NRC Jumbo Paper Roll Slitter Rewinder Machine

This machine is designed to convert large master rolls (or "parent rolls") of kraft paper—often 1.5 to 3 meters wide and weighing over a ton—into narrower, smaller rolls of specified width and diameter for use in production (e.g., for bag making, corrugated core, wrapping, or laminating).

Key Components & Working Principle

1. Unwind Stand: Holds the master roll. High-end versions feature:

   • Automatic tension control: Critical for kraft due to its stretch variability.

   • Shaftless or shaft-type backstands: For fast roll loading.

   • Web guiding systems: Enserts the paper edge stays aligned.

2. Pre-Tension & Web Control Zone:

   • Dancer rollers or electronic tension sensors: Maintain constant, controlled tension.

   • Break/Drive Rolls: Help isolate and manage tension between sections.

3. Slitting Section (The "Heart"):

   • Razor Slitting: Uses sharp, angled razor blades pressed against a hardened steel anvil roll. Common for lower-grade, multi-ply, or recycled kraft where clean dust-free edges are less critical. Cost-effective.

   • Shear (Score) Slitting: Uses a circular upper blade that "scores" against a lower hardened steel roll. This is the preferred method for high-speed, high-quality kraft paper.

     • Produces clean, dust-free edges.

     • Minimal edge burn (heat from friction).

     • Allows for much higher operating speeds (often 600-1200+ m/min).

4. Rewinding Section:

   • Dual-Drum (Surface) Winder: The most common for high-speed kraft. The paper is wound onto cores pressed against two large, driven drums. This provides excellent tension control and produces hard, dense rolls ideal for automated packaging lines.

   • Center/Shaft Winding: Used when specific torque control or pattern winding is needed.

5. Drive & Control System:

   • AC vector drives or servo motors on each major section for precise speed synchronization.

   • Programmable Logic Controller (PLC) with a Human-Machine Interface (HMI) touchscreen.

   • Stores recipes for different roll sizes, tensions, and materials.

Why "High-Speed" is Crucial for Kraft Paper Production

Kraft paper is a high-volume, competitive commodity. Machine efficiency directly impacts profitability.

• Throughput: A machine running at 800 m/min vs. 400 m/min can process twice as much material, maximizing ROI.

• Labor Cost: Higher speed means fewer machines and operators needed for the same output.

• Market Demand: Converting houses need to fulfill large orders quickly.

Special Considerations for Kraft Paper

1. Dust & Debris: Kraft, especially recycled kraft, generates dust. Machines need:

   • Effective vacuum dust extraction systems at the slitting point.

   • Enclosed or shielded slitting areas.

2. Abrasive Nature: Kraft paper contains lignin and can be abrasive.

   • Blade Material: Slitting blades must be high-quality, wear-resistant steel (e.g., carbide-tipped).

   • Drum Hardness: Rewind drums require hardened surfaces.

3. Tension Sensitivity: Kraft has good tensile strength but can be stretchy. Precise, constant tension is vital to prevent:

   • Telescoping of finished rolls.

   • Wrinkles or slack edges.

   • Web breaks at high speed.

4. Roll Hardness & Density: Finished rolls must be uniformly hard to run smoothly on high-speed bag-making or printing machines. Dual-drum winders excel here.