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1.0 What is Web Handling Introduc7on and Overview
Timothy J. Walker, TJWalker + Associates Inc. 1620 Edgcumbe Road, Saint Paul, MN 55116
[email protected] www.webhandling.com 651.686.5400
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What is Web Handling?
Ø The process technology of transporOng and storing thin, flexible materials.
Ø A web is any flexible, conOnuous material where:
Length >> Width >> Thickness
Ø Webs include papers, films, foils, non-‐wovens, texOles, and laminates.
Thickness Width Length
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Web Handling Processes
Makers: Coa7ng, Extrusion, & Paper and Film-‐Making
Converters: SliOng, Die-‐CuOng, & Lamina7ng
Controls! Cri7cal to successful web
handling.
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Web Handing Technology Areas
1: Introduc7on to Webs and Web Handling
2: Tensioning
3: Rollers and Trac7on
4: Nipping and Lamina7on
5: Lateral Control
6: Winding
7: WH Resources
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Web ProperOes of Tensioning
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WH Fundamentals
Web ProperOes of Tensioning
The Secret to Web Handling
1: Introduc7on to Webs and Web Handling
TJWA Inc., Copyright 2011 www.webhandling.com 0-‐5
+ Web Proper7es ü What material proper7es does a web handler need to know? ü Know your web’s mechanical and fric7onal proper7es.
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Tension Control Systems
Tensioning Elements
MD Tension Profile
2: Tensioning
WH Fundamentals
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+ Tension Control ü What is the right tension for your web or process? ü What controls tension in your process? ü What determines the op7mum number of tension zones?
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3: Rollers & Trac7on
WH Fundamentals
TJWA Inc., Copyright 2011 www.webhandling.com
Roller Basics Alignment TracOon
+ Rollers and Trac7on ü Design rollers for driving, idling, and nipping applica7ons ü Why is roller parallelism important? ü Understand when webs slip on rollers.
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WH Fundamentals
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Nipped Roller Systems
4: Nipping & Lamina7on
LaminaOon
+ Nipping and Lamina7on ü What is the load and pressure in a nip? ü What causes or reduced pressure varia7ons? ü What are the best prac7ces of lamina7on?
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WH Fundamentals
Guiding Wrinkling Spreading
5: Lateral Mo7on: Tracking, Wrinkling, Spreading, Guiding
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Tracking
+ Lateral Mo7on ü What cause a web to shib laterally? ü What web guide is best for a process? ü What causes web wrinkles? ü What eliminates wrinkles?
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WH Fundamentals
6: Winding: Process, Roll Quality, Equipment Design
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Winder Design
Roll Quality
Winding Process
+ Winding, Rolls, Winders ü What winder design is best for a product? ü What determines the pressure inside a wound roll? ü What causes roll and web defects?
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WH Fundamentals
7: Web Handling Resources
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+ Resources ü Where can I learn more about web handling? ü Where can I get help with web handling?
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Web Handling and Winding Common Problem Areas
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Tension VariaOons
Web Buckling
1. Tensioning 2. Imperfect Webs 3. Nipping Roller Systems 4. MD and TD Control 5. Web Buckling
Imperfect Webs
MD and TD Control
Nipped Roller Systems
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Part 1: Solu7ons w/ Web Tensioning
Machine Direc7on
Tension: MD VariaOons
Tension: Too High or Too Low
Tension: TD VariaOons
Transverse Direc7on TD =
MD =
Tension: Varies Over
Time Tension:
Slit Strands
1A 1B 1E
1D
1C
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Part 2: Solu7ons with Imperfect Webs
Baggy Webs
Cambered Webs
Cambered and Baggy Webs
Curled Webs
Non-‐Flat Webs
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Part 3: Solu7ons to Nipping Varia7ons
Nipped System Design LaminaOon
Nip Varia7ons Nip Design
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Part 4: Solu7ons with Control
MD Slip on Rollers
MD Slip Between Web and Driven or
Idler Rollers MD Slip in Rolls
MD Slip Between Layers in a Rolls
TD Slip/Shi` on Rollers
TD Error in Rolls
Web TD Shibs or Slips Laterally on
Rollers
TD Shib or Misalignment of Layers in a Rolls
Machine Direc7on Control
Transverse Direc7on Control
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Part 5: Solu7ons with Buckled Webs
In Spans
Buckled Between Rollers
Buckled Web in Spans
MD Buckles On Rollers
TD Buckles On Rollers
On Rollers
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In Rolls
MD Buckles Rolls
TD Buckles in Rolls
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Ques7ons } What do you want to learn? } What ques7ons do you have? } What materials are you working with? } What processes are you working with? } What are your top sources of waste related to web handling? } What would you like to share from your experience?
