1. Measurement System
Why do Measurement Systems Commit
Errors?
Why Isn’t a Calibrated Gauge 100%
Accurate?
What are the Sources or Causes of
Measurement Error?
 Environment
Equipment
 Measurement
Operator
Part  Procedure
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2. Measurement System
Equipment
The Equipment i.e. Gauge has design limitations!
The Gauge has display limitations!!
– Digital (Number of Digits Displayed)
The Gauge has Interpretation Limitations!!!
– Dial Read-Out
– Micrometer
– Any Linier Scale
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3. Equipment
LSL USL
0.994
0.995 1.000 1.005
|X| XX |X|
0.996 0.998
0.997 0.999
•When the part’s actual size is different than the gauge’s display
capability. The gauge reports the closest available value. For
these two parts the gauge would report both as 0.998.
•When the actual size is directly between two values the gauge will
report either of the two available values. In this case the gauge would
report either 0.999 or 1.000, or alternate between these two values.
•This means a “Window-of-error” exists between each
available display value. The less repeatable the gauge
the larger the “Window-of-error”.
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4. Operator
Following Proper Procedure to Obtain the
Measurement
Fixture Gauging
Part Cleaning
Location of Measurement
Manual Recording of the Result
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5. Gauge Design & Within Part
Variation
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6. Operator and With-in Part
Variation
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7. Environment
Distraction
Vibration
Lighting
Housekeeping
Work Area
Equipment Cleanliness
Part Contamination
Morale
Leadership
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8. Measurement
Repeatability
Reproducibility
Bias
Linearity
Stability
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9. Measurement Procedure or
Instruction
Well Defined
No Assumptions
Training
Adequate
Enforced
Enforcement
Apathy
Leadership Response
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10. Trials K1 Appraisers K2 K1 = 0.5908
NQS 2
3
0.8862
0.5908
2
3
0.7071
0.5231
K2 = 0.5231
K3 = 0.3146
Part Number: 1233451 Gauge Name: Digital Caliper Date: 2/26/07
Characteristics: Diameter Guage Number: 123 Performed By:
Specification Upper: 1 Units mm Gauge Type: 6" WR Martin
Specification Lower: -1 Units mm
Appraisers = 3 Trials = 3 Parts = 10
From Data Sheet: R-double bar = 0.0034 X-bar diff =0.0016 Range p = 0.0091
% Total Variation (TV)
Measurement Unit Analysis (Preferred)
Repeatability -- Equipment Variation (EV)  R&R = 5.15 Standard
EV = 0.001989 %EV = 55.79% Deviations of the
Reproducibility -- Appriaiser Variation (AV) Repeatability/Reproducibility
AV = 0.00073 %AV = 20.61% Error
Repeatability and Reproducibility (R & R)
 This is Approximately Equal
R & R = 0.00212 Parts
2
K3
0.7071
%R&R = 59.47%
to – 99% Conf.
Part Variation (PV) 3 0.5231
4 0.4467
PV = 0.002866 5 0.4030 %PV = 80.39%
6 0.3742
7 0.3534
Total Variation (TV) 8 0.3375 Number of Distinct Categories (ndc)
9 0.3249
TV = 0.00357 10 0.3146 ndc = 1
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11. Measurement Uncertainty
Window
0.995 1.000 1.005
{
0.996 |X |
0.997
0.998
0.999
 A Given Part Measurement Result Is Displayed By The Gauge as 0.997”
 Given That a Gauge has some Amount of “Error”. What is the “True
Value” of this Part?
 GR&R Value = 1 Standard Deviations of the Measurement System
Error
 Measured Value (X) +&- 2 Standard Deviations give approx 95%
Confidence of the Measurement Uncertainty Window
 The True Value Falls within this Window – 95% of the time
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12. Corrective Action
Study
 MSA
Plan
 What Do I Do Next?
 What Information do I Need to Take the Next Step
Do
 Make and Follow a Plan
Check
 Verify Test Results
Action
 Implement the Corrective Action(s) that are Approved
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13. Problem Analysis
Operator Part Average Comparison
3 Operators - 3 Trials - 10 Parts
1.66
1.655
1.65
1.645
1.64
1.635
1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10
Appraiser A Appraiser B Appriaser C
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14. Problem Analysis
Part Average Operator Overlay
3 Operators - 3 Trials - 10 Parts
1.66
1.655
1.65
Appraiser A
Appraiser B
Appraiser C
1.645
1.64
1.635
1 2 3 4 5 6 7 8 9 10
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15. Problem Analysis
Range Data Operator Range Comparison
UCL Range 3 Operators - 3 Trials - 10 Parts
0.012
0.01
0.008
0.006
0.004
0.002
0
1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10 1 2 3 4 5 6 7 8 9 10
Appraiser A Appraiser B Appriaser C
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16. Problem Analysis
Part Operator Range Overlay
3 Operators - 3 Trials - 10 Parts
0.012
0.01
0.008
Appraiser A
0.006 Appraiser B
Appraiser C
0.004
0.002
0
1 2 3 4 5 6 7 8 9 10
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17. Problem Analysis
Part Comparison by Operator
3 Operators - 3 Trials - 10 Parts
1.665
1.66
1.655
1.65
Appraiser A
Appraiser B
Appraiser C
1.645
1.64
1.635
1.63
1
2
3
4
5
6
7
8
9
0
t1
rt
rt
rt
rt
rt
rt
rt
rt
rt
Pa
Pa
Pa
Pa
Pa
Pa
Pa
Pa
Pa
r
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18. Improvement is
By Choice
Not by Chance?
Reliability
Measurement System
Improvement
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19. Thank You
My Sincere Desire is that Everyone Benefits
from this Brief Presentation
Bill Martin – President
Martin Business Consulting, Inc.
www.MBCIncorp.com
Cell – 931-637-1446
E-mail – Bmartin@MBCIncorp.com
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