Standardized Color Management System BYK-Gardner GmbH,
Automotive - Exterior: Surface quality / - Harmony: Uniform Color & Appearance / Gloss Waviness Color Effect Mottling
Automotive - Exterior: Challenges - Various substrates and coating technologies Body vs. Add-on parts - Online/off line painting - / Horizontal vs. Vertical Stable process to guarantee quality over time
Standardized Quality Control Management is needed Different people have different views on what is acceptable: Paint shop <> QC department <> QC Customer <> Supplier <> Weak color memory no statistics possible! - You cannot control what you can t measure! Predictability: What happens if I change something? Reliability: Supplier quality needs to be compared against objective criteria to determine PASS FAIL - Page 4, BYK-Gardner GmbH, BYK-mac Presentation
Effect Coatings 8% of todays automotive finishes are effect coatings 8% Photo: Courtesy of Metallic coatings accentuate the curved profile: Light Dark Flo p - Pearlescent coatings result in a more spectacular color effect: Color Flop : Effect finishes with special glitter effect (Xirallics TM )
Color Systems for Automotive Exterior Applications ΔE* ΔE* CMC ΔE DIN Optimized for effect finishes to guarantee best visual correlation Page 6, BYK-Gardner GmbH, BYK-mac Presentation
CIELAB - System: L*a*b*- Coordinates CIELAB - : L*a*b*- -a* Green L* = +b* Yellow L* = + 58, a* = + 3,4 b* = + 36,6 +a* Red -b* Blue L* =
CIELAB - System: Color Difference ΔL*, Δa*, Δb* CIELAB - : ΔL*, Δa*, Δb* Δ = Sample - Standard Δ L* - + ΔE* Sample ΔL* Δ a* - + Δ b* - + Δb* Standard Δa* ΔE* = (ΔL*) + (Δa*) + (Δb*)
CIELAB - System: L*C*h - Coordinates CIELAB - : L*C*h - -a* 8 L* = C* +b* 9 L* = + 58, C* = + 47,3 h = 5 h +a* -b* 7 L* =
CIELAB - System: Chromatic Non Chromatic CIELAB - : + b* - a* B P Δ H* Δ C* + a* Non-chromatic colors: C* < Use L*a*b* - b* Chromatic colors: C* > Use L*C*h
Limitations of CIELAB System / CIELAB Measured values do not correlate with visual impression All colors within one ellipse are perceived as the same color. Visual : acceptability is based on ellipses not circles: Tolerances for hue are tighter than for chroma Chromatic colors have larger tolerances than pastels or near neutrals : Size and shape of ellipse changes dependent on the hue: Acceptable color differences vary from color to color Green has larger tolerances than dark blue Angular dependency of the acceptance values
Limitations of CIELAB System / CIELAB Measured values do not correlate with visual impression Acceptable color differences for lighter shade colors are larger than for similar darker shades More chromatic colors have larger tolerances than pastels or neutrals
Rectangular versus Elliptical Tolerances ±Δ b* Product Standard Acceptable Match Visually Rejected Match ±Δ a*
Color Systems for Automotive Exterior Applications Improved visual agreement on solids ΔE* Improved visual agreement on solids: ΔE CMC + ΔE 94 Improved visual agreement on metallics: ΔE DIN675-
ΔE CMC Color Measurement Committee of The Society of Dyers and Colorists (UK): 988 Based on visual evaluation of textile samples Currently specified in the following standards: - British Standard BS693 - American AATCC Test Method 73 - ISO International Standard 5-J3 Based on elliptical (not rectangular) spacing and ΔL*C*H* ΔL*C*H* Corrects for chroma, hue and lightness dependent perception
ΔE CMC Color Difference Formula ls L S H cs c Δ E ( ) CMC l : c = Δ L ls L Δ C ab + cs C 3-dimensional ellipsoid with axes corresponding to hue, chroma and lightness 3 Weighting factors (= semi-axis) S L, S C and S H are dependent on color of standard = SL, Sc SH Δ H + S H ab Application factors l and c to modify the lengths of semi-axes I C
ΔE CMC Color Difference Formula decmc (l:c) = ( dl* lsl ) ( ) ( ) dc*ab dh*ab + + csc SH Where S L =.4975 L Sc =.638 C +.638 +.765 L +. C Unless L < 6 when S L =.5 ( ) And S H = S C (Tf + - f) where f = (C ) 4 / (C ) 4 + 9 T =.36 +.4*cos( h + 35) unless h is between 64 and 345 when: T =.56 +.*cos( h + 68) where L, C and h relate to the standard
