Roll slitting

Shearing operation

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"Slitting" redirects here. For slitting of iron bars into rods, see slitting mill

Roll slitting is a shearing operation that cuts a large roll of material into narrower rolls. There are two types of slitting: log slitting and rewind slitting. In log slitting the roll of material is treated as a whole (the 'log') and one or more slices are taken from it without an unrolling/re-reeling process. In rewind slitting the web is unwound and run through the machine, passing through knives or lasers, before being rewound on one or more shafts to form narrower rolls. The multiple narrower strips of material may be known as mults (short for multiple) or pancakes if their diameter is much more than their width.[1] For rewind slitting the machine used is called a slitter rewinder, a slitter or a slitting machine &#; these names are used interchangeably for the same machines. For particularly narrow and thin products, the pancakes become unstable, and then the rewind may be onto a bobbin-wound reel: the rewind bobbins are much wider than the slit width and the web oscillates across the reel as it is rewound. Apart from the stability benefit it is also then possible to put very long lengths, (frequently many tens of kilometres), onto one bobbin.

Process

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Soft materials

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Several methods are available for soft materials like plastic films, textiles, adhesive tapes, and paper. Razor blades, straight, or circular blades are being used. Some blades cut through the material while others crush the material against a hard roll. Those are similar to knives. The cutting blades can be set to a desired width. Some machines have many blades and can produce a number of output rolls at once. The slit material is rewound on paper, plastic or metal cores on the exit side of the machine.

The process is used because of its low cost and high precision for mass production. Some machines have a program that monitors the blades and sharpens the blades often to maintain the quality and precision of the cut. Depending on the industry and the product that is being slit these machine can run between 10m/min (special metal webs) and m/min (paper making process). The machines can also incorporate extensive automation to precisely control material tension, automatically position the slitting knives, automatically align the cores onto which the material is wound and to reduce manual handling of the rolls.

Examples of materials that can be cut this way are: adhesive tape, foam, rubber, paper products, foil, plastics (such as tarps and cling wrap), glass cloth, fabrics, release liner and film.

Hard materials

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For harder materials, such as sheet metal, blades cannot be used. Instead, a modified form of shearing is used. Two cylindrical rolls with matching ribs and grooves are used to cut a large roll into multiple narrower rolls. This continuous production process is economical yet precise; usually more precise than most other cutting processes. However, the occurrence of rough edges known as burrs is commonplace on slit edges. Also, the geometry of these rolls is determined by specific tolerances in addition to the type of material and workpiece thickness.[2]

Machinery

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For metal coils, the slitter consists of three main parts: an uncoiler, slitter, and recoiler.[3] The material is fed from the uncoiler, through the nip between the two circular cutting wheels (one on top and another underneath), and then re-wound in slit pieces on the recoiler.

When the term "slitter rewinder" or "slitting machine" is used to describe the machine, the three parts are referred to as the unwind, the slitting section and the rewind. Slitter rewinders are normally used to slit plastic films, paper and metal foils. The unwind stage holds the roll stably and allows it to spin; it is either braked or driven to maintain accurate tension in the material. Some machines have a driven unwind which reduces the effect of inertia when starting to unwind heavy rolls or when the material is very tension-sensitive.

The slitting section has four main options:

• Razor slitting, which is ideal for thin plastic films &#; the system is very simple and quick to set. Although the razor blades are of low cost, they need to be frequently changed to ensure a good quality slit edge.
• Rotary shear slitting. Male and female circular knives engage to give a scissor cutting effect. This system is used widely on paper, films and foils. Although the knives take longer to position, they stay sharp longer than razor blades. The setting time can be reduced by using an automatic knife-positioning system.
• Crush cut slitting. A male knife runs against an anvil. The system works well with certain materials including non-wovens and foams.
• Hot knife slitting. A heated round blade (similar to a score or crush cut blade) or sharpened piece of metal also runs against an anvil in order to cut through the material. The heat of the blade seals the edges without burning in order to prevent the material from fraying.

The rewind section also has options. The main type is centre winding using differential rewind shafts. These shafts are becoming universal on most slitting machines. The differential shafts ensure an even tension across the full width of the material. Closed-loop control of the winding tension using feedback from load cells provides the total tension-control system required for running tension-sensitive materials. Precise and accurate tension control is the key to good roll slitting. Modern machines use AC vector drives with closed-loop feedback from AC motors. When used with the correct control algorithms, they produce excellent results with the minimum of maintenance.

Industry usage

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Roll slitting is a technique heavily used by Converters (industry). The converter industry normally refers to companies who print, coat and laminate materials. A typical converter is a company that produces flexible packaging material for packaging food. This may involve purchasing large rolls of plastic film such as biaxially orientated polypropylene (BOPP) which is then printed to the customer's design and coated with cold seal adhesive for use on high speed packaging machines. This material is printed and coated in wide, large diameter rolls for maximum efficiency. The rolls are then slit, using a slitting machine, into smaller rolls of the size to be used on the packaging machine.[4]

See also

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References

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Customer Care

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Did you know that the slitter rewinder, incorporating advanced slitting and winding solutions, plays a pivotal role in the converting industry? With its strategic design, this machine efficiently performs the slitting process and rewinding of large material rolls, transforming them into smaller, more precise rolls. These versatile machines are crucial across various sectors such as packaging, printing, converting, and material processing.

This comprehensive guide aims to provide you with insights into slitter rewinders, the slitting process, and advanced slitting and winding solutions. By covering core aspects like types, components, applications, maintenance, and purchasing essentials, including considerations for the slitting process and cutting-edge solutions, you'll gain the knowledge to make informed decisions when investing in or operating these machines. Whether you're a seasoned professional or new to the industry, this guide serves as a valuable resource for deepening your understanding of slitter rewinders and their vital role, particularly when integrating advanced slitting and winding solutions into your business operations.