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1.1 -‐ Web Proper7es What makes one web different from another?
Timothy J. Walker, TJWalker + Associates Inc. 1620 Edgcumbe Road, Saint Paul, MN 55116
[email protected] www.webhandling.com 651.686.5400
TJWalker + Associates Inc. www.webhandling.com 18
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Web Proper7es WHAT IS IT What webs are difficult?
• Extremes of thickness Ultra-‐thin (less than 0.5 mil or 12 microns) Ultra-‐thick (unable to bend around a roller)
• Extremes of width Ultra-‐narrow (less than 0.2-‐in or 5mm) Ultra-‐wide (over 100-‐in or 2.5m)
• Extremes of elasOcity Ultra-‐s7ff (steel) Ultra-‐stretchy (polyurethane, some nonwovens, elas7cs) Visco-‐elas7c and non-‐elas7c
• Easily damaged Easy to tear, break, crush, deform, scratch
• Difficult surface properOes Slippery, tacky, fric7onal proper7es varying as a func7on of pressure
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Web Proper7es WHAT IS IT What processes are difficult?
• Fast (above 1000 fpm) • Ultra-‐precise (registra7ons below 3-‐5 mils, 75-‐125 microns) • Process with drama7c mechanical property changes (paper-‐making, film-‐
making/orienta7on, extrusion coa7ng on films) • Long air flota7on ovens • Webs in vacuum • Webs in liquids • Speed or length transi7ons (accelera7on, accumula7on/dispensing, turret
winders) • Ultra-‐long processes (over 300m web path) • Extreme tension transi7ons, esp. to and from zero tension • Lamina7ng greatly dissimilar mechanical proper7es curl free, esp.
anisotropic to isotropic webs • Machine direc7on registra7on
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WH Technology HARDWARE/SOFTWARE What analogies or images are helpful? Webs are like springs:
• Most webs respond elas7cally to force or need force to elongate Webs are like ropes:
• Webs bend easily (except widthwise) • Webs don’t support compression (easily buckling) • Webs work well under tension (they are s7ffer and straighter)
Webs are like beams: • They have a cross-‐sec7on area • Think of load in term of stress (force/area) • Bending force is func7on of bh3/12, un7l buckling • Bending force is func7on of 1/L3, un7l buckling
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What is Your Web? Webatronium?
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} Thickness, Width } Stress or Strain to Yield or Break } Young’s Modulus of Elas7city } Surface Characteris7cs (Fric7on, Roughness, Porosity) } Visco-‐Elas7city? } Poisson’s Ra7o? } Anisotropy? (MD-‐TD Differences) } Layers? Laminate? Coated?
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What is the right tension?
The Right Tension Qs
The answer to this requires understanding of:
force, tension, stress, strain,
tensile-‐elonga7on tes7ng, yield point, break point,
& modulus of elas7city.
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Web Handling Stress
εσΔ
Δ=E
ducOle break σ
stress
strain, ε
(force/area)
x x brifle break
yield point
elasOc strain
(%)
Typical web handling tensions are 10 to 20% of a web’s yield or break stress.
Tension setpoint should be 10-‐20% of yield or break point.
