NRC Jumbo Paper Roll Slitter Rewinder

1. Key Components & Working Principle

1.1 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.

1.2 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.

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).

1.3Rewinding 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.

1.4 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.

2.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.

3.Special Considerations for Kraft Paper

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

• Effective vacuum dust extraction systems at the slitting point.

• Enclosed or shielded slitting areas.

3.2 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.

3.3 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.

3.4 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.

4. FAQs for Kraft Paper Slitting & Rewinding Machine

Q1: What are the two main slitting methods for kraft paper, and what are their key differences & applications?A1: ① Razor Slitting: Cost‑effective, suitable for lower‑grade, multi‑ply or recycled kraft where dust‑free clean edges are not critical.

② Shear (Score) Slitting: Preferred for high‑speed, high‑quality kraft paper. It delivers clean, dust‑free edges with minimal edge heat burn, and supports operating speeds of 600‑1200+ m/min.

Q2: What rewinding types are widely used for high‑speed kraft paper production, and where are they applied?A2: ① Dual‑Drum (Surface) Winder: The most common option for high‑speed kraft processing. It offers excellent tension control and produces hard, dense rolls suitable for automated packaging lines.

② Center/Shaft Winding: Adopted for special requirements such as precise torque control or pattern winding.

Q3: Why is high‑speed performance critical for kraft paper converting?A3: Kraft paper is a high‑volume, highly‑competitive commodity. Higher machine speed boosts throughput and maximizes ROI; it reduces the number of machines and operators required for the same output; it also helps converters fulfill large‑volume customer orders quickly.

Q4: What special challenges should machines address when processing kraft paper, especially recycled kraft?A4: First, dust generation: vacuum dust extraction and shielded slitting sections are required at the slitting position. Second, abrasive property: slitting blades need wear‑resistant steel like carbide‑tipped material, and rewinding drums must have hardened surfaces. Third, tension sensitivity: precise constant tension is necessary to prevent roll telescoping, wrinkled/slack edges and web breaks at high speed.

Q5: What functions does the drive and control system of a kraft slitter rewinder provide?A5: Major sections are equipped with AC vector drives or servo motors for accurate speed synchronization. A PLC with HMI touchscreen stores production recipes for different roll sizes, tension values and paper materials, enabling quick parameter switching for varied production jobs.