Developments in on-line Gauging of Complex Extrusion Coating – An update
Stefan SchönebergerSession 10.4 /7629
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Presentation Overview• Introduction• Complex extrusion coating process• Optimum sensor requirements• Overview of available sensor technologies• Comparison of various sensor technologies• Best choice of optimum sensor technology: HR-FSIR• Process Control; Process Tools; Process Visualization• Conclusion: Techno-Economic Benefits
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Introduction• Rapid growth globally in complex web coating lines
• Aseptic packaging of liquid consumables– Multilayer product for barrier properties & long shelf-life– attractive packaging for consumer attention
• Highly competitive Marketplace with rising raw material costs & tightening margins
• Large capital investments in high-speed complex extrusion coating laminators
• Increasing requirements for on-line gauging
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Complex Extrusion Coating Process• Product structure
– Printed paperboard substrate or metallized film laminated substrate
– Mono layer extrusion (outside layer, tie layer)– Multilayer co-extruded barrier coatings – Lamination: Aluminum Foil or Blown Film
• Process– Extrusion Coater/Laminator– Multi coating stations (outside layer, tie-layer, inside
layers)– High speed production process
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Optimum Sensor Requirements
Ability to: • Measure true absolute thickness/basis weight of
coatings of varying densities on different substrates.
• Provide non-contacting measurement with low noise and fast response.
• Provide high performance dynamic measurement of coatings independent of substrate variations in a high-speed production environment.
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Overview of on-line sensor technologiesMajor categories of on-line sensor technologies for
complex Extrusion Coating Process are:
• Nuclear Sensors
• X-Ray Sensors
• Full Spectrum InfraRed Sensor (High Resolution FSIR) based on Absorbance Mode (SpectraBeam)
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Nuclear Sensors
• Based on Beta or Gamma Radiation; Subject to source decay: (PM-147;KR-85;SR-90:AM-241)
• Radioactive; hence requires licensing for use and disposal
• Measure Basis weight (Not thickness)• Cannot discriminate between layers in multilayer
coatings• Use subtractive measurements for coat weight• Use synchronized same-spot • Use substrate-independent calibration technique (True
Net Coat Algorithm)
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X-Ray Sensors• No licensing required.• Not subject to regulations for use at strengths below 30
keV• Measure Basis weight (Not thickness)• Cannot discriminate between layers in multilayer
coatings• Composition sensitive• Use subtractive measurements for coat weight• Use synchronized same-spot • Use substrate-independent calibration technique (True
Net Coat Algorithm)
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X-Ray & Nuclear Sensor Measurement• Both X-Ray and Beta Ray Gauges Are Total Mass Gauges
• Particles will be absorbed by all mass between source and receiver
• Must pay attention to dimensional (z) and air mass changes
Nuclear Gauge
Output Signal
Web
Pm-147 or Kr-85Source Capsule
IonizationChamber
All Mass isMeasured
Web
X-Ray Gauge
Output Signal
IsotopeOr X-Ray Tube
IonizationChamber
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High Resolution FSIR Sensors• Non-radioactive• IR measurement based on absorbance• Full spectrum analysis using Chemo-metrics effectively
eliminates or minimizes sensitivity to additives, printing etc.
• Insensitive to web or air temperature• Is an on-line spectrometer• Elliptical geometry of 6 x 25 mm design allows
measurements closer to web edge, resulting in enhanced streak-detection capability and better edge control and potential less edge trims.
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Physics Behind IR Measurement - General
Each Material Has Unique Absorption Pattern
Stronger
Weaker
Absorption is StrongerAt Certain Wavelengths
Compared to Others
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SpectraBeam FSIR Sensor
Optics
Optics
Web
MSP
Tuning Fork
Lamp
Filter Matrix
FixedDetector Array
Full Absorption Spectrum
Only Mass or Thickness of
Polymer is Measured
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SpectraBeam Sensor
Signal
Absorption
Intensity
Lamp Response
Material "Signature"
Full Spectrum Array
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Chemo-metric Analysis
Full Spectrum Array Accurate Calibration forCoatings on various substrates
(Pigmented or Printed)
Chemo-metricAnalysis
&Pattern Recognition
Software
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Chemo-metric Analysis
MeasuredStandardized
Spectrum
Composition #1
Composition #2
Effect #1(TiO2)
Effect #2(surface)
Residual
Absorption
Eliminates errors caused by Surface Finish, Colorants and other Additives
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Measurement Technology ComparisonCriteria SpectrabeamFSIR X-Ray Beta
Noise Characteristics Good Good Nuclear Statistics
Noise degradation over time
None None source decay
Tolerance to Web Flutter Best (+/- 5 mm) Good(+/- 3 mm) Fair (+/- 1 mm)
Temperature Sensitivity No Yes Yes
X,Y,Z Sensitivity No Yes Yes
Composition Sensitivity No Yes Some
Dynamic Repeatability Best Good Good
Multilayer CoatingCalibration Complexity Moderate High High
Polymer Discrimination Possible No No
Multi-Component Measurement
Yes No No
Exact same- spot Yes No No
Substrate effect Minimum Yes Some
Printing,Additive Effects
Minimum Yes Yes
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Best Choice of Optimum Sensor Technology
Based on the comparative studies of various available technologies as discussed in this presentation:
High-Resolution Full Spectrum InfraRed Sensor (on-line Spectrometer) offers the best choice for the accurate dynamic measurement of multilayer coatings in complex Extrusion Coating Applications.
Reflectance HR-FSIR configuration is ideal for measurements of outside layer on paper/board or metallized film laminated substrate and co-extruded inside layers on foil.
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Process Control
• Auto Profile Control (APC) with Accelerated Thermal Response (ATR) feature helps reduce CD Variations
• MD Control helps reduce Long Term Machine Direction variations
• Yield Optimization Control: Target Management Control (TMC) Helps in Polymer Material Savings
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Process Analytical Tool• Fast Fourier Transform (FFT)
Helps in reducing short term machine direction variations caused by extrusion/laminator equipment
• Edge Zoom based on extended data
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Process Visualization
• Contourview Display Suite- Contour View Display (3 Dimensional)- Blanket View Display (Topographical)
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Techno-Economic Benefits
• Customer Results - Multiple case studies in Complex Extrusion Coating Applications:
- Reduction in CD variations: 50 to 90%, typically 70% in 20 minutes from startup
- Faster product change-over, typical reduction by 67%
- Scrap reduction (start-ups,edge & sampling scraps): 50%
- Increased edge measurement and control: Additional 2% of width
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Conclusion
• Computer-based on-line gauging systems with optimal sensor technologies, advanced process control & process analytical tools is a powerful Process Management Tool for complex Extrusion/Laminating Processors.
Thank you for your attention.
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