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Common Units & Variables
TJWalker + Associates Inc., Copyright 2011
www.webhandling.com SWHP1-‐25
t = web thickness, mils or inches, 0.001” = 25µm w = web width, inches, 1” = 25.4mm L = length, inches, 1” = 25.4mm V = web or roller speed, feet/min. (fpm), 100 fpm = 30 m/min D = diameter r = radius FT = Force of tension, lbs, 1 lbs = 0.454 kg T = tension force per width, pli, 1 pli = 175 N/m
(pli = Pounds / Lineal Inch of width) σ = web stress, psi, 1 psi = 6.9 kPa ε = web strain, dimensionless E = Young’s modulus, psi, 100,000 psi = 690 MPa θ = wrap angle, degrees or radians
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Tension Units (SI)
FT Tension Force
Force lbs (kgf or N)
T Tension
Force per Width pli (kgf/m)
FT = 10 kgf FT ~ 100 N
FT = 10 kgf w = 0.5 m T = 20 kgf/m T ~ 200 N/m
FT
FT w, width wFT T=
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Tension Units (English)
FT Tension Force
Force lbs
T Tension
Force per Width pli
FT = 10 lbs FT = 10 lbs w = 10 in. T = 1 lbs/in T = 1 pli
FT
FT w, width
FT
FT
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What tension will break or deform a web?
The Right Tension Qs
What is stress? What is strain?
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Tension Units (SI)
twF
=σ
FT Tension Force
Force lbs (kgf or N)
T Tension
Force per Width pli (kgf/m)
σT Tensile Stress Force per Area lbs/in2 (kPa)
FT = 10 kgf FT ~ 100 N
FT = 10 kgf w = 0.5 m T = 20 kgf/m T ~ 200 N/m
FT = 100 N w = 1 m t = 25 µm σT = 4 MPa
w
t, thickness FT
FT w, width wFT T=
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Tension Units (English)
FT Tension Force
Force lbs
T Tension
Force per Width pli
σT Tensile Stress Force per Area
lbs/in2
FT = 10 lbs FT = 10 lbs w = 10 in. T = 1 lbs/in T = 1 pli
FT = 10 lbs w = 10 in t = 0.001 in σT = 1000 psi
w
t, thickness FT
FT w, width
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KEY CONCEPT
Stress Stress and pressure are both defined in units of force per areas. To berer understand any web process, convert forces into stresses by dividing the load by the cross-‐sec7onal area it is exerted over.
Use: Machine tension is commonly measured as a force in units of lbf, kgf, or N. To compare different products or processes, calculate tensile stress by dividing tension force by product thickness and width.
Example: FT = 50 lbf creates higher stress as cross-‐sec7onal area decreases. For w=50” and t=0.010”, the tensile stress is a low 100 psi. For w=50” and t=0.001”, the stress is 1000 psi. For w=1” and t=0.001”, the stress is 50,000 psi!
!
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Strain Defined
00
01
LL
LLL Δ
=−
=ε
L0 = Dimension of zero tension web
L0
L1
L1 = Dimension of tensioned web
ΔL
Strain, ε, is the ra7o of the change in a dimension over the untensioned dimension. For tensioning, strain is the change in length over the untensioned length.
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KEY CONCEPT
Strain Strain is dimensional change in a solid material in reac7on to stress. For posi7ve stresses, materials will elongate in the direc7on of the stress. For nega7ve stress or pressure, materials will compress. Strain is calculated as the change in dimension divided by the original dimension.
Use: When a web is forced to conform around varia7ons in roller parallelism or diameter, the web’s response will begin by determining the web strain. Example: If a roller diameter varies from 5.00” to 5.05”, the web develop a 1% strain differen7al to conform to roller.
!
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Tensile-‐Elonga7on Tes7ng
Tension or
Force
%ElongaOon
Most tensile-‐elonga7on tes7ng focuses on measuring ul7mate break strength or elonga7on, but should provide other mechanical proper7es.
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Images courtesy of Instron
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Tensile Elonga7on Tes7ng Yielding (2) is a permanent, non-‐elas7c dimensional change.
Each material has a characteris7c stress and strain where yield begins – called the yield point.
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Break with brifle fracture
Break with ducOle fracture
Web handling systems are designed to avoid reaching a material’s
yield point.
