Kraft Paper Roll Converting Rewinding Slitting Machine

1. What is a Kraft Paper Slitting Rewinding Machine?

It is a specialized industrial machine designed to convert large, master (jumbo) rolls of kraft paper into narrower, smaller-diameter rolls of specified width and length. The process involves slitting (cutting lengthwise) and rewinding onto new cores, making the paper suitable for end-use in various industries.

2. Key Components & Workflow

2.1 Unwind Stand:

Holds the large master roll (often up to 2,000+ mm wide and 1,500+ mm in diameter). Equipped with brakes or motors for tension control.

Tension Control System (Critical):

Maintains consistent tension throughout the process. For kraft paper, this is vital to prevent stretching, wrinkling, or breaking. Systems can be mechanical, pneumatic, or electronic.

2.2 Slitting Section:

Where the widthwise cuts happen. The two main methods for kraft paper are:

• Razor Slitting: A simple, low-cost method using razor blades. Suitable for lower volumes and lighter-weight kraft, but can produce dust and less precise edges.

• Shear (Score) Slitting: Uses a circular upper blade pressed against a lower hardened anvil roll. This produces a clean, burr-free cut and is the preferred method for most kraft paper, especially heavier grades, as it minimizes dust and offers superior edge quality.

2.3 Spreader/Rolling Bars:

Small bowed rollers that remove wrinkles and ensure flat sheet entry into the rewinder.

2.4 Rewind Shaft:

The core onto which the slit strands are rewound. Two main types:

• Center/Surface Rewind: The new rolls are driven by contact with a large drum. Simpler and good for tight, hard rolls.

• Centre Drive Rewind: Each new roll is driven independently by its own motor. Offers superior tension control and is better for handling variations in roll build or producing softer rolls.

2.5 Machine Frame & Controls:

Robust construction to handle kraft paper's weight and dust. Modern machines feature PLC controls for speed, tension, and length.

3. Special Considerations for Kraft Paper

Kraft paper has unique characteristics that influence machine design:

• Strength & Stiffness: The machine must be robust with strong drive systems.

• Abrasive Nature: Kraft paper, especially unbleached, is abrasive. Machine parts in contact (like guides and rollers) need hardened or coated surfaces for durability.

• Dust Generation: Cutting and handling kraft creates dust. Machines often have integrated dust extraction points.

• Tension Sensitivity: Too much tension can stretch or tear; too little can cause loose rolls. Precise, programmable tension is key.

• Roll Weight: Finished rolls can be very heavy. Automated unloading systems (like hydraulic arms or lifting tables) are common.

4. FAQ

Q1: Why shear slitting is preferred for kraft‑paper instead of razor‑blade slitting?

A: Kraft paper contains lots of plant fibre. Razor cutting tends to pull fibres, creating fuzzy edges and massive paper dust. Shear slitting with two‑group circular blades works like scissors, producing cleaner edges with less lint, greatly improving finished‑roll quality.

Q2: Can this machine process both thin wrapping kraft and heavy thick kraft board?

A: Yes. Blade gap, running speed and tension value can be adjusted via HMI touch‑screen. It supports multiple grammage kraft papers. Please inform us of your paper thickness range for optimum tool configuration suggestion.

Q3: What problems will poor tension control cause for kraft‑paper slitting‑rewinding?

A: Too high tension will stretch kraft paper, causing permanent deformation; insufficient tension brings loose winding, messy edges and telescoping rolls. Good tension control guarantees compact, neat finished rolls convenient for storage and secondary processing.

Q4: Is the machine able to handle jumbo mother rolls of large weight?

A: It depends on unwinding shaft load configuration. We support customized unwinding load according to customers’ jumbo‑roll weight requirements for heavy‑duty kraft‑paper production scenarios.