45 45 ΔE CMC Color Difference Formula / Better correlation to visual perception: Brilliant Yellow with ΔChroma / ΔHue Standard Yellow Yellow -H Yellow -C Yellow +C L* a* b* dl* da* db* dc* dh* 84.5 5.74 96. 84.46 8.88 96.49. 3.4.49.73 84.5 5.75 93.9.7. -.9 -.9 84.37 5.86 99.4.. 3.43.8 de* 3.8.9 3.43 de CMC.64.88. Color Difference: de* -da* Standard; STANDARD 7 L*=84.5; a*=5.74; b*=96 4 3-4 -3 - - 3 4 - - -3-4 +db* -db* +da* +dl* 4 3 - - -3-4 -dl* Color Difference: de CMC -da* Standard; STANDARD 7 L*=84.5; a*=5.74; b*=96 4 3-4 -3 - - 3 4 - - +db* +da* +dl* 4 3 - - Chromatic colors have larger visual tolerances in chroma than in hue -3-4 -db* -3-4 -dl*
ΔE CMC Color Difference Formula / Influence of ratio l : c / L:c Ratio l:c allows for a weighting of lightness to chroma L:c Most common ratio: : Variation in lightness can be double compared to chroma variations C* H* L* C* H* L* ratio : ratio : Page 9, BYK-Gardner GmbH, BYK-mac Presentation
ΔE CMC Color Difference Formula / Influence of ratio l : c / L:c Ratio l : c = : 45 +db* +dl*,5 Ratio l : c = :,5 45 +db* +dl* 4,5 -da* +da* 3 - -,5,5,5 -,5 -,5 - -da* +da* -,5 - -,5,5 - - - -db* -dl* -,5 - ΔE CMC =,84 - -db* -3-4 -dl* ΔE CMC =,46
ΔE CMC Color Difference Formula / Influence of Commercial Factor: cf cf Commercial Factor (cf) determines the overall size of the ellipse (cf) cf sets the color tolerance: ΔE CMC < cf PASS cf ΔE CMC > cf FAIL C* H* C* H* L* cf=. L* cf=.5 Page, BYK-Gardner GmbH, BYK-mac Presentation
ΔE CMC Color Difference Formula / Influence of Commercial Factor: cf 45 +db* +dl* 4 45 +db* +dl*,5,5,5 3,5,5,5 -da* +da* -da* +da* - -,5 - -,5,5,5 - -,5 - -,5,5,5 -,5 -,5 -,5 - - - - - -,5 -,5 -,5-3 - - - -4 -db* -dl* -db* -dl* cf =. cf =.5 45 +db* +dl* 4,5 3,5 -da* +da* - -,5 - -,5,5,5 -,5 - - - -,5-3 - -db* -4 -dl* cf =.5
ΔE CMC Color Difference Formula / Summary One tolerance for all colors: cf = size of the tolerance ellipse cf = Tolerance is based on elliptical spacing Size and shape of tolerance ellipse is calculated based on Standard location in the color space
ΔE CMC Color Difference Formula / Summary Better correlation to visual perception: Chromatic Colors: Larger visual tolerance ellipse ΔE CMC smaller for chromatic colors than for achromatic colors (ΔC* and ΔH* are weighted less) compared to Δ E* Δ E* ΔE CMC ΔC* ΔH* Light Colors: Larger visual tolerance ellipse for lightness ΔE CMC smaller for light colors than for dark colors (ΔL* is weighted less) compared to Δ E* Δ E* ΔE CMC (ΔL* ) Visual acceptability is decreasing from Hue Chroma Lightness l:c:h = :: l:c:h = ::
ΔE CMC - Typical Tolerances Achromatic + Chromatic + l c cf -5 5 Metallics 5 45 75 45.5 Solids
ΔE 94 - Color Difference Formula: 995 Based on visual evaluation of new sample sets solid colors only - Currently published in the following CIE recommendation: - CIE Technical Report 6: Industrial Colour Difference Evaluation CIE - CIE Based on elliptical spacing and ΔL*C*H* ΔL*C*H* Corrects only for chroma dependent perception
ΔE 94 - Color Difference Formula / de 94 = ( ) dl* k L SL ( ) ( ) dc*ab dh*ab + + k C SC k H SH S L = S C = +.45 C* ab S H = +.5 C* ab k L = k C = k H = Weighting factors S C and S H are dependent on chroma of standard Application factors k L, k C, k H are used to correct for variations in reference conditions: - Illumination: D65 - Illumination intensity: lx - Background field: neutral grey - Viewing field: > 4 - Sample: uniform color - direct contact color difference - 5 CIELAB units
ΔE CMC and ΔE 94 Color Difference Formula/ Limitations Tolerance is based on ΔL*C*H* ΔL*C*H* Color change due to viewing angle is not part of the calculation
DIN 675- Part : Tolerances for Automotive Paints - DIN 675- Part : - Developed Collaboratively by European OEM s: Used by VW, Audi, BMW, Mercedes, General Motors OEM : VW, Audi, BMW, Mercedes, General Motors Based on visual evaluation of metallic samples Good visual correlation Uses weighting functions dependent on color of standard Uses application factors to differentiate between different requirements (= g-factors): Batch approval Production: car body + add-on parts, repair line (=g- ) : +, ΔE DIN675-
DIN 675- Part : Tolerances for Automotive Paints - DIN 675- Part : - Non-chromatic: = = + = 7. 7. 5. 3 5. γ b a L S S L S γ γ * * * ' + + = γ γ γ γ γ b b a a L L S g Δb S g Δa S g ΔL ΔE γ γ Chromatic: + + = + = + = γ γ γ γ γ γ. 4. 7. ; 7. max 4 35 48 max 7 5. 3 5. L C S L γ. C γ.. ; S L S γ γ γ H C L * * * ' + + = γ γ γ γ γ H H C C L L S g ΔH S g ΔC γ g S ΔL ΔE γ