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Break Point
The break point is the ul7mate, catastrophic end to high elonga7ons or high stresses.
Brirle materials have lirle yielding prior to breakage. Duc7le materials will have significant yielding prior to the break point.
σstress
strain, ε
Force Area
Break with brifle fracture
(%)
Break with ducOle fracture
X
X
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The ‘magic’ tension is 1 lb/in or 1 PLI.
Typical Tensions
80-‐90% of processes run between 0.3 and 3.0 PLI
95-‐98% of processes run between 0.1 and 10.0 PLI
175 N/m or 18 kgf/m
50 N/m or 500 N/m
17 N/m or 1750 N/m TJWA Inc., Copyright 2012 www.webhandling.com 37
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Web Handling Stress
εσΔ
Δ=E
ducOle break σ
stress
strain, ε
(force/area)
x x brifle break
yield point
elasOc strain
(%)
Typical web handling tensions are 10 to 20% of a web’s yield or break stress.
Tension setpoint should be 10-‐20% of yield or break point.
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Why is a 5:1 or 10:1 tension safety factor needed?
Tension, Strain,… Qs
Tensioning systems control average tension.
Web and equipment imperfec7ons can create larger MD and TD
varia7ons from average tension.
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Visualizing Tension Varia7ons
+30 -‐20
+20 -‐5
+20
72
A thermostat will indicate the temperature at one point, but the temperature will vary from point-‐to-‐point within the house.
40lbs 1PLI
80lbs 2PLI 70lbs
0PLI
1.5PLI 0.2PLI
1.8PLI
A load cell or dancer roller will control or indicate the tension at one point in a process, but the tension will vary through the process, both MD and TD.
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Sources of MD and TD Tension Varia7ons
Baggy Web
T
width
T
width
Misalignment Drag and Iner7a
T
MD
T
width
Diameter Varia7ons
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From data given in the next few slides, what would be the right tension for PET, PP?
How about at elevated temperatures?
The Right Tension Qs
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Some Proper7es of PET
From DuPont Teijin Films Mylar® Data Sheet
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Yield Stress and Temperature Stress
-‐-‐-‐-‐-‐-‐-‐-‐-‐
Stress -‐-‐-‐-‐-‐-‐-‐-‐-‐
From DuPont Teijin Films Mylar® Data Sheet
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Measuring Modulus
twF
=σStress, p
si
Strain,%
F
L
dL
Calculate modulus by noOng the length change of a strip under a
known weight (tension).
LLδ
ε =
( )twLFLEδδε
δσ==
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Modulus is Important
It is quite common to find quality labs measuring break or yield points, but
never calcula7ng modulus.
Knowing modulus is quite useful in web handling and
cri7cal to lamina7ng.
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Modulus? We Don’t Do Modulus!
Force, lbs
Strain,%
Quality labs commonly have tensile elonga7on testers for break, peal , or tear tes7ng, but when asked to measure
modulus, 1) have never done it, 2) don’t know how to, and 3) find no help in the equipment manual...
= very frustrated web handler.
Output Data
Unshared Data!
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Modulus Defined
DucOle Break σStress
Strain, ε
(psi)
x x
Ε=Δσ/Δε
Brifle Break Yield Point
ElasOc strain
(%)
Modulus is the ini7al slope the stress-‐strain curve. It describes a web’s “stretch-‐ability.”
σ
ε
High modulus: Foils
Papers Polyester
BOPP HDPE
PE, Vinyl, PU
Low modulus:
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Using Elas7c Modulus
The elas7c modulus is a material property that describes the rela7onship of stress to strain.
εσΔ
Δ=E
σstress
strain, ε
(force/area)
(%)
Eεσ =
Eσ
ε =
ε = 0.01 = 1% E = 500,000 psi σ = εE = (0.01)(500000) = 5000 psi = 5PLI / mil
σ = 0.5 PLI / 0.5 mil = 1000psi E = 200,000 psi ε = σ/E = (1000)/(200000) = 0.005 = 0.5%
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Tension/Strain Ra7o
For webs with difficult to define thickness, tension to strain ra7o can be a useful replacement for modulus.
