New Era Converting Machinery – Gravure Coating Webinar

Gravure Coating:

Webinar – April 26, 2012

John LooserNew Era Converting MachineryP.O. Box 377Hawthorne, NJ 07506Phone: 973-413-4605E-mail: [email protected]

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One of the Most Versatile Methods in the Industry

Webinar Outline• Classic Gravure Coater

– Section Details

• Improvements – Enclosed Applicator– Sleeve System– Cartridge Systems

• Variations– Reverse Gravure– Offset Gravure– Differential Offset Gravure– Process Handles:

• 2-Roll and 3-Roll Gravure

– Pressurized Gravure– Two-side Coating

• Versatility– Application Range– Coating Types– Products

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Classic Gravure Coater

• Sections:

– Coating Reservoir (Pan)

– Gravure Roll (Etched Metal)

– Doctor Blade

– Impression Roll (Rubber)

• Process:

– Coating Pick-up

• Fill Cells

– Wipe (Doctor) Excess

– Transfer Coating

• “Empty” Cells (Transfer Efficiency)

• Film Split

Impression /Back-up Roll

GravureRoll

DoctorBlade

Coating Pan

CoatedWeb

IncomingWeb

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GravureRoll

DoctorBlade

Coating Pan

CoatedWeb

IncomingWeb

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• Terminology:– Direct Gravure

– Forward Application

• Synchronous Rotation

– Pan Fed


• Coating Reservoir– Enclosed Applicator Shown

• Gravure Roll– Motor Driven

– Pneumatically Positioned

• Doctor Blade– Integral to Enclosed Applicator

• Impression Roll– Nip/Web Driven

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Coating Pan

• Function: Delivers Coating to Gravure Roll

• Maintain Constant Level– Stand Pipe or Overflow Weir

• Consistent Coating Movement– Continuous Recirculation

– Foam Management

– Avoid Solids Settling

• Enclosure / Covers– Minimize Solvent Evaporation

– Contain Slinging

• Pneumatic Pan Lift

GravureRoll

DoctorBlade

Supply

ReturnReturn

GravureRoll

DoctorBlade

Supply Return

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Gravure Roll• Function: Deliver Consistent Coating

– Homogeneous Transfer (Across and Down Web)

• Etched / Patterned Cylinder

– Determines Coat Weight and Appearance

– Cell Creation: Mechanical / Laser / Electronic

• Driven Roll

– Tension Control

– Idle Mode

– Vector or Servo Controlled

• Cored for Temperature Control

– Heat Management

– Viscosity Control

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Cell Creation – Gravure Patterns• Cell - Coating Reservoir

– BCM: Volume = Billion Cubic Micron per Square Inch• 2 – 200 BCM

– LPI: Cell Density = Lines Per Inch• 10 – 1500 LPI

– Release / Transfer Rate• % Coating Volume Released Onto Substrate

– Patterns / Shapes• Appearance and Flow

• Promote Release

• Methods for Cell Creation

– Mechanical Engraving

– Laser Engraving

– Electronic Engraving

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Cell Creation – Mechanical Engraving• Roll Design

– Steel Core with Soft Copper Layer

– Chrome Plating Over Pattern

• Cell Creation

– Patterned Tooling Stamps/Forms

Shapes

– Material is NOT Removed• Surface is Re-Formed

– Roll Precision Can Be Affected

• Release Characteristics

– Most Angles are 45o

– High Surface Tension

– Average Release 40-50%

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Mechanical Engraving – Common Shapes

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Quad Roto Flo

Quadragravure

Imp

roving Rele

ase Properties

Pyramid

Roto-Flo Pyramid

Tri-Helical Quad Channel

Cell Creation – Laser Engraving

• Roll Design

– Steel Core with Ceramic Covering

• Cell Creation

– Focused Pulses Create Shape

– Laser Vaporizes Surface Material


– Relatively High Surface Roughness

– Medium Surface Tension


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Multi-Hit Single-Hit

Laser Engraving – Common Shapes

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Imp

roving Rele

ase Properties

30o Channel

60o Hex

Tri-Helical

30o Hex

Cell Creation – Electronic Engraving• Roll Design

– Steel Core with Hard Copper

Layer

– Chrome Plating Over Pattern

• Cell Creation

– Electronically Positioned

Diamond Tip Stylus

– Material is Precisely Removed

– Roll Precision is Maintained


– Low Surface Tension


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Electronic Engraving – Common Shapes

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Doctor Blade• Function: Remove Excess Coating

– Coating in Cells Only

– Cell Determines Coat Weight

• Angle of Attack– Trailing Blade

• Low Speed / Low Viscosity

• Hydraulic Forces Can Lift Blade

• Traps Contaminates

– Reverse Angle / Chisel / Plowing• Increased Speed and Viscosity

• Hydraulic Force Helps Hold Blade

• Rejects Contaminates

• Loading Pressure– 0.5 – 4.0 pli

GravureRoll

Coating Pan

Trailing Blade

25-30o

GravureRoll

Coating Pan

Reverse Angle

30o

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Doctor Blade• Materials

– High Carbon Spring Steel– Stainless Steel– Mylar– UHMW– …………

• Different Shapes– Most Common = Simple Bevel

• Pneumatically Loaded

– On/Off Control

• Angle Adjustment

– Coarse: Trailing and Reverse

– Fine: Attack Angle

• Oscillation

– Motor Driven

Typical Blade Holder

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Impression Roll

• Supports Substrate

– Rubber Covered Roll

– 65-90 Shore A Durometer

• Nip Footprint

– Impression: 0.25” – 0.375”

