Nip roll indexing-

It's not obvious how winding adds value to your product it does , but it is obvious when it's done poorly. Winding — the final step in many web converting processes — is like bagging groceries. You go through the store. Pick out bread, eggs, and milk. At the checkout line, the checkout assistant opens a bag, drops in your bread, then your eggs, then the gallon of milk — splat.

Nip roll indexing

Nip roll indexing

Nip roll indexing

Winding rolls can have one or all of these errors, especially diameter variations. A winding nip after the web tangent point still will have some air squeegee and induced-tension benefits. While this step and repeat combination does create tremendous cost savings in terms of foil, speed limitations were, and still are, a cause for concern due Nip roll indexing substrate bonding, the heat transfer process, Was jesse metcalfe fired the mechanical registration process. As the roll indexes away from the winding nip, the winding entry span length increases. Get the Nip roll indexing. A: Air is entrained with the moving web's surface on both the entering web and the outside of the winding roll. A: If you survey winding equipment shown at the CMM show, center winding dominates the converting industry.

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There are three Beaver falls bishop winding processes used for web materials: center winding, surface winding, and combination center-surface winding. The function of the last roller before entering the winding roll is critical to optimized roll quality. In Criel model to ATS, cantilevered, non-woven, H Beam and Surfastart technology, we supply roll handling Nip roll indexing die control, transfer and splicing systems and no waste designs to boost your productivity and ROI. A winding nip after the web tangent point still will have some air squeegee and induced-tension benefits. If your product has high friction or adhesive coating, the outer layer will not slip relative to the winding roll, so Nip roll indexing can't benefit from nip-induced tension. Eagle has been able to double their press speed to sph to achieve the same move in 0. As mentioned above, surface winding is good for rolls with large build-up ratios. This winder is widely used among hygienic film producers for applications such as diaper film, breathable film, and non-woven coating processes. At the checkout line, the checkout assistant opens a bag, drops in your bread, then your eggs, then the gallon of milk — splat. Finally, it tightens the winding roll. Some of the same roll quality benefits also are found using a close cousin of the winding nip — the gap roller. Semi or automatic core loading with precision core positioning and core cutting options. First, it reduces the span length into the winding roll, reducing tracking errors and wrinkling. The revolutionary design of the TEC-2 simplifies center winders by eliminating the turret. Please address comments to author s.

In the laminate business, pinch rolling often called nip rolling is a process where powered rolls are used to press together multiple sheets of material.

  • This robust injector-style tension unit, is designed for 30 second roll changeover and includes a provision for the future addition of a multiple indexing station and up to three additional sets of tension rolls for use with multiple types of materials.
  • Chill rolls may looks simple and shiny, but they play a critical part in cooling and polishing film and sheet and are not all the same.
  • An extensive amount of pressure was applied to foil ribbons in those early days of hot foil stamping.

It's not obvious how winding adds value to your product it does , but it is obvious when it's done poorly. Winding — the final step in many web converting processes — is like bagging groceries.

You go through the store. Pick out bread, eggs, and milk. At the checkout line, the checkout assistant opens a bag, drops in your bread, then your eggs, then the gallon of milk — splat. Winding is like that. One key to quality wound rolls is the winding nip. Some of the same roll quality benefits also are found using a close cousin of the winding nip — the gap roller.

A: Yes, winding nip rollers are used in both. You can't have a surface winding without a winding nip roller a. A two-drum winder has two winding nips that cradle the winding roll and often a third winding nip on top of the roll. Adding a winding nip to a center winder improves roll quality. A: If you survey winding equipment shown at the CMM show, center winding dominates the converting industry.

This dominance is not because it is the best winding method, but because it is simpler to build and easier to automate roll transfers. First, paper roll properties allow winding to extremely large-diameter build-up ratios, where the final roll's diameter may be 20x the core diameter.

Surface winding takes roll diameter out of the torque range requirements. If there is a core start wrinkle, the soft paper layers quickly mask them.

A: It's not about which is better. They both have important niches. As mentioned above, surface winding is good for rolls with large build-up ratios. Surface winding often can wind at lower tensions than center winding and exerts less torque on the building roll avoiding torque-related cinching. For many products, center winding is better for winding multiple rolls on a common shaft, especially with differential winding bars.