εΔΔ
=TK '
Tension
strain, ε
(force/width)
(%)
'KT ε=
'KT
=ε
ε = 0.01 = 1% K’ = 50 PLI T = εK’= (0.01)(50) = 0.5 PLI
T = 2 PLI K’ = 40 PLI ε = T/K’ = (2)/(40) = 0.05 = 5%
T
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Fric7on Coefficient
The fricOon coefficient, m, is the raOo of fricOonal force relaOve to normal load. Two common fricOon coefficient measurement methods are:
Sliding Block Test
WF
=µ
FricOon
Applied Force W
LRISE
LRUN
RUN
RISE
LL
=µ
Incline Plane Slide Test
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The Belt Equa7on
µθeFF
LO
HI =
For simple rollers, the belt equa7on is a useful equa7on, describing the fric7on that develops between a web and roller.
FHI = High Tension, lbs FLO = Low Tension, lbs µ = Web-roller coefficient
of friction θ = Wrap angle, radians
Web slides over non-‐rota7ng cylinder
θ
FHI
FLO Force to Begin Slip and Lib
θ
FLO
Force to Begin Slip and Drop
FHI
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Measure Fric7on (Web-‐Roller)
µθeFF
LO
HI =
θ
TLO THI
W
( )θ
µ LOHI FFln=
Use the belt equaOon to determine web to roller fricOon. 1. Take a strip of web and tape loops on each end.
Arach a mass to one end and weight it with the force gauge.
2. Wrap the target roller with a known wrap angle.
3. If necessary, hold the roller so it doesn’t rotate. 4. Pull with the force gauge un7l the web slides on
the roller, note the force, F (Tension ra7o is F/W).
5. For a second data point, push with the force gauge, dropping the tension un7l the web slips the other direc7on. Note the force, F (Tension ra7o is W/F).
6. Enter the tension ra7o and wrap angle (in radian) in the belt equa7on and calculate fric7on coefficient.
F
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What is the Poisson's ra7o?
The Right Tension Qs
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Strain = Dimensional Change
FT = 0 FT > 0
For solid materials, tensile and compressive stresses do not significantly change density.
Increases in length (MD strain) is offset by decreases in the width and thickness.
Tensioning Increases Length
Thickness & Width
Decrease
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TD Contrac7on
⎟⎠
⎞⎜⎝
⎛−=−=twEFX
XY ννεε
)(0 XT ww νεδ −= FX
Tension, thickness, width, modulus (stretchiness) and Poisson’s raOo determine how much the web will contract.
No Tension
Tensioned
width
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What is elas7city? What is visco-‐elas7city?
The Right Tension Qs
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KEY CONCEPT
ElasOc vs. ViscoelasOc Behavior Elas7c materials respond to stress with an immediate strain change and recover to ini7al dimensions when stress is removed. Viscoelas7c materials will have a 7me-‐dependent response to stress or strain.
Use: Most webs can be considered elas7c. Example: Tensioning a web will create an immediate stretch (a.k.a. strain), that is independent of 7me or speed.
!
Use: Under constant load, a viscoelas7c webs will con7nue to stretch over 7me. Example: Hang a weight on a strip of vinyl electrical tape and measure the length over 7me.
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Elas7c Behavior
σ
ε
7me
7me
Elas7c Response
Response
Input
Elas7city ElasOc materials will respond proporOonally and immediately (at the speed of sound).
Applied stress will result in web strain.
Applied strain will result in web stress.
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Viscoelas7c Behavior -‐ Creep
σ
ε
7me
7me
Elas7c Response
Viscoelas7c Response
Response
Input
Creep Test
A constant stress is applied to the web.
Response is strain.
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VE Behavior – Stress Relaxa7on
ε
σ
7me
7me
Elas7c Response
Viscoelas7c Response
Response
Input
Stress Relaxa7on A constant strain is applied to the web.
Response is stress.
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Viscoelas7c Behavior -‐ Creep
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Viscoelas7c Behavior -‐ Creep
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Viscoelas7c Behavior -‐ Creep
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1.2 Bagginess and Curl What is…? What causes…?