DIN 675- Part : Chromatic Non Chromatic DIN 675- Part : C 8 or C and L < 7 Samples can differ from angle to angle Master panel and samples can differ L * 7 non-chromatic chromatic Combined effective color difference: : ΔE eff (γ) = σ(γ) ΔE ab (γ) + ( - σ(γ)) ΔE CH (γ) σ = f (C*; L*) 8 C * Achromatic: σ = Chromatic: σ =
DIN 675- Part : Typical Tolerances DIN 675- Part : Application Factors Tolerance g L g a g b g C g H ΔE eff Paint Batch Approval...... ΔE C Paint Line Body....8.. ΔE P Repair Line....8..5 ΔE P Repair Line with gap....8. 3. ΔE P
Companies using similar approach as DIN 675 Part DIN 675 Part Global specification Global specification US Plant in Georgia Global specification
Similar Approach as DIN 675 Part D675-Part Weighting Factors S S Application Factors g g Color Difference ΔE Tolerance Batch Approval Tolerance Production DIN 675 - Calculated based on color values of standard Batch Approval / / / / Production: /. /. /.8 /. Always combined calculation ΔE ab + ΔE CH..4..4 degm Calculated based on color values of standard = DIN 675 - =DIN675- Same as DIN 675 - DIN 675- Either ΔE ab or ΔE CH Angle dependent ΔSE = delta Color and Effect ΔSE = delta Color and Effect
BYK-mac Total Color Difference analysis BYK-mac ΔE total = ΔEp5 + + + ΔEp5 ΔEp45 ΔEp75 ΔEp 5 + ΔS 5 + ΔS 45 + ΔS 75 + ΔG ΔS total = 4 ΔSE = ΔE total + ΔS total
New BYK-mac Multi-angle Color and Flake Characterization Multi-angle Color Measurement Illumination: 45 Detection: 6-angles 6-5, 5, 5, 45, 75, Sparkle Characterization Direct illumination: 5,75,45 from perpendicular Camera detection: Graininess Characterization Diffused illumination Camera detection: Page 36, BYK-Gardner GmbH, BYK-mac Presentation
Principles of Color Management System Figures and Facts instead of feelings One binding reference Binding and realistic tolerances
New smart-chart Software smart-chart Complete solution: BYK-mac wave-scan cloud-runner Comprehensive Standard Management General & customer specific color, appearance, mottling scales & Definition of tolerances and limits Standardized measurement procedure: Organizer Easy to use Data Analysis Traffic light function in QC reports QC Test Report: Single Vehicle Harmony Process control charts: Scorecard Trend Charts -
NEW smart-chart Software for BYK-mac, wave-scan Family, cloud-runner
smart-chart Software: Standard Management / Set Color difference method: dec -- dep dec -- dep Set geometries Define color families with common settings: ΔE equation, geometry, statistic DE,, Define tolerances and limits
smart-chart Software: Standard Management / Set effect geometries Define effect tolerances / limits /
Color Measurement in Practice: Standard Management Define the Master Production QC QC Add-on parts
Color Measurement in Practice Alternative : Distribution of Working Masters Design Master Visually accepted working masters Measured with individual instruments
Color Measurement in Practice Alternative : Distribution of Working Masters Design Master Production of working Standards Working Standards for plants & suppliers Limitations: Working standards differ from each other Inter-instrument agreement: Excellent with BYK-mac due to LED technology LED BYK-mac
Color Measurement in Practice Alternative : Physical Master-Master Panel + b* All plants and suppliers use the same master-master. - a* + a* - b*
Color Measurement in Practice: Standard Management How is the Master-Master determined? Master-Master is the panel closest to the average of all measured paint masters (~ ).5.5 - -.5.5 -.5 - -.5 Each plant and supplier must measure master-master of each color with individual instrument Future color difference measurements are based on one common reference value
Color Measurement in Practice: Standard Management Alternative : Physical Master-Master Panel Design Master Production of Working Standards Master Master standard is determined Master Master is measured with every BYK-mac BYK-mac Working Standards for visual control Limitations: Working standards differ from each other Inter-instrument agreement Global supply chain