Mismanagement of the web's final span before winding is like the poor grocery bagger. A: The winding nip has four main functions. First, it reduces the span length into the winding roll, reducing tracking errors and wrinkling. Second, it acts as a squeegee, reducing the air entrained into the winding roll. Finally, it tightens the winding roll.

A: The three sources of web tracking error are misalignment, diameter variations, and web bagginess. Winding rolls can have one or all of these errors, especially diameter variations. Because the web's flexibility goes up with span length cubed, the magnitude of tracking error from these sources will increase with longer entry spans. A: Many turret winders have wrinkles and tracking error during the index cycle. As the roll indexes away from the winding nip, the winding entry span length increases.

In many cases, the non-cylindrical winding roll and the long span formed during indexing will cause wrinkling or tracking error. A: In some designs, rollers on the turret that limit the span length during indexing are enough. A: The cross-web caliper variations and slit edge quality create roll diameter variations. Winding conditions and material properties such as the radial modulus will determine whether winding magnifies or masks web thickness variations.

The winding nip then holds the web in place as it presses it onto the winding roll, ensuring a laterally aligned roll edge. The traction of the web to the winding nip holds the web in position, preventing web reaction to the airflow at the web-roll convergence.

A: A compliant winding nip is best, since the compliant covering will reduce the cross-web nip pressure variations from roll diameter variations.

An overly hard winding nip roller may ride only on the high diameter lanes, creating stress concentrations in the web. If you need to ensure lateral tautness at winding, use a spreader roller just upstream of the winding nip.

If the web is flat on the winding nip, it will be flat entering the roll. A: Yes. For many products, the winding nip pressure will compress the high diameter areas. Both effects tend to improve roll cylindricity. Q: Should a winding nip be held parallel or allowed to float to the roll's profile? A: Floating winding nips can promote tracking errors. A: Air is entrained with the moving web's surface on both the entering web and the outside of the winding roll.

The boundary layer of air travels at nearly the web's speed. Without a winding nip, the high- velocity air creates high pressure at the web-roll convergence. An unnipped web, which creates only low pressure less than 1 psi , can be lifted by the air velocity pressure.

A: Not always. Air can be a great masker of caliper and diameter variations. However, if the air bleeds out over time, the roll layers will settle to a small diameter and loosen the roll. Winding in a vacuum process quickly reveals the benefits of entrained air. Without entrained air, caliper variations translate strongly into diameter variations, and often wrinkling.

Keith Good at the Oklahoma State University Web Handling Research Center did some excellent work over the last decade to understand and predict how a winding nip increases tension. The nip force of the cart's weight on the wheels has a rolling pin action, elongating the rug. As the cart rolls in one direction, the rolling wheels elongate and pin down the stretched rug.

The elongated material is pushed ahead of the cart, forming a bulge in the carpet. If you held the rug at both ends while you rolled the cart, you would find the rug behind the cart got tighter and the rug section ahead of the cart got looser. This same elongating and pinning happens with a winding nip, only in the reverse direction. The web moving under the nip is elongated and pinned onto the winding roll. Therefore, the web tension increases as the web passes under the winding nip.

A: In both the rug and winding nip case, the top layer or rug must slide relative to the surface below it to elongate. If the layer or rug can't slide, it can't elongate. The interesting finding from Dr. Good's work is the winding nip tightening must exceed the break-away friction, but it also is limited by it. Therefore, front-to-back web coefficient of friction or rug to floor friction determines how much elongation or tensioning occurs for a given winding nip load.

The benefit of nip-induced tension is that it can reduce the tension that must be transmitted through a center winding roll. Too much center torque can lead to cinching and telescoping. Winding nip tension can create a tighter roll without these defects. A: There should be some wrap on the winding nip, so the web is placed onto the roll by the nip.

If the web touches the roll then later is nipped, some of the anti-wrinkle and improved tracking benefits are lost. A winding nip after the web tangent point still will have some air squeegee and induced-tension benefits. The best winding nip geometry is a deg wrap. This does two things. First, it orients web tension perpendicular to winding nip force, making the winding nip load independent of tension. Second, if the winding nip roller deflects or skews, a deg nip wrap ensures it will be perpendicular to the entry span, reducing the likelihood of tracking or wrinkling.