Timothy J. Walker, TJWalker + Associates Inc. 1620 Edgcumbe Road, Saint Paul, MN 55116
[email protected] www.webhandling.com 651.686.5400
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How thick is a web?
} The answer to this is oben a easy, but not always.
• Easy: Foil, most films, coated papers • Confusing: Papers? Thickness can be measured, but are more oben described by ‘weight’ (i.e. mass per area).
• Difficult: Non-‐wovens, tex7les, porous films (anything easily compressed).
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Thickness, Thickness Profile
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What is a web’s thickness profile?
} Thickness mapped vs. width.
} Does the web have thick edges? Lanes?
} Is the thickness profile consistent over 7me?
} Does the product have inten7onal thickness profile (including coa7ngs or cutouts)?
} How is thickness profile measured? (Besides in winding defects)
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Thickness, Thickness Profile
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} Manual physical measurement Increase accuracy by measure a stack mul7ple sheets 10 layers, then divide by number in stack.
} Automated Off-‐Line } Beta radia7on transmission } Capacitance } Physical contact (LVDT) } Mass per area weight sampling
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Measuring Thickness
Capacitance
Absolute Contact
Combined
www.oaklandinstrument.com
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} Automated On-‐Line } Radia7on (beta, x-‐ray) transmission } Radia7on (gamma) backscarer } Near infrared (transmission, reflec7on) } Capacitance } Laser micrometer } Laser curtain on roller
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Measuring Thickness
Scanning
www.ndc.com
Same Spot Differen7al
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Thickness Profile Measurement Op7ons
www.sbi.at
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Closed-‐Loop Thickness Profile Control
Thickness profile measurement is oben
combined with sobware and controls to make automa7c adjustments of
extrusion or coa7ng dies.
www.sbi.at
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Solu7ons to Imperfect Webs
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Baggy Webs
Cambered Webs
Cambered and Baggy Webs
Curled Webs
Non-‐Flat Webs
Bagginess and camber are oben strongly related to
winding.
Curl is strongly related to coa7ng and lamina7ng
(and some7mes winding).
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What is web bagginess? What is web camber? What is web curl?
Imperfect Web Solu7ons Ques7ons
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How are they measured?
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Definition: A web with crossweb length variations. A web is considered baggy if the strain of tension does not pull the web to flatness.
Measuring Bagginess: • There are many methods to qualify or
quantify bagginess. • Most are difficult, expensive, or time-
consuming. • A manual pull out and 1-to-5 grading
may be the simplest. • For films, roll hardness can be a
useful predictor or bagginess.
2A: Baggy Web
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2B: Skew/Camber
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Definition: Skew (a.k.a. Camber) is the most common term for a non-straight web. A cambered web will bend left or right when rolled out under no tension. (Slit strands cut from baggy web may be skewed.)
Skew
Measuring Skew: Skew is typically measured by pulling, rolling, or sweeping out a long sample on a tabletop or floor and quantifies the left or right bias of the web relative to straightness.
Long and Loose Edge
Short and Tight Edge
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Definition: Curl is the tendency for a web to not lay flat (especially coated or laminated webs), instead form into a curved or scroll shape.
Measuring Curl: Curl is best measured in narrow strip samples. Strips samples are usually cut in the machine or transverse (crossweb) direction, but may be cut at any angle.
2C: Web Curl
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Tensioning Baggy Webs
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T0 = 0
T1 > 0
T0 = 0
T1 > 0 T2 > T1
The ideal web carries tension uniformly across the web width.
For an imperfect web, tension stretches the short lanes first. When short lanes are stretched to equal the long lanes, the web appears taut.
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Cambered Web (a.k.a. Skewed Web)
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A cambered or skewed web has one side longer than the other.
A cambered web will curve left or right when rolled or swept out on the floor.
Straight Web
Cambered Web
Long Side
Short Side
Long Side
Short Side
Cambered Web Cut into Strips
All Lanes Equal
Straight Web Cut into Strips
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SliOng Baggy or Cambered Web
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If a slit roll is cut from a baggy web across a lane in the transition
from short to long lanes, the slit roll will be cambered.