1. Types of Slitter Rewinders

There are several types of slitter rewinders, each designed to handle specific materials and applications. The most common types include:

• Surface Winding Slitter Rewinder

  While the Surface Winding method is applicable to duplex shaft winding, it is primarily utilized for rewinding materials onto a single rewind shaft. This configuration is particularly suitable for handling small rolls with rapid production turns, as well as large-scale rolls like papers and nonwovens . The Surface Winding method offers notable advantages in terms of roll stability and alignment, ensuring high-quality rewound rolls.

  
  

  (Single Surface Winding Slitter Rewinder)

  
  

  (Single Shaft / Shaftless Surface Winding Slitter Rewinder)

• Turret Slitter Rewinder

  The Turret Slitter Rewinder is renowned for its innovative turret design,enabling seamless and rapid changeover between various slitting modes. A notable characteristic of a slitter equipped with turret winding is its system comprising multiple winding shafts situated on a rotating turret, allowing for uninterrupted operation. While one shaft actively winds the material, the remaining shafts can be prepared for the subsequent roll. This simultaneous operation substantially decreases downtime, enhances productivity, and optimizes the utilization of the slitter.

  
  

  (Turret Winding Slitter Rewinder for Paper)

• Two Drum Slitter Rewinder

  The two-drum slitter rewinder typically refers to a configuration where the slitting and rewinding process is carried out using two driven drums for surface winding. In this setup, the material is fed through the slitting section and then wound onto the two parallel drums, creating a tightly wound roll. The driven drums provide the necessary tension and control to ensure proper winding of the material.

  
  

  One of the key advantages of the two-drum slitter rewinder is its ability to enable high-speed operation. The driven drums facilitate efficient and precise winding of the material, allowing for increased production speeds.

  
  

  (Two Drum Sliter Rewinder for Nonwoven)

  
  

  (Two Drum Sliter Rewinder for Paper)

• Individual Arm Slitter Rewinder

  The Individual Arm Slitter Rewinder, also referred to as a Primary Slitter Rewinder, is a specialized machine used for the initial slitting and rewinding of mother rolls. This type of slitter rewinder is commonly employed in the film production industry. One notable feature is individual winders, which are positioned on a linear rail. This arrangement allows for easy adjustment based on the specific slitting specifications required. Each individual winder has its own rewind motor, enabling precise tension control for each rewinding operation. In cases where a full-width winding is necessary, a combination of motors can be utilized to handle the heavy-duty operation.

• Narrow Web Slitter Rewinder

  The narrow web slitter rewinder is a compact and space-efficient machine designed to handle narrow-width materials. One of its standout features is its doctoring capability, allowing for the reprocessing of unqualified rolls and effectively eliminating imperfections in the material. Additionally, narrow web slitter rewinders are user-friendly, thanks to the cantilevered unwind and rewind shafts that enable easy loading and unloading.

  
  

  (Narrow Web Slitter Rewinder)

• Spooling Slitter Rewinder

  Spooling Slitter Rewinders are commonly used to handle adhesive or non-adhesive materials with small slitting widths, while requiring long running length accumulation. Typically, these spooling winders have a modular design that allows for future expansion by adding an unlimited number of spooling heads. Each spooling head is equipped with its own drive and tension control, providing the flexibility to modify the spooling geometry based on specific needs, such as traverse, taper, step, and flanged winding.

  
  
  

  (Spooling Slitter Rewinder)

2. Key Components of Slitter Rewinder

A typical slitter rewinder consists of several key components :

• Unwinder unit

  This component holds the master roll and feeds the material into the slitter rewinder.

• Slitting unit

  Housing the cutting mechanism, this section performs the actual slitting of the material. It typically features adjustable slitting blades or circular knives mounted on slitting shafts or arbors. Additional cutting options, such as shear cutters, crush cutters, or razor slitting, may be included for specific requirements.

• Tension control system

  This system maintains consistent tension throughout the slitting and rewinding process, ensuring accurate winding result and preventing material damage.

• Rewinder

  The rewinder winds the slit material onto individual cores, creating the smaller, finished rolls.

• Drive system

  Comprising motors, gearboxes, and drive shafts, the drive system provides the power and control necessary for the Slitter Rewinder's operation. It drives the unwind and rewind sections, as well as the slitting mechanism, enabling synchronized and precise movement of the material during the cutting and rewinding process.

• Control panel

  The control panel allows operators to monitor and adjust various parameters, such as tension control, cutting width, speed, and other settings. It may include a touchscreen or a control console with buttons, switches, and digital displays for easy operation and real-time monitoring.

• Safety features

  To ensure operator safety and prevent accidents, Slitter Rewinders are equipped with features such as emergency stop buttons, safety interlocks, safety guards, and sensors that detect abnormalities or material jams, automatically stopping the machine to prevent damage or injury.

• Optional Features

  Depending on specific requirements, Slitter Rewinders can be equipped with additional features like automatic core loading/unloading systems, web guiding systems, integrated quality inspection systems, auto knife placement, auto web threading system, auto winder positioning and web cleaning devices, among others, to enhance productivity, accuracy, and overall workflow optimization.

  
  

  These components work harmoniously to enable efficient material processing, precise cutting, and rewinding operations in a slitter rewinder machine.

Part 1 of "5 Basic Guides of Slitter Rewinders" has provided a solid foundation for understanding these versatile machines. We explored the various Types of Slitter Rewinders and examined their Key Components, equipping you with essential knowledge to embark on your journey into the world of slitting and rewinding. Now, let's move on to Part 2, where we will delve even deeper and share additional valuable insights. 5 Basic Guides of Slitter Rewinders(Part 2)

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