Instead, as the name implies, the gap winding positions the final roller at a small gap from the winding roll's outer surface, creating an extremely short entry span. A: A gap roller has the same anti-wrinkle and improved tracking benefits of a pack roller. However, since it doesn't create pressure or force on the outer layer, there is no air squeegee or nip-induced tension benefits.

A: If you want the tracking and wrinkling benefits, but have a pressure- or tension-sensitive product, then gap winding is a better option. If your product has high friction or adhesive coating, the outer layer will not slip relative to the winding roll, so you can't benefit from nip-induced tension. If you find entrained air improves your winding quality, gap winding is better for your product. The function of the last roller before entering the winding roll is critical to optimized roll quality.

Nip and gap winding both will reduce lateral errors and wrinkling associated with long entry spans and roll variations. Winding nips will reduce entrapped air, and the associated loose wind or vacuum process pump downtimes. Winding nips are an alternate variable to increase roll tightness and may promote roll cylindricity. Just like a good grocery assistant will put your milk and eggs in a bag safely, nip and gap winding will secure your web safely onto the winding roll. Timothy J.

He specializes in web handling education, process development, and production problem solving. You need JavaScript enabled to view it. Please address comments to author s. View Our E-Clips Archive. Subscribe to E-Clips.

It has to be strong enough to resist deflection and damage from the nip force. Davis-Standard offers custom unwind and winder equipment with cantilevered shafts for a variety of applications including polystyrene foam, film, and paper. In addition, center winders have a higher probability of generating scrap during roll changes. A: It's not about which is better. The dual pivoting shaft design allows for manual roll removal or optional automatic roll removal and re-coring on the 4. A cooling roll may look simple, but in reality it is a complex mechanical and a thermal device all in one.

Nip roll indexing

Nip roll indexing

Nip roll indexing

Nip roll indexing. Coil Processing Equipment

One key to quality wound rolls is the winding nip. Some of the same roll quality benefits also are found using a close cousin of the winding nip — the gap roller. A: Yes, winding nip rollers are used in both.

You can't have a surface winding without a winding nip roller a. A two-drum winder has two winding nips that cradle the winding roll and often a third winding nip on top of the roll.

Adding a winding nip to a center winder improves roll quality. A: If you survey winding equipment shown at the CMM show, center winding dominates the converting industry. This dominance is not because it is the best winding method, but because it is simpler to build and easier to automate roll transfers.

First, paper roll properties allow winding to extremely large-diameter build-up ratios, where the final roll's diameter may be 20x the core diameter. Surface winding takes roll diameter out of the torque range requirements. If there is a core start wrinkle, the soft paper layers quickly mask them. A: It's not about which is better.

They both have important niches. As mentioned above, surface winding is good for rolls with large build-up ratios. Surface winding often can wind at lower tensions than center winding and exerts less torque on the building roll avoiding torque-related cinching. For many products, center winding is better for winding multiple rolls on a common shaft, especially with differential winding bars.

Mismanagement of the web's final span before winding is like the poor grocery bagger. A: The winding nip has four main functions. First, it reduces the span length into the winding roll, reducing tracking errors and wrinkling. Second, it acts as a squeegee, reducing the air entrained into the winding roll.

Finally, it tightens the winding roll. A: The three sources of web tracking error are misalignment, diameter variations, and web bagginess. Winding rolls can have one or all of these errors, especially diameter variations. Because the web's flexibility goes up with span length cubed, the magnitude of tracking error from these sources will increase with longer entry spans. A: Many turret winders have wrinkles and tracking error during the index cycle.

As the roll indexes away from the winding nip, the winding entry span length increases. In many cases, the non-cylindrical winding roll and the long span formed during indexing will cause wrinkling or tracking error. A: In some designs, rollers on the turret that limit the span length during indexing are enough.

A: The cross-web caliper variations and slit edge quality create roll diameter variations. Winding conditions and material properties such as the radial modulus will determine whether winding magnifies or masks web thickness variations. The winding nip then holds the web in place as it presses it onto the winding roll, ensuring a laterally aligned roll edge. The traction of the web to the winding nip holds the web in position, preventing web reaction to the airflow at the web-roll convergence.

A: A compliant winding nip is best, since the compliant covering will reduce the cross-web nip pressure variations from roll diameter variations. An overly hard winding nip roller may ride only on the high diameter lanes, creating stress concentrations in the web. If you need to ensure lateral tautness at winding, use a spreader roller just upstream of the winding nip. If the web is flat on the winding nip, it will be flat entering the roll. A: Yes. For many products, the winding nip pressure will compress the high diameter areas.