Short Lane
Long Lane
Short Lane
Short Edge Long Edges
Short Edge
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What causes TD length varia7ons in paper, film, or foil manufacturing ?
Imperfect Web Solu7ons
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A short, but not complete list why paper, film, and foil making has TD length variations includes: Machine misalignment Crossweb moisture variations Uneven calendaring Variation in roller diameters Uneven web paths or nip loads in blown film collapsing Cooling or stress variations in tenter quenching zone Nip variations in laminating or film extrusion nips
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More on Curl… More on Bagginess…
More on curl in Sec7on 4 Nipped Rollers and Lamina7ng
More on bagginess in Sec7on 6 Winding and Roll Quality
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Tension Control 1. How do you determine the target web handling tension for a
given product in units of force or force per width? 2. What are three causes of tension varia7ons across the web’s
width (i.e., things that create a loose edge or center). 3. What advantage does a dancer roller have over a tension load cell
roller in a closed-‐loop tension control system. 4. What advantage does a tension load cell roller have over a dancer
roller in a closed-‐loop tension control system. 5. What are advantages and disadvantages of draw control (a.k.a.
speed ra7o control).
Web Handler’s Quiz
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Rollers, TracOon, Nipping/LaminaOng 6. What is a reasonable specifica7on for roller alignment in mm/m,
milli-‐radians, or mils/in.? 7. Which rollers in a process are like to have above average
diameter? Why? 8. When is a nipped roller needed on a driven roller separa7ng two
tension zones? 9. What is a simple measurement to determine if two nip rollers are
pressing together uniformly? 10. If a two-‐layer laminate product curls to the top layer in the
machine direc7on, which would reduce the curl: increase or decrease the top layer pre-‐laminate tension?
Web Handler’s Quiz
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Tracking, Wrinkling 11. For automa7c guiding in the middle of a process, which is
preferred: a steering-‐type guide or a displacement-‐type guide? 12. In a ver7cal span, which will cause the web to track off center
more, a roller tram (misalignment vs. machine center line) or level error (misalignment rela7ve to gravity)?
13. Name four mechanisms that will cause the web to track off centerline through a series of rollers.
14. If you see wrinkles at low speeds, but the wrinkles go away at higher speeds, what is the most likely reason?
Web Handler’s Quiz
TJWA Inc., Copyright 2012 www.webhandling.com 84
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Wrinkling, Spreading 15. If a roller is deflec7ng into a bowed shape due to gravity, which
direc7on is it best NOT to approach that roller if you don’t want to wrinkle: ver7cally from above, ver7cally from below, or horizontally?
16. What spreader or an7-‐wrinkle rollers do NOT have a rubber surface?
Web Handler’s Quiz
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Webs Tension Rollers Nips Lateral Wind More
Winding, Unwinding 17. If you center wind at constant torque, what is the percent change
in tension if the roll diameter changes from 100 mm to 400 mm? 18. If you wind a paper and a film product of equal thickness and roll
geometry at the same combina7on of winding condi7ons (tension, nip, taper, speed), which is likely to have higher internal roll pressures?
19. Name three advantages of using a nipped or gap-‐controlled roller ahead of winding?
20. What is an easy way to determine if an unwinding roll is cinching (i.e., some of the roll’s layers are slipping in the machine direc7on?
Web Handler’s Quiz
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Apply Torque to Rollers and Rolls
Driven Rollers/Rolls Clutched Rollers/Rolls
Braked Rollers/Rolls
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Open-‐Loop Torque Motor
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Unwinding Op7ons
Open-‐Loop Brake
Brake with Diameter Feedback
Brake with Load Cell Feedback
Brake with Dancer Feedback
Motor with Diameter Feedback
Motor with Load Cell Feedback
Motor with Dancer Feedback
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Unwinding Op7ons
Surface Roller Driven Unwind
Brake with Load Cell Feedback
Brake with Dancer Feedback
Surface Belt Driven Unwind
VV
V
V
Surface driven unwinds are typically speed ra7o controlled, but could be closed-‐loop tension control with load
cell or dancer feedback.
