seymour-hat to do with all that unused color data...john seymour john the math guy, llc john the...

#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

john@johnthemathguy.comhttp://johnthemathguy.blogspot.com/

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John the Math Guy