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AIMCAL Europe 2012 Web Handling Conference Prague, Czech Republic Guidelines for Selecting the Best Winding Process for Your Products R. Duane Smith Product Manager – Specialty Winding Davis-Standard, LLC 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 Roll Hardness vs. Diameter Hardness Taper 120 100 80 Ideal Hardness Taper 60 Maximum Hardness Taper Minimum Hardness Taper 40 20 0 Core Diameter 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) MaterialsTension is the dominant principle High Modulus (Stiff) MaterialsNip 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 inwound 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 [email protected]