserts, unusual visual conditions, dimensional accuracy

8. Surface Specification
How can we specify this surface profile?
VSR 1.85 – – VSR 2.32 – – 17
VSR 6.00 – – 0
Baseline Roughness ↑, Abnormality Percentage ↓
Baseline Roughness ↓, Abnormality Percentage ↑
VSR 1.85 – 12– 35
VSR 2.32 – 12 – 17 Exact Classification
VSR 6 – 12 – 0 Only want to specify range of abnormality (+/- 12)
Abnormality Level has to be at least 12
Abnormality Percent must be > # point further than 2*Baseline Roughness / Total number of points

9. Surface Specification
How can we specify this surface profile?
VSR 1.85 – – VSR 2.32 – – 17
VSR 6.00 – – 0
Baseline Roughness ↑, Abnormality Percentage ↓
Baseline Roughness ↓, Abnormality Percentage ↑
VSR 1.85 – 12– 35
VSR 2.32 – 12 – 17 Exact Classification
VSR 6 – 12 – 0 Only want to specify range of abnormality (+/- 12)
Abnormality Level has to be at least 12
Abnormality Percent must be > # point further than 2*Baseline Roughness / Total number of points

10. Surface Specification
How can we specify this surface profile?
VSR 1.85 – – VSR 2.32 – – 17
VSR 6.00 – – 0
Baseline Roughness ↑, Abnormality Percentage ↓
Baseline Roughness ↓, Abnormality Percentage ↑
VSR 1.85 – 12– 35
VSR 2.32 – 12 – 17 Exact Classification
VSR 6 – 12 – 0 Only want to specify range of abnormality (+/- 12)
Abnormality Level has to be at least 12
Abnormality Percent must be > # point further than 2*Baseline Roughness / Total number of points

11. Surface Specification
How can we specify this surface profile?
VSR 1.85 – – VSR 2.32 – – 17
VSR 6.00 – – 0
Baseline Roughness ↑, Abnormality Percentage ↓
Baseline Roughness ↓, Abnormality Percentage ↑
VSR 1.85 – 12– 35
VSR 2.32 – 12 – 17 Exact Classification
VSR 6 – 12 – 0 Only want to specify range of abnormality (+/- 12)
Abnormality Level has to be at least 12
Abnormality Percent must be > # point further than 2*Baseline Roughness / Total number of points

12. Surface Specification
How can these specifications be interpreted?
VSR 6.00 – – 0

13. Surface Specification
How can these specifications be interpreted?
VSR 1.85 – – 35
VSR 2.32 – – 17

14. Surface Specification
E3 SCRATA Comparator Sample
VSR 0.06 –

15. Surface Measurement Localized Roughness Shape Fitting
Flat surface example for standard roughness algorithms

16. Surface Measurement
Localized Roughness Shape Fitting
D5- Curvature

17. Surface Measurement Localized Roughness Shape Fitting
E3- Flat surface on top of the abnormality

18. Surface Measurement Underlying Geometry: Slicing Method
Segment Point Cloud into Slices and Data into Single Line
Fit Curve to 2D Segments of Data
Create Surface across Curves
A lot of parts have shrinkage and imperfect geometries so there is a need to find the underlying geometry for these calculations.
It’s not a problem to reverse engineer the original part of find the roughness EXCEPT when abnormalities are present.

19. Triangulate Subsampled Cloud to Create Surface
Surface Measurement
Underlying Geometry: Subsampling Method
Subsample Point Cloud
Triangulate Subsampled Cloud to Create Surface
A lot of parts have shrinkage and imperfect geometries so there is a need to find the underlying geometry for these calculations.
It’s not a problem to reverse engineer the original part of find the roughness EXCEPT when abnormalities are present.

20. Future Work
Investigate point density requirements for each classification
Compare point clouds to underlying geometry
Improved accuracy of roughness calculations
Improved isolation of abnormalities
List of suggested acceptance levels based on industry castings
Automated tool for checking standard on casting