• Controls Coating Width

– Undercut Roll

– Lift Edges Off Gravure Roll

– Unique Roll for Each Web Width

Web

Gravure Roll

Impression Roll

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Impression Roll

• Impact on Coating Quantity and Quality

– Roll Durometer Impacts Amount of Coating Transferred

• Thick Soft Covering (60-70 duro) = Large Footprint = More Coating

• Thin Hard Covering (80-90 duro) = Small Footprint = Less Coating

– Higher Precision Leads to Better Coating Uniformity

• Soft Roll = .002 - .004” TIR

• Hard Roll = .0005” - .001 TIR

– Thin Precision Coating• Hard Cover – Small Footprint – Precision Roll

Impression Control• Pressure Only

– Pressure in Loading Cylinders Set Impression

– No Position Stops Between Rolls

– Difficult to Control

• Cylinders Lift Roll / Pan / Motor AND Sets Impression

• Pressure Changes Impact Impression

• Adjustable Stops– Cylinders are Utilized for Positioning

– Stop Setting Dictates Impression

– High Loading Pressure = Stability

– Fine / Repeatable Adjustment

• Stop Configurations– Coarse Thread

– Differential Screw

– Taper Wedge Block 20

Improvements

• Enclosed Applicator

• Sleeve System

• Cartridge Systems

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Enclosed Applicator

Supply


CoatedWeb

IncomingWeb

Return

• Enclosed System– No Slinging of Coating

– Minimizes Solvent Evaporation

– Reduced System Volume

• High Rate of Recirculation– Minimizes Air Entrapment

– Foam Control – Flows Out of Chamber

• Easy to Clean– Simple Flushing Systems

– Minimize Waste

GravureRoll

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Enclosed Applicator

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Impression Roll: Sleeve System

• Impression Roll:

– Rubber Covered Sleeve

– Steel Mandrel

• Drive Side

– Cantilever Support

• Operator Side

– Removable Bearing Support

• Quick Width Change

– 5 Minute Task

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Impression Roll: Sleeve System

• Air Pressure Expands Sleeve

– Floats Off Mandrel

• Straight or Tapered Mandrel

• Sleeves

– Nickel

– Composite

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Cartridge System• Base Frame and Drive Stand

Fixed in Web Line

• Gravure Roll, Impression Roll and Coating Applicator on Cartridge

• Quick Change System– Off-Line Clean-up

– Coating Change

– 10 Minute Change-out Time

• Typical Features– Precision Rails Maintain

Alignment

– Quick Connects for Air and Electrical

– Tool-less Quick Disconnect Drive Coupling 26

Cartridge System

• Base Frame with Applicator Roll, Impression Roll and Drive Stand Fixed in Web Line

• Gravure Cartridge Installed

• Five Motors on Drive Stand

• 5-Roll Transfer Coating – Two Rolls on Base

– Three Rolls on Cartridge

• Quick Change System– Switch Between Methods

– Clean-up Off-Line

– 10 Minute Change-out Time

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Variations

• Reverse Gravure• Offset Gravure• Differential Offset Gravure• Pressurized Applicator• Two-Side Coating

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Reverse Gravure

• Reverse Application– Speed Range: 90-120%

• Benefits– Removes Cell Pattern

– Film Split Avoided • Minimizes Ribbing

– Adjust Coat Weight with Roll Speed

• Impression Control is Critical– Light / Controlled Impression

– Precision Required – Better Rolls

• Driven Impression Roll– Suggested for Tension Control

– Overcome Reverse Action


GravureRoll

DoctorBlade

Coating Pan

CoatedWeb

IncomingWeb

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Offset Gravure

• 3-Roll System– Gravure is Offset from Substrate

– Removes Substrate from Coating Nip• Protects Sensitive Substrates

• Roll Rotation– All Roll Same Direction

• Synchronous Rotation

– Two Film Splits

– Thinner Coatings

• Roll Speeds– All Rolls at 100% Line Speed

– Single Drive is Possible• Gravure Roll is Typically Driven – Idle Mode

• Applicator Roll is Nip Driven

• Back-up Roll is Web Driven

SteelBack-up Roll

Gravure“Forward”

DoctorBlade

Coating Pan

CoatedWeb

IncomingWeb

RubberApplicator Roll

“Forward”

