Take a look around—you'll find roll slitting at work everywhere. The packaging on your snacks, the labels on bottles, the insulation inside appliances, and even the foil in electronics all start as large rolls of material. But before they become the neatly cut sizes you see in everyday products, they need to be precisely sliced down from massive rolls into smaller, usable widths.

That's where roll slitting comes in. It's a key manufacturing process that helps industries cut large rolls of paper, plastic, film, or metal foil into the exact sizes they need. Without roll slitting, these materials wouldn't be as easy to use or apply in production.

So, how does roll slitting work? Let's break it down.

What is Roll Slitting?

Roll slitting is the process of cutting large rolls of material into narrower, more usable strips. Many industrial materials—such as paper, plastic film, adhesive tape, and metal foil—are manufactured in wide rolls, which are too large to be used directly. To make these materials suitable for different applications, they need to be precisely cut into smaller widths. This is where roll slitting comes in.

This process is widely used in packaging, printing, electronics, and automotive manufacturing. For example, the plastic wrap around packaged food, the labels on bottles, and the insulation inside electronics all start as large rolls that must be slit down to the right size. Slitting ensures that materials are evenly distributed, properly sized, and ready for further processing or direct use.

To achieve precise cuts, slitting machines use specialized blades that carefully slice through the material while maintaining quality, accuracy, and efficiency. Depending on the material and application, different slitting methods are used to achieve the best results. Now, let’s take a closer look at the two main types of roll slitting and how they compare.

Log Slitting vs Rewind Slitting

Different materials require different slitting methods based on speed, precision, and handling requirements. The two most common approaches are log slitting and rewind slitting, each suited for specific applications.

While this overview highlights key differences, understanding how each method works provides deeper insight into their advantages and limitations.

1. Log Slitting

Working Principle

The roll is placed on a mandrel and rotated at high speed while a circular blade moves in to make the cut. The blade shifts to the next position after each slice.

Strengths

Log slitting offers high-speed processing since it eliminates the need for unwinding and rewinding. The equipment is generally compact and cost-effective, making it suitable for operations with limited space.

Limitations

Because the blade cuts through the entire roll at once, precision is lower than in rewind slitting. The cutting process can cause rough edges or wrinkles, and the blade must be frequently replaced to maintain quality. Additionally, roll size is limited by the distance between the mandrel and the blade.

Applications

This method is best suited for adhesive tapes and films, where speed is more important than precision. However, it is less effective for materials requiring smooth edges or controlled tension.

2. Rewind Slitting

Working Principle

The material is first unwound, then slit into strips using rotary or razor blades, and finally rewound onto separate cores. Since the roll is processed layer by layer, there is no limitation on roll size, unlike log slitting.

Strengths

This method provides high cutting accuracy and better tension control, which helps prevent wrinkles, misalignment, and edge imperfections. It is particularly effective for delicate or high-value materials that require precise and consistent cuts.

Limitations

Rewind slitting is a slower and more complex process than log slitting. It requires more floor space, higher equipment costs, and careful maintenance to ensure proper tension and blade alignment.

Applications

Commonly used for synthetic films, metallic foils, EMI shielding films, and large paper rolls, rewind slitting is ideal for industries that demand clean cuts and precise tolerances. Selecting the right cutting knives also plays a crucial role in achieving optimal results, which we'll explore next.

Choice of Knives in Rewind Slitting

In rewind slitting machines, two primary types of knives are used: razor slitting and shear slitting. Razor slitting employs stationary razor blades to slice through the material, whereas shear slitting utilizes rotating circular blades that cut in a scissor-like action.

1. Razor Slitting

Razor slitting is a high-speed method known for its simplicity and precision. It uses thin, sharp blades that produce minimal material waste while delivering clean, precise cuts with little dust generation. This method is particularly suited for thin, flexible, and delicate materials such as plastic films, paper, foil, and laminated sheets. Razor slitting can be performed using two different methods: "razor in air" and "razor in groove".

Razor in Air

In razor in air, the blade cuts through the material without any lower support, making it a straightforward and efficient cutting approach. However, this method can result in slight variations in the cutting line if the material is not properly tensioned.

Razor in Groove

In contrast, razor in groove provides a dedicated groove in the lower roller, which helps secure the material and guide the cutting line, ensuring greater precision and stability. The groove also helps reduce blade wear by offering a controlled contact point.

2. Shear Slitting

For rigid, thick, and fibrous materials, shear slitting is the preferred choice due to its greater cutting power. It uses two rotating circular knives, with one positioned above and the other below the material, creating a scissor-like shearing action. Proper tension control is essential in shear slitting to achieve clean, precise edges and prevent material deformation. Shear slitting can be further divided into tangent slitting and wrap slitting.

Tangent Slitting

In tangent slitting, the material only makes contact with the topmost tangent point of the bottom knife. This method is typically used for stiff or non-bending materials that cannot conform to a curved cutting path.

Wrap Slitting

In contrast, wrap slitting allows the material to wrap around the bottom knife, ensuring consistent pressure and cutting stability. However, wrap slitting is not ideal for rigid materials, as one side of the material may bend or deform during the process.

Choice of Shearing Knives

Shearing Knives with a Shafted Knife Holder

The choice of shearing knives is crucial in rewind slitting, as it determines the adjustability of the cant angle (toe-in angle) and overall cutting efficiency. Shearing knives with a shafted knife holder, also known as a fixed-angle holder, maintain a pre-set cutting angle, ensuring consistent performance across high-speed production lines. While highly stable, this setup lacks flexibility for different material requirements.

Shearing Knives with a Pneumatic Knife Holder

In contrast, shearing knives with a pneumatic knife holder allow adjustments to the cant angle, offering greater flexibility to optimize cutting for different materials. This configuration is particularly useful in varied production environments, where precision and edge quality are top priorities.

Selecting the appropriate shearing knife and holder combination ensures optimal slitting performance, whether the goal is high-speed precision cutting or robust shearing for tougher materials.

Conclusion

Selecting the right slitting method is crucial for optimizing precision, efficiency, and material handling. Log slitting is a fast and cost-effective method that works well for adhesive materials, but it has limitations in cutting accuracy and the size of rolls it can process. Rewind slitting, on the other hand, offers greater precision and flexibility, making it the preferred choice for synthetic films, metallic foils, and large-scale production. Choosing between razor or shear slitting and shafted (fixed angle) or pneumatic (adjustable angle) knife holders further enhances performance.

For high-efficiency slitting, we recommend the Yoden Turret Slitter, which supports both razor and circular knives. It also offers an optional pneumatic circular knife automatic positioning system for precise and efficient adjustments. Contact us today to find the perfect slitting machine for your converting needs!