Your Guide to Slitter Blades

Your Guide to Slitter Blades

If you’re involved in the converting industry, you understand how important top-quality slitter blades are. Slitters are essential tools for converting soft and non-woven materials into finished products. To produce precision and professional products, leading converting companies heavily invest in the slitting knives and cutting machinery.

The American converting industry is a massive economic contributor. Just the paper converting business alone generates $400 million annually. That figure doesn’t include other non-woven fabrics like plastic film and the many materials used to produce consumer products, ranging from automotive upholstery to wall coverings.

Non-woven fabrics that slitter blades cut are web structures bonded through entangling fibers or filaments. This differs from conventionally woven materials that weave or knit fibers from yarn. By definition, non-woven materials are engineered fabrics, and they require specific knife blade technology like rotary slitting blades and circular slitter knives to ensure product quality.

High-end industrial machine knives and industrial blades are critical components in web-based material processing. Webs are the converting industry term for rolls of base materials that need to be slit or cut into smaller portions. Typical web materials are paper, synthetic cloth, plastic film and metal foil.

Investing in professional-grade industrial rotary knife blades pays an enormous return on investment when processing web products. Top-end rotary slitting blades increase intervals between knife sharpening or blade replacement, and they decrease product damage caused by dull circular slitter knives. If you’re a professional converting company, it’s vital to invest in the best slitting blades available for your specific application.

Antique Conweb Slitting Machine. This machine uses Dusenberry Style Shear Slitting Blades.

What Are Slitter Blades?

In the converting world, slitting is another word for cutting. Slitting is simply the industry term for slicing part of a web roll and turning the piece into a more manageable segment.

To avoid terminology confusion, knives and blades are interchangeable words. Both blades and knives refer to the cutting tools used in converting materials from large raw products into smaller finished units. Knives or blades are crucial components in web processing, and it’s critical they are correctly built to do the job.

Slitter blades are tools. Like any other tool, not all blades are created equal. There are many different non-woven material types converted into end-user products requiring a wide range of slitter blade designs. There is also a specialized assortment of materials used to make slitter blades for specific applications.

Most slitter blades have circular designs, meaning they are mobile and spinning cutting tools as opposed to rigid or fixed blades. Despite the standard circular design, there are options for stationary slitter blades. Slitter knife set up and profiles depend on the type of web process you use. These are the three main methods of slitter blade assembly:

  • Razor Slitting: Burst slitting or razor slitting is the simplest and fastest web cutting process. It involves a single knife or slitting blade that cuts through a material roll. The web roll can be fixed with a spinning blade severing the material at a preset location. Or, the web product can unroll through a machine while the knife blade severs the product. Razor slitting works best with thin and consistent materials like film and foil.
  • Shear SlittingShear cuts require two slitting blades. In almost all shear slitting applications, two circular knives meet at a “nip” point and cut the material much like a pair of scissors or shears would do. Shear slitting involves the top blade contacting the side of the bottom blade. Shearing works well for stationary or mobile rolls and can perform in conjunction with multiple cutting knives. Shearing action works well for thick and irregular materials like paper and plastic.
  • Score SlittingCrush slitting is another converting industry term for score slitting. This web process technique involves the knife or knives firmly contacting the base material and pressuring it against a fixed surface. Blades used in score slitting applications are blunt as opposed to being extremely sharp as with razor and shearing techniques. Score or crush slitting is not suitable for fragile products. However, scoring is ideal for cutting hard surfaces such as sheet metal.

Razor slitting, shear slitting and score slitting all have their pros and cons. Selecting a particular cutting method and the right knives for the process depends on many factors. Primarily, the material composition dictates what method and knife configuration to use. Knife and method selection also depends on the type of slitting machine in operation. These are the two common slitting machines operated in America’s converting industry:

  • Roll SlittersThese material converting equipment pieces use a large roll of base material and allow the operator to cut or slit into more manageable segments. The converting industry operates based on economies of scale. Large-volume conversion companies purchase web material stocks in massive rolls and then convert them to sub-sections or individual units. Roll slitting machines keep the stock stationary, while the cutting blade engages the work and severs it into prescribed lengths. Most roll slitters use circular knives but can use any type of blade configuration.
  • Slitter Rewinders: These converting machines have a different operating principle. Instead of keeping the roll stationary and engaging a mobile knife, slitter rewinders unroll the material on a series of rollers. Fixed knives slit the material as it passes from the main roll. The severed material passes forward onto secondary rolls where it’s rewound on individual spools. Knife blades used in slitter rewinder machines can work independently or in tandem with other slitter heads. The deciding factor is the size and quantity of slit products.

