Rewinder Top Slitter Knives

Rewinder Top Slitter Knives

Persistools rewinder top slitter knives are precision circular cutting tools used in rewinding, slitting, and web converting equipment.

The upper knife works together with a matching bottom slitter knife. During operation, the two cutting edges are positioned with controlled overlap and side contact. As the moving web passes through the cutting zone, the material is separated by a continuous shearing action.

This cutting method is widely used for:

• Paper
• Plastic film
• Foil
• Nonwoven materials
• Tape
• Laminated web materials
• Other continuous roll products

A sharp and accurately ground upper knife helps maintain clean slit edges, stable cutting performance, and reduced material tearing during continuous production.

Dish-Shaped Top Slitter Knives

Dish-shaped knives are one of the most common upper-knife designs used in rewinder and slitter systems.

The concave profile provides the flexibility and contact geometry required for controlled engagement with the bottom knife.

These knives are commonly manufactured from:

• High-speed steel
• Tool steel
• Custom alloy steels

Depending on the application, HSS grades can provide a practical balance between sharpness, toughness, wear resistance, and manufacturing cost.

Because dish-shaped knives require controlled deformation and precision grinding during manufacturing, the concave angle is limited by blade diameter, thickness, material, and manufacturing conditions.

For Persistools dish-shaped top knives, the concave angle is generally controlled within approximately 5° maximum, depending on the specific blade design.

Flat Bevel Top Knives

Flat top knives use a simpler flat circular body with a precision-ground bevel on one side of the cutting edge.

These blades are often manufactured from solid tungsten carbide, particularly where high wear resistance and long edge retention are required.

The cutting edge can be finished through multiple grinding operations to achieve:

• Sharp edge geometry
• Consistent bevel angle
• Low cutting resistance
• Stable contact with the bottom knife
• Clean shear cutting

Because the body is flat rather than deeply dished, solid carbide becomes more practical from a manufacturing perspective.

Precision Edge Preparation

The cutting performance of a top slitter knife depends heavily on edge quality.

Important factors include:

• Blade thickness
• Outer diameter
• Bore accuracy
• Side runout
• Flatness
• Dish angle
• Bevel angle
• Edge sharpness
• Surface finish

The final cutting edge is precision ground and can be secondary-finished according to the required material and slit quality.

Matched with Bottom Slitter Knives

Top knives normally operate together with hardened-steel or TCT bottom slitter knives.

Correct matching between the upper and lower knife affects:

• Cutting-edge contact
• Side pressure
• Blade wear
• Slit quality
• Cutting stability
• Service life

Persistools can also supply matching bottom slitter knives according to the same machine, dimensions, and cutting requirements.