Surface roller /belt
Surface roller /belt
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Unwinding Peel Roller Op7ons
Driven Unwind with Idling Peel Roller
Braked Unwind with Idling Peel Roller
Peel rollers are lightly loaded against the unwinding roll and may be driven to reduce the tension increase due to peel force.
Braked Unwind with Driven Peel Roller
Driven Unwind with Driven Peel Roller
Peel roller are used to reduce web path varia7ons from peel force
varia7ons (for unlinered adhesive coated webs or other products with side A to B bonding forces).
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Web Support / Transport / Tensioning Op7ons
Rectangular Bar / Plate
Curved Bar / Plate
De-‐Curl Bar / Roller
Roller
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Web Support / Transport / Tensioning Op7ons
+P
Air Greased Bar / Plate
Roller Curved Bar / Plate
+P
Air Float Bar / Plate
Webs Tension Rollers Nips Lateral Wind More
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Web Support / Transport / Tensioning Op7ons
Vacuum Roller
Nipped Roller
Unnipped Roller
-‐P
µθeTT
LO
HI = NT µ=Δ ( )TwrPfT ,,,,, θµ=Δ
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Roller Op7ons – Live vs. Dead Shab, Idler vs. Driven
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Live Sha` Idler Roller Dead Sha` Idler Roller
Bearings
Live Sha` Driven Roller
Shab rotates with shell. Shab does
not rotate.
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Winding Op7ons: Center Driven
Center+Surface Driven Winder
Center Driven Winder
Surface Driven Winder
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Open-‐Loop Torque Motor
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Winding Op7ons: Center Driven
Open-‐Loop Clutch
Clutch with Diameter Feedback
Clutch with Load Cell Feedback
Clutch with Dancer Feedback
Motor with Diameter Feedback
Motor with Load Cell Feedback
Motor with Dancer Feedback
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Winding Op7ons: Surface Driven
Surface Roller Driven Winder
VV
Surface Belt Driven Winder
V
V
Brake with Load Cell Feedback
Surface roller /belt
Brake with Dancer Feedback
Surface roller /belt
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Winding Op7ons: Center-‐Surface Driven
Surface Belt Driven Winder
V
V
Brake with Load Cell Feedback
Surface roller /belt
Brake with Dancer Feedback
Surface roller /belt
Surface Roller Driven Winder
VV
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Roller Op7ons
Live Sha` Idler
Dead Sha` Idler
Dual Bearings
Direct Driven Roller
Torque Driven Roller
Tendency Driven Roller
Idler Roller Op7ons Driven Roller Op7ons
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Can7levered Roller Op7ons
Dual-‐Wall CanOlevered Sha`
CanOlevered Support
CanOlevered Sha`
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Web Proper7es WHAT IS IT Descrip7on What are the sub-‐technologies?
Intro Level Learning? • Thickness, Width • Young’s Modulus of Elas7city • Surface (Fric7on, Roughness,
Porosity) • Breaking, Yielding • Poisson’s Ra7o • Layers? Laminate? Coated?
Advanced Level Learning? • Visco-‐elas7city? • Anisotropy? (MD-‐TD Differences) • Thickness measurement and profiles • Bagginess and Curl • Memory • Thermal Expansion • Hygroscopic Expansion • Variable geometry: discon7nui7es
(holes, patches), profiled cross-‐sec7on, widgets
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Web Proper7es WHAT IS IT Where is it used?
Paper, Film, Foil, Packaging, Medical/Pharmaceu7cal, Electronics, Construc7on, Magne7c, Imaging, Op7cal, Barery, Solar, Food, Carpet/Tex7le
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WH Technology PROFIT (or LOSS) = BENEFITS -‐ COSTS What is profit (or loss) of doing it well? • Con7nuous processing webs is more efficient (higher yields, higher
produc7vity) than sheet or part processing. • Using thin webs reduces material costs. • Using marginal quality (baggy) webs to make product reduces
waste, lowers costs.