Color Measurement in Practice: Standard Management Alternative 3: Digital Standard with BYK-mac 3 BYK-mac Design Master Production of Working Standards No more limitations: One global reference Master Master standard is determined Master Master is measured with Master BYK-mac BYK-mac Working Standards for visual control Digital Master is emailed to supply chain
BYK-mac makes Digital Master possible BYK-mac Excellent inter-instrument agreement Test performed manually Operator Influence - 4 Colors 4 6 panels/color w/ 6 readings/panel 6 6 BYK-mac BYK-mac 5 L * green beige black metallic white yellow green bright silver bright red solid blue dark red steel gray metallic dark silver green yellow yellow blue violet metallic
BYK-mac inter-instrument agreement BYK-mac Delta Delta comparison: 5 and 5 angle - 5 5 Δ - BYK-mac- Δ BYK-mac Δ BYK-mac - Δ BYK-mac ΔL*,5,5-5 -3 - -,5 3 5 - -,5 - Δ BYK-mac,5,5-5 -3 - -,5 3 5 - -,5 - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δa*,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δb*,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac 5 5
BYK-mac inter-instrument agreement BYK-mac Delta Delta comparison: 45 angle - 45 Δ BYK-mac - Δ BYK-mac ΔL*,5,5-5 -3 - -,5 3 5 - -,5 - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δa*,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δb*,8 45,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac
BYK-mac inter-instrument agreement BYK-mac Delta Delta comparison: 75 and angle - 75 Δ BYK-mac - Δ BYK-mac Δ BYK-mac - Δ BYK-mac ΔL*,5,5-5 -3 - -,5 3 5 - -,5 - Δ BYK-mac,5,5-5 -3 - -,5 3 5 - -,5 - Δ BYK-mac Δ BYK-mac - ΔBYK-mac Δ BYK-mac - Δ BYK-mac Δa*,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δ BYK-mac - Δ BYK-mac Δb*,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac,8,6,4, -,5 -,5 -,5 -,,5,5,5 -,4 -,6 -,8 - Δ BYK-mac 75
smart-chart Software: Digital Standard smart-chart Key for standardized color managment
smart-chart Software: Standard Management for wave-scan smart-chart Define scales to be displayed Define limits for Pass / Fail /
NEW smart-chart Software for BYK-mac, wave-scan Family, cloud-runner
smart-chart Software: Organizer/ Clear sample identification: Par : Models Par : Colors Par 3: Paint Booths
smart-chart Software: Organizer for BYK-mac smart-chart BYK-mac Menu guided operation: Car schematics help to define sampling procedure
smart-chart Software: Organizer for BYK-mac Example: Color Harmony test procedure Checkzone creation Curvature per checkzone Number of readings per checkzone Definition of Panel Matches Measurement Direction
BYK-mac Reliable Operation and Handling Stable positioning due to 4 trigger pins on bottom plate 4 Sensitivity of pins can be adjusted to sample curvature Symbol Sample Curvature Example I Flat Test Panel 4 Pins <. mm ) Low curvature Hood 3 Pins <. mm; Pin <.3 mm O Medium curvature Bumper 3 Pins <.3 mm; Pin <.9 mm o High curvature Mirror Housing 3 Pins <.6 mm; Pin off Off Pins deactivated, but it is ensured that no ambient light will enter aperture Curvature > 5 mm >5mm Measurement of sample temperature
Color Measurement in Practice Reproducible Production QC Defined measurement areas and measurement direction 6 5 7 4 8 3 Direction of instrument illumination
smart-chart Software: Organizer for wave-scan Checkzone creation Scan length per checkzone Number of readings per checkzone Definition of Groups
NEW smart-chart Software for BYK-mac, wave-scan Family, cloud-runner 3 4
smart-chart Software: Data Analysis - List - Filter database by: Status Date Model Color Paintline Instrument - - - - - Click on Refresh
smart-chart Software: Data Analysis Test Report - Single Vehicle Harmony Data Table Match to standard with Pass/Fail / Panel match with Pass/ Fail analysis /
smart-chart Software: Data Analysis Test Report - Single Vehicle Harmony Chart Page 66 - Seminar Material
smart-chart Software: Data Analysis Scorecard - Management Summary Page 67 - Seminar Material
smart-chart Software: Data Analysis Trend - Production / Batch Process Control / Page 68 - Seminar Material
smart-chart Software: Data Analysis Trend Comparison - Production vs Batch or Body vs Add-on Parts Page 69 - Seminar Material
NEW smart-chart Software Standardized QC management system
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