Guidelines for Selecting the Best Winding Process for

Your Products R. Duane Smith Product Manager – Specialty Winding Davis-Standard, LLC

AIMCAL Europe 2012 Web Handling Conference Prague, Czech Republic

There is a lot of Science that goes into Winding

The Winding Principles are well established and have been proven and

modeled at the Web Handling Research Center at OSU*

*Oklahoma State University, Stillwater, Oklahoma, USA

This presentation will discuss: • These Winding Principles • How they are used on different types of

winders. • Present the Product Parameters that each

type of winder is best suited for.

Goal of the Presentation- To assist you in determining the best type of winder to use for consistently producing quality, defect free rolls of your web material

Roll Hardness The Critical Factor in Determining the Difference Between A Good Roll & A Bad Roll Secret to building a Good Structure • Build a good solid foundation. • Then wind with progressively

softer roll hardness

Proven Fact: As Roll Winds - Inwound Tension Or Residual

Stresses Build Up Inside The Roll If Stresses Become Greater As Roll Winds Larger -

Inner Wraps Towards The Core Will Loosen & May Even Go Into Compression

This Causes Rolls To Contain Defects Such As Telescoping, Buckling &/or Starring

ROLL HARDNESS MUST BE PROFILED TO PREVENT THIS!

Roll Hardness Profiles

0

20

40

60

80

100

120

Har

dnes

s Ta

per

Diameter

Roll Hardness vs. Diameter

Ideal Hardness TaperMaximum Hardness TaperMinimum Hardness Taper

Core Full Roll

Suggestion on how to remember the Winding Roll Hardness Principles

The Three Winding Principles used for consistently Winding Dynamite Rolls are:

T.N.T.

T.N.T. Winding Principles : Tension - The WINDING WEB

Tension Nip - The NIP of the Pressure

Roll or Drum Torque - The TORQUE from the

Center Drive or Torque Drum

Winding Principles verses Material Characteristics Low Modulus (Stretchy) Materials- Tension is the dominant principle High Modulus (Stiff) Materials- Nip and Torque are the dominant principles.

How much Tension should you use? Web Tension Guidelines published in AIMCAL’s Converting Quarterly Page 58, Issue 2011, Quarter 3

Extensible Films- Web Tension is Dominate Winding Principle

How To Determine the Maximum amount of Tension

to Wind Film Webs at ????

Maximum Allowable Tension –Empirical data has shown that a

tensile stress of 1.5% of the elastic modulus, or Modulus of Elasticity, can be applied without inducing significant permanent stresses in film webs.

Modulus of Elasticity Some typical secant moduli are: •Flexible PVC 350- 560 kg/cm2 (5-8 kpsi) •LDPE 1,000-1,800 kg/cm2 (15-25 kpsi) •LLDPE 2,000-2,800 kg/cm2 (29-40 kpsi) •HDPE 5,600- 9,100 kg/cm2 (80-130 kpsi) •BOPP 7,700- 24,000 kg/cm2 (110-350 kpsi) •PET 14,000- 38,000 kg/cm2 (200-550 kpsi)

Maximum Allowable Tension Example: Maximum Tension of 50 micron (.05mm) LDPE Assume a modulus of 1,400 kg/cm2 (LDPE) 1.5% of 1,400 is .015 x 1,400 or 21 kg/cm2 For a 1500mm wide x .05mm thick web 1500mm x .05mm x .21 kg/mm2 = 15 kg Max. Tension.

Try to keep web at or below this tension during

processing

Tension Principles of Winding

Taper Tension –Reduce the tension smoothly as

the roll diameter increases •0 - 50% taper, 25% common

–Taper Tension reduces roll defects such as - Telescoping, Buckling and Starring

NIP Principle of TNT Winding

Nip of Winding Rolls : • Removes the boundary layer of air following

the Web. • Adds Inwound Tension - The higher the nip,

the harder the rolls. Challenge is to have sufficient nip to Wind

hard & straight rolls without winding in too much inwound tension to prevent blocking and deforming the web over caliper bands.

NIP Principle of TNT Winding

• Nip must be applied where web enters the winding roll.

• The winding roll’s & lay-on roll’s weight and web tension should not affect the Nip loading.

NIP Principle of TNT Winding • Nip Load should be

tapered as roll winds to prevent starring and telescoping.

• However, larger winding roll’s dia. drags more air and produces a larger footprint for Tapered Loading Pressure with a constant loading force.

Gap Winding Air sometimes wants to be wound into the

winding roll of material to: • Prevent blocking problems • Prevent deforming the web that is

wound too tightly over gauge bands Lay-on Roll should follow the Winding

Roll’s Surface with a Small Controlled Gap – Directs the web squarely into the winding roll.

TORQUE Principle of TNT Winding

• Torque cinches the inner layers while winding • Torque produces Web Tension when Center Winding • Torque Independent from Web Tension when C/S Winding

TORQUE Principle of TNT Winding Typically, the winding tension starts at 25-50% greater than the incoming web tension and then this winding tension is tapered as the roll builds in diameter to a value at or even less than the incoming web tension.