As with slitting methods, slitting machines have their pros and cons. Roll slitters are fast and easy to set up. They can handle large materials, and the machinery is relatively inexpensive. Slitter rewinders are more costly and time-consuming to operate. However, slitter rewinders are much more efficient for multiple tasks and making mass-produced, precision cuts.

Top Uses and Configurations for Slitter Blades

No matter if the machinery is a roll slitter or a slitter rewinder, it’s crucial to use the best commercially manufactured or reconditioned slitter knives or blades. It’s also essential to use the right slitter blade configurations for the particular material being cut. Here are the most common non-woven and web-based materials handled in American converting processes:

  • Paper: The most common converting material in America is paper. This versatile product converts into everything from boxes to bags. A drawback with paper converting is the dust it produces. Having the right slitting knives can help with dust control.
  • Plastic: Plastic is another main material that converts from a master roll to secondary forms. Plastic composition and thickness range from pliable products to hard and stiff goods. Knife blade materials and configuration designs need to match the particular plastic being managed.
  • Vinyl: Rolled vinyl is often slit on both roll and rewinder processes. Vinyl stock varies in weight, thickness and density. Because of the variety found in processing vinyl, the right slitter blade design has to be matched to the product, or it can affect the end product’s quality.
  • Textiles: Slitting operations commonly involve non-woven textiles. These are the engineered fabrics that long ago surpassed natural yarns and organics such as wool and cotton. Today’s textiles are advanced chemical compositions, and they require compatible slitting knives.
  • RubberThin rolls of rubber lend well to rewinder and roll slitters. Rubber has unique properties due to its inherent flexibility. Therefore, the right knife blade has to be used in rubber slitting productions.
  • Foam: Foam can be a tricky substance to slit as it crushes easily and requires precision pressure at the cutting head. Selecting the exact knife blade material, size and design can also be challenging, but it’s critical to achieve a smooth finished cut.
  • AdhesivesCutting adhesives can be a tough job as these materials tend to stick to handling equipment and the operator. To prevent getting stuck in an adhesive conversion, make sure the knife configuration easily slits through the material and freely releases.
  • FoilMetal foils fill a high demand in the food processing industry. Converting large foil rolls into wrappers requires precision cutting methods and machinery. Foil production also needs exacting performance from slitting blades to prevent tearing delicate foil products.

Slitter blade configurations are a key performance driver in the converting industry. There’s no such thing as a one-size-fits-all slitter knife or blade. Primarily, slitters have two overall styles. The most popular one is circular blade design, and the second is a straight knife approach. However, both circular and straight slitter blades have these configuration options:

  • Standard V
  • Hi/Low V
  • Vari Depth V
  • Slant Tooth
  • Scalloped
  • Double Double Sharp
  • Peg Style

Circular machine knives or slitters are optimized for razor, shear and score slitting. In addition to blade configuration design, slitter blade edges have various geometric shapes. These are the choices available for modern slitter blade edge shapes:

  • Square Edge
  • Single Bevel Sharp
  • Single Bevel Blunt
  • Double Sharp
  • Double Blunt
  • Double Single Sharp
  • Double Single Blunt
  • Double Double Sharp
  • Double Double Blunt

Outside of standard slitter blade configurations and edge styles, you always have the option of custom work. Reputable American knife manufacturers can custom design and fabricate your slitting blades to your exact specifications. They’ll work with you to assess your needs, develop prototypes and produce your desired blade with the finest knife-making materials.

