1. RC Metrology Consulting rcmetrology@yahoo.com

2. What does it measure? Know the uncertainty of your CMM using a $10 calculator…

3. Outside the Box  “So we fix our eyes not on what is seen, but on what is unseen. For what is seen is temporary, but what is unseen is eternal…”

4. Outside the Box

5.   1 + 3 = 2²   1 + 3 + 5 = 3²   1 + 3 + 5 + 7 = 4²   1 + 3 + 5 + 7 + 9 = 5²   1 + 3 + 5 + 7 + 9 + 11 = 6²   1 + 3 + 5 + 7 + 9 + 11 + 13 = 7²   1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 = 8²   1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 = 9²   1 + 3 + 5 + 7 + 9 + 11 + 13 + 15 + 17 + 19 = 10²

6. CMM game plan  Order it up…  We will establish a strategic, easy to implement, statistical system to learn the certainty of any given CMM application  Plan, Do, Check, Action…

7. Our Goal  To improve the measurement capability of our CMM by increasing the certainty of the measurements we are making.  This improvement may seem to be very small.

8. Small Improvements  The difference between a career in the Minor Leagues and the Baseball Hall of Fame is only 1 more hit per week.  A Baseball season is played April – September = 26 weeks

9. The Minor Leagues  In a normal season a player will encounter 500 at-bats.  125 hits in 500 at-bats…  125 / 500 =.250 batting average.  Toledo Mudhens

10. Imagine if ???  If a player could get just 1 more hit per week…  151 hits in 500 at-bats…  151 / 500 =.302 batting average.  The Hall of Fame

11. Uncertainty???  ISO-9000, QS-9000:1994, state: “Inspection measurement and test equipment shall be used in a manner which ensures that the measurement uncertainty is known and consistent with the required measurement capability.”

12. Uncertainty???  TS-16949: Recommends internal inspection labs comply with ISO/IEC 17025… “When estimating the uncertainty of a measurement, all uncertainty components which are of importance in the given situation shall be taken into account using appropriate statistical methods of analysis.”

13. Uncertainty???  Doesn’t it?  Can’t we?  Right???  Isn’t it?  Don’t they?

14. Uncertainty is:  The upper estimated limit of how wrong a given reading (or value) can be.  Kerry 53% Bush 47% (±4%)  Kerry 57% Bush 43%  Bush 51% Kerry 49%

15. The True Value is:  Always unknown and unknowable (MSA 3 rd edition)  Average value taken from an infinite number of readings.

16. The Plug Gage Paradox  Tell me what it measures: Outside Diameter.  Caliper (.001”)  Micrometer (.0001”)  Bench micrometer (.00005”)  How many readings (1,3,9,12)

17. The Plug Gage Paradox  Where do we measure? (on the end or in the center)  What if it’s not round (and it won’t be)  Diameter ????????

18. The Plug Gage Paradox  Because the measurement definition was not clearly defined we will never be certain of our measured result.

19. Measurement Definition  Micrometer.0001”  3 readings each end and middle (Total n=9)  Report 9 reading average, minimum reading, and maximum reading

20. Standard Deviation  Sigma  Spread of measurement data

21. Standard Deviation

22. Sample Data Collection  Must be RANDOM  Attempt to represent the entire population  The sample will always be a sample and display less variation than the population

23. Sample and Population  Clock cars in a designated 45mph speed limit zone  6 hours / 1 week = Ave, min, and max  24 hrs / 4 weeks = Ave, min, and max  120 hrs / 26 weeks = Wow!

24. Probe calibration controversy  Define the measurement  Probe 9 points on 1” master sphere: 8 points around equator and 1 point on north pole  3 measurements / 25 days

25. 1” Sphere results  75 reading ave =.999878”  1 Sigma =.000088”  68%.999790” –.999966”  95%.999702 – 1.000054”  99.97%.999614 – 1.000142”

26. The Histogram

27. Use the Histogram

28. Play the Odds

29. CMM game plan  Before we start measuring our parts we can measure the 1” master sphere 3 times and compare our results to our Histogram.  Do we want to order it up?

30. Concentricity of a Perfect Part

31. Define the Measurement  5 point XY Baseplane  12 point Cylinder as Z axis  9 point Circle (bottom) as XY origin and Datum  9 point Circle (top) as feature  3 measurements / 25 days

32. The Histogram

33. Ring gage concentricity  75 reading ave =.00015”  1 Sigma =.00009”  47.5% of the time (or + 2 sigma) it measured worse than.00015” (or as high as.00024”)

34. Another Look !

35. Uncertainty???  Can’t we just??? and then just say…  Dropped parts  Can’t we just ignore gravity????

36. The Myth of “True” Position

39. Define the Measurement

40.  7 point XY Baseplane  5 point X axis line  5 Point Y axis line  XY origin at intersection  9 point circle (Z -.100”)  3 measurements / 25 days

41. Where is the center???  Average.00092”  1 sigma of.00030”  68% of the time our value obtained was between.0006” and.0012” (.0006”)  95% of the time our value obtained was between.0003” and.0015“ (.0012”)

43. .00092”

44. 95%.0003”.0015”

45. References and Acknowledgements  MSA 3rd Edition by AIAG  Mitutoyo of America  Cliff’s Quick Review - Algebra, Statistics, and Geometry  ASME Y14.5-1994 Geometric Dimensioning and Tolerancing  H.E.S. Honda Engineering Specifications  DCC CMM Programming - Part Alignment and Vector Points by Scott Beavers

46. References and Acknowledgements  Technical Shop Math by John G. Anderson  Tooling and Production Magazine  Modern Machine Shop Magazine  Cybermetrics: GAGEtrak software  NWCI Calibration and Inspection  Nelson Precision - A Mitutoyo Company  Qualtech Tool and Engineering  Hower Tool - Ossian, Indiana

47. References and Acknowledgements  NWE/Foxconn - Santa Clara, CA  Mitutoyo of America  SFC (Retired) Thomas J. Ravenell, Ft. Bragg, NC  Dave Schwab - Nelson Precision  Terry Davis - Mitutoyo  Mike Dukehart - Mitutoyo  Jerry Guffy - Mitutoyo  James Vannoy - CMM Technology, Inc.

48. References and Acknowledgements  Scott Beavers - CMM Resources  Travis East - Geometry 2.8 Freeware  Dr. Bill McNeese  Dr. Henrik S. Nielsen  Gordan Skattum  My Wife, Ramona