seymour-hat to do with all that unused color data...john seymour john the math guy, llc john the...
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#COLOR19What to Do with All That
Unused Color Data? John Seymour
John the Math Guy, LLC
John the Math Guy
Color measurements
Process control, direct
Press control, indirect
Press control, indirect
Quality Assurance
ISO 12647-2
Quality Assurance
Quality Assurance
Uses of Color Measurements• Process control• Direct – inline systems• Indirect – plate curves and profiles
• Quality assurance
Numerical Methods for Scientists and Engineers Richard Hamming, 1962
MEASUREMENT
What color measurements
can tell the press operator
Press operator
Danger!! Danger Will Robinson!
Press operator, warning #1My sensors indicate a
color conformance issue is present!
Uses of Color Measurements• Process control• Direct – inline systems• Indirect – plate curves and profiles
• Quality assurance
Press operator, warning #2My sensors indicate a statistical anomaly is
present!
Uses of Color Measurements• Process control• Direct – inline systems• Indirect – plate curves and profiles• Indirect - SPC
• Quality assurance
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Is the process behaving normally?
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Is the process meeting
tolerances?
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Ideal UI for press operator
Nothing bad Nothing funky
Press operator should be …
§Warned of non-conforming product§Warned of odd behavior
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
In tolerance
?
How do we judge this?
When is a job in tolerance?
My customer requires that I keep within 4 DE of
the target color!
When is a job in tolerance?
When is a job in tolerance?
Are 95% below 4 DE?!?
Press operator should be …
§Warned of non-conforming product§ DE is useful, but …§Runtime plot of DE doesn’t cut it§Software should report % conforming
§Warned of odd behavior
Variation type?
In tolerance
?
In tolerance
?
Normal SpecialCause
Fix the process
Yes YesNo No
No worries ? Fix the
equipment
SPC versus QA
Variation type?
Can wejudge thiswith DE?
Color variation
+Targetcolor
Upper control limit
(in DE)
Color probability, Zc values
Color probability, Zc values
Zc = 1Zc = 2
Zc = 5
Likely, but beyond upper control limit
Problems with using DE for SPC
§DE can give a false positive – labelling normal behavior as deviant
Unlikely, but inside upper control limit
Problems with using DE for SPC
§DE can give a false positive – labeling normal behavior as deviant
§DE can give a false negative – labeling deviant behavior as normal
Looking for odd behavior
Finding outliers with DE Finding outliers with Zc
Statistical Process Control of Color, John Seymour, TAGA 2018
Press operator should be …
§Warned of non-conforming product§ DE is useful, but …§Runtime plot of DE doesn’t cut it§Software should report % conforming
§Warned of odd behavior§Runtime plot of DE doesn’t cut it§Software should show a runtime plot of Zc
What color measurements
can tell the trouble shooter
Describing color variation
Describing color variation
Describing color variation
+
Standard deviation ellipse
Diagnosis of source of variation45
Press trouble shooter
§Direction of major axis is the largest source of color variation
Travel
Diagnosis of source of variation47
Diagnosis of source of variation48
Press trouble shooter
§Direction of major axis is the largest source of color variation
§Movement along this axis (travel) can highlight characteristics of variation
What color measurements
can tell the press office
Have I improved the process?
Before After
Is my process in statistical control?
P(Zc)
Zc
Real data Theoretical chi (3)
Data from Company B, C100
?
Will my process meet conformance criteria?
Zc
DE
Questions that Color SPC can answer
§ Is this sample an outlier, or just somewhat unusual?§ What is the major contributor to color variation?§ Did this new piece of equipment or software or change
in process reduce color variation?§ Was this production run under control?§ Can this process reliably meet the color tolerance that
my customer wants?
#COLOR19 John SeymourJohn the Math Guy, LLC
[email protected]://johnthemathguy.blogspot.com/
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John the Math Guy