Materials Used to Make Slitter Blades

Custom blade builders have access to amazing materials and know which options work best for your application. You’re not restricted to basic steel technology. Metallurgy advancements now offer you a tremendous material selection so you can match your slitter blade with the exact material to complement your configuration and edge geometry.

There are two main characteristics to look for in knife blade materials. Although the terms sound similar, there’s a vast difference in the performance of knife-making materials. These are the two primary material characteristics to be aware of:

  • HardnessThis is the knife blade material’s density, or the material’s molecular make-up and thickness. Knife blade hardness is measured on the Rockwell Scale that rates a material’s porosity and density.
  • ToughnessA blade can be extremely hard on the Rockwell Scale, but it can be volatile when it comes to standing up to wear and tear. Toughness is a material’s resistance to erosion and breakdown. Knife makers rate material toughness by its Transverse Rupture Strength (TRS).

Experienced slitting blade manufacturers thoroughly understand toughness and hardness. They strive to find the perfect balance that suits a particular application in a material converting shop. Here are the main materials you’ll find used in current knife blade manufacturing:

  • Stainless Steel: Inox steel is another name for stainless steel. This technological breakthrough is highly corrosion-resistant. Stainless steel has an exact chromium-to-carbon ratio that makes it ideal for clean converting applications like those used in the food industry.
  • High Carbon Steel: Increasing carbon content in steel alloys makes the blade harder and stronger. Knife makers carefully blend components and reduce sulfur additives that tend to induce brittleness. High carbon blades are light to medium-duty slitters.
  • Tungsten Carbide: This is an alloy containing equal parts of tungsten and carbon atoms. Tungsten carbide is much stiffer than ordinary metal bases. It’s also much denser than standard steel with a specific gravity closer to gold or lead.
  • M-2 Steel: High-speed steel (HSS) is superior in toughness than stainless, high-carbon and tungsten alloys. This material’s metallurgical designation is simply M-2, but it carries a strong reputation for durability. M-2 steels have high volumes of molybdenum, chromium and tungsten.
  • D-2 Steel: Tools like slitter blades using D-2 steel composition are highly wear-resistant but not as tough as most other alloys. D-2 has a lower tungsten volume but higher chromium content. This makes D-2 steel great for abrasive materials with low shock rates.
  • 52100 Steel: AISI alloy steel 52100 has a high carbon and chromium content. This highly durable steel blend stands up to high stress. The downside of 52100 steel is that knife makers find it challenging to mold and sharpen.
  • CPM 10V Steel: This alloy is a unique material made through the Crucible Particle Metallurgy (CPM) process. CPM 10V has vanadium in the mix as well as high carbon content. It’s exceptionally resistant to wear and has a medium hardness rating.
  • Ceramics: While ceramic slitter blades aren’t technically steel, they can be harder and tougher than many metal alloys. Ceramic slitter blades contain zirconium dioxide (ZrO2) and derive from a powder base. For extreme durability and prolonged sharpness, ceramic knife blades are an excellent investment.

Sharpening Slitter Blades

Investing in high-quality slitting blades ensures you get long-lasting and trouble-free performance. New blades from a reputable manufacturer give you immediate service and guaranteed sharpness from the moment they’re installed. However, you can also wisely invest by having your worn slitter knives professionally sharpened.

Slitter blade sharpening is a precise service provided by top American knife makers. They use a precision slitter blade sharpening machine or slitter blade grinder to reset your knife edge to its original geometry and configuration. High-quality knife makers also ensure your slitter blade material conforms to its original design.

Contact York Saw and Knife Co, Inc. for Your Slitter Blade Needs

For professional slitter blade manufacturing and sharpening, contact York Saw and Knife Co, Inc. Since 1906, we’ve designed and made slitter and other specialty knives for the American material converting industry. Our 65,000 square foot facility is conveniently located in York, PA. From here, we serve the United States market as well as foreign interests.

At York Saw and Knife Co, Inc. we also work with you to develop your custom requirements, such as a unique metal material, a special slitter blade configuration or specific edge geometry. For more information on how York Saw and Knife can make your cutting easy, call us today at 800-233-1969. You can also reach us any time through our online contact form.