FilmSplit

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FilmSplit

Differential Offset Gravure

• 3-Roll System

• Roll Rotation– Gravure: Forward / Reverse

– Applicator: Forward / Reverse

• Roll Speeds– Gravure: Variable

– Applicator: Variable

– Back-Up: Controls Tension

– All Rolls are Driven

• Roll Function– Gravure: Coat Weight Control

– Applicator: Appearance Control

DoctorBlade

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SteelBack-up Roll

GravureFwd / Rev

Coating Pan

CoatedWeb

IncomingWeb

RubberApplicator Roll

Fwd / Rev

FilmSplit

FilmSplit

Differential Offset Gravure

• Cartridge Coater

• All Driven Rolls

– Additional Drives for 5- Roll Coating

• Wide Range of Set-ups

– Gloss Top Coat

• Gravure = 100%, Applicator = 100%

– Silicone Coating

• Gravure = 5%, Applicator = 95%

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Process Handles: 2-Roll GravureCoat Weight and Appearance

• Direct Gravure - Forward Application1. Gravure Roll Selection

2. Gravure / Back-up Roll Nip Footprint

• Direct Gravure – Reverse Application1. Gravure Roll Selection


3. Gravure Roll Direction

4. Gravure Roll Speed

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Process Handles: 3-Roll GravureCoat Weight and Appearance

• Offset Gravure1. Gravure Roll Selection

2. Gravure / Applicator Roll Nip Footprint

3. Applicator / Back-up Roll Nip Footprint

• Differential Offset Gravure1. Gravure Roll Selection


3. Applicator / Back-up Roll Nip Footprint

4. Gravure Roll Direction

5. Gravure Roll Speed

6. Applicator Roll Direction

7. Applicator Roll Speed

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Pressurized Coating Applicator

Pressurized Applicator Tri-Helical Gravure Roll

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Conventional Applicator:No Pressure

Pressurized Applicator:Low Pressure

Pressurized Applicator:Higher Pressure

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Pressurized Applicator

• Adjustable Coat Weight with a Single Cylinder

– 50-100% Weight Increase

– Reduced Gravure Roll Inventory

• Extended Coat Weight Range

– Thicker Coatings

• Constant Coat Weight with Increasing Speed

– More Efficient in Filling Gravure Cells

– Less Recirculation and Foam Generation

• Higher Viscosity and % Solids

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Simultaneous Two-Side Coating

GravureRoll

GravureRoll

• Very Cost Effective– Coat Both Sides at One Coating Station

– Single Dryer vs. Dual Dryers

– Reduced Overall Line Length

• Direct Application (Kiss Coating)– Forward or Reverse Apply

– Coat Weight is Susceptible to Tension Variations

• Limited Range of Applications– Thinner Coatings

– Same / Similar Functional Coatings on Both Sides

Two-Side Coating

• Offset “Kiss” Coat– Unsupported

ApplicatorRoll

GravureRoll

GravureRoll

ApplicatorRoll

• Offset Coat– Supported

ApplicatorRoll

ApplicatorRoll

GravureRoll

GravureRoll

Versatility• Application Range

– Speeds: 0 - 2000+ fpm– Widths: 0 - 200+ inches

• Substrates:– Papers – Boards – Films– Foils– Wovens / Non-wovens– ………

• Coating Types:– Water Based

– Solvent Based

– 100% Solids (UV and E-Beam Cure)

– Hot Melt: Adhesives and Waxes

– ………

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Versatility• Viscosity and Wet Coating Thickness:

– 2-Roll Gravure:• 10-1000 cps

• 0.0005” – 0.0015”

– 3-Roll Gravure• 50 – 2000 cps

• 0.0001” – 0.001”

– Pressurized Gravure• 100 – 5000 cps

• 0.0005” – 0.005”

• Coatings:– PSA’s: Solvent, Aqueous and Hot Melt

– PVDC and other Barrier Coatings

– Primer Coats

– Topcoats: High Gloss and Protective

– Laminating Adhesives

– Silicones: Solvent, Aqueous, 100% Solids

– ……….. 41

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• Top Coats for Wear Resistance on Magazines

• Gloss / Color Snap Coatings for Automotive Brochures

• Adhesives for Wood Grain Patterned Coverings on Furniture

• Gas Emissive Coatings for Medical Packaging

• Protective Coatings on Appliance Overlay

• Optically Clear Adhesives for Protective Window Films

• Silicone Based Release Liners for Medical Bandages

• Pressure Sensitive Adhesives for Medical Bandages

Versatility• Lamination Adhesives for Medical

Drapery

• Primer Coatings for Aluminum Layer in Cigarette Packaging

• Optically Clear Adhesives for Bottle Labels

• Adhesives on Masking Films

• Reactive Coatings on Thermal Papers

• Pre-Paste on Wall Coverings

• Tinting of Decorative Fabrics

• Laminating Adhesives for Lottery Tickets

• Bonding Layer for Foam / Fabric Headliners

Questions?

Thank You!Graphic References• Doctor Blades

– Benton Graphics• Gravure Roll Slides:

– Zecher– Pamarco

• Enclosed Applicator– Harris and Bruno

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John LooserNew Era Converting MachineryP.O. Box 377Hawthorne, NJ 07506Phone: 973-413-4605E-mail: [email protected]

New Era Converting Machinery – Gravure Coating Webinar

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