Basic types Winding Processes –Center Winding –Surface Winding –Combination Center/Surface

Winding EACH TYPE USES ONE OR

MORE OF THE T.N.T. PRINCIPLES TO BUILD ROLL HARDNESS

Center Type Winder

Tension & Nip are Dominant Winding Principles

Center Winders Gap Winding - Use web Tension only.

(Web tension provided by spindle torque)

Contact Winding - Use web Tension and Nip To control roll hardness

Advantages - Can build softer rolls. Quick indexing, fast cycle times.

Disadvantages - Limited maximum roll dia. due to torque applied thru layers.

Higher probability of scrap during roll changes.

Center Winders • Best for Winding Small Diameter Rolls • Best for Winding Soft Rolls i.e. Films with Gauge Bands

• Good Control of Inwound Tension • Easily Provides Dual Direction

Winding • Can Provide Adhesiveless Transfers

Turret Center Winders

Drum Surface Winders

Drum Surface Winders Winding Elastic Materials -

Web Tension is dominant winding principle. Winding Inelastic Materials -

Nip is dominant winding principle. Advantage - Web Tension is not supplied from

torque applied thru the roll. Disadvantage - Can not wind air into roll to

minimize gauge bands and roll blocking.

Drum Surface Winders • Best for Winding Very Large Dia. Rolls • Best for Winding Hard Rolls i.e. Protective Films

• Best Utilization of Space and Horsepower • Minimum Waste During Transfers • Less Expensive

– Less Equipment – Single and Smaller Winding Drive

Drum Surface Winders + In-line slitting with little waste + Thread up is simple and accessible + Winding of Large Dia. Rolls of Non-Extensible webs − Tension is not controlled through the wound layers

(tension is only known prior to the drum) − Typically single direction winding only − Requires tape or glue on core for auto. transfers − No gap winding available

Drum Surface Winders

Center/Surface Type Winder

Web Tension Independent Winding Principle from Winding Torque

Center/Surface Winders Can use all three TNT principles -

Tension, which is used for slitting and spreading, controlled by Surface Drive.

Nip is controlled by the lay-on roll loading. Torque from spindle drive controls roll hardness

independent from web Tension. Advantages - Can wind with best control of inwound

tension and improve the ability to produce shippable quality slit rolls off the production winder.

Disadvantages- More costly and complex.

Center/Surface Winders • Best for winding w/ optimum roll quality • Best for winding high slippery webs • Best for slitting and winding to larger

rewind diameters • Best for ability to significantly taper in-

wound tension without affecting the width of extensible webs

• Able to supply in-wound tension without stretching the web over caliper bands

Tech Tip- When to Use Center/Surface Winders

For Information on how to get a copy of any of my Tech Tips or Technical Papers - Please give me your card with Email address

Guide for Selecting the Best Winding Process for Your Products

Suggested Winding Process

1 – Center Winding Process

2 – Surface Winding Process

3 – Combination Center / Surface Winding Process

Material Characteristics Suggested Winding Process

Thin Webs processed at High Speeds 1

Thick Webs wound to Large Diameters 2, 3

Extensible “stretchy” Webs - Large Dia. 2

Non-Extensible Webs - Thin, Small Dia. 1

High Coefficient “Sticky” Materials 1

Low Coefficient “Slippery” Materials 3

Inline Slitting in Multiple Webs 3

Guide helps to determine the best type of winding process. Yet determining the

proportional amount of the T.N.T. Winding Principles for different types of web

materials Is still considered an ART

Setting And Programming Of Tension, Nip & Torque Will Vary Depending On: • Type & Design of Winder • Type of Web Material • Width of Rolls Being Wound • Speed of Winding Operation Different Web Products and Different

Applications Dictate Desired Roll Hardness HARDNESS PROFILE MUST BE REPRODUCED CONSISTENTLY

Roll Hardness Measuring Devices Need To Be Available To Winder Operators • RHOMETER & SCHMIDT HAMMER -

Measures Hardness Across Outer Surface • PAROtester & TAPIO RQP (Roll Quality Profiler)-

Measures Hardness Across Outer Surface • SMITH NEEDLE - Measures Hardness from Core

to Full Roll • RDF Curve (Microprocessor Control System) -

Measures Roll Density During Winding

RHOMETER

SCHMIDT HAMMER

PAROtester

PAROtester

TAPIO RQP (Roll Quality Profiler)

TAPIO RQP (Roll Quality Profiler)

SMITH NEEDLE

AccuWind Roll Density Curves

For Contact Information on these Roll Hardness Measuring Devices: • RHOMETER • SCHMIDT HAMMER • PAROtester • TAPIO RQP • SMITH NEEDLE Please give me your card with Email address

Guidelines for Selecting the Best Winding Process for Your Products

Questions ????

Thank You!

R. Duane Smith Product Manager – Specialty Winding

Davis-Standard, LLC

smithd@bc-egan.com