Both effects tend to improve roll cylindricity. Q: Should a winding nip be held parallel or allowed to float to the roll's profile? A: Floating winding nips can promote tracking errors. A: Air is entrained with the moving web's surface on both the entering web and the outside of the winding roll. The boundary layer of air travels at nearly the web's speed. Without a winding nip, the high- velocity air creates high pressure at the web-roll convergence.

An unnipped web, which creates only low pressure less than 1 psi , can be lifted by the air velocity pressure. A: Not always. Air can be a great masker of caliper and diameter variations. However, if the air bleeds out over time, the roll layers will settle to a small diameter and loosen the roll.

Surface-type film winders use a driven winding drum. The winding rolls are loaded against the drum and are surface wound. Duane Smith. A lot of science goes into winding. We will discuss the winding principles, how they are used on different types of winders, and present product parameters for which each type of winder is best suited. Roll hardness is developed in different ways on different types of winders but the basic principles of how to build roll hardness stay the same.

When winding elastic films, web tension is the dominant principle of winding used to control roll hardness.

The winding web tension is often determined empirically. When relying only on tension to control roll density, it is important that the winding tension be tapered smoothly as the roll diameter increases. When winding inelastic webs, nip is the dominant principle used to control roll hardness.

Web tension is controlled to optimize the slitting and spreading operations. The nip controls the roll hardness by removing the boundary layer of air following the web into the winding roll. The rolling nip also induces in-wound tension into the roll. The harder the nip, the harder the winding roll will be.

The challenge for winding is to have sufficient nip to remove the air and wind hard, straight rolls without introducing too much in-wound tension in order to prevent roll blocking or deformation of the web over the high-caliper area. Torque winding is the force induced through the center of the winding roll, which is transmitted through the web layers and tightens the inner wraps.

This torque is used to produce the web tension when center winding. Film winding is often referred to as an art. This is because the setting and programming of the TNT will vary depending on:. There are three basic winding processes used for web materials: center winding, surface winding, and combination center-surface winding.

A center winder could be a gap winder where only tension is used to control roll hardness. In center winding, the spindle torque through the center of the roll provides the web tension.

This type of turret winder can provide quick indexing and fast cycle times. In addition, center winders have a higher probability of generating scrap during roll changes. When surface winding elastic materials, web tension is the dominant winding principle. When surface winding inelastic materials, nip is the dominant winding principle.

Jump to navigation. The NPAT is used to capture nip footprints and relative pressure distribution between nip rolls. Download Datasheet. Not available for online purchase. The tool measures and displays, in real-time, nip widths between 6.

Software showing roller misalignment. Software showing heavy crown or misalignment. There are nine standard systems that each have their own spacing. All systems have a nip sensing width between The system is able to measure pressures of up to 4, psi.

These systems are ideal for larger rolls in the printing industry. This system is ideal for smaller rolls in the film and converting industry. It has a streamlined set of features that allows the user to easily identify nip uniformity. The pressure distribution across each band is displayed and can be saved as a snapshot of the image. Compare previous reference snapshot. Watch the Video. Proper pressure distribution between rolls allows for an efficient manufacturing process and the production of a uniform product.

How can pressure mapping help? Get the eBook. I-Scan and Pressure Indicating Film are two technologies commonly used to verify nip uniformity. Which one is right for your operation? Machines have a story to tell, but many may lack the ability to communicate with their operator. See how pressure mapping technology can help start a productive conversation between you and your machine. Dental Digital Occlusal Analysis. Nip Pressure Alignment Tool. Check out this short video to see how NPAT can capture critical nip roll uniformity data in minutes!

Machine Alignment Insights with Pressure Mapping Technology Machines have a story to tell, but many may lack the ability to communicate with their operator. To print this web page, please use our "share" tools. Benefits of Measuring Nip Pressure: Clear visual representation of pressure distribution, nip width, and cross width Ensures proper alignment Prevents equipment and product damage Provides quantifiable and credible data Easily maintained in-field.

Machine Comparison Preventative Maintanence Misalignment. Crowns Diameter Variations Deflections.

Nip roll indexing

Nip roll indexing

Nip roll indexing