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How to choose an industrial knife to suit the requirements of your production line?

Jak dobrać nóż przemysłowy do wymagań linii produkcyjnej?

How to precisely select an industrial knife to suit the requirements of your production line?

Choosing the right industrial knife is a key factor in determining the efficiency, quality, and operating costs of a production line . Proper geometry, the right steel, and selecting the right knife for a specific process translate into blade durability, lower energy consumption, and production stability.

Regardless of whether you are looking for a knife for a paper cutter , knives for foils and plastics , or knives for chippers in the woodworking industry , the principles of correct selection remain unchanged - they are based on the analysis of the material, loads and design of the machine .

Below we present a complete guide that will make it a little easier to choose an industrial knife for each technological line.

Selecting steel for an industrial knife – the foundation of durability and cutting quality

The fundamental parameter in choosing an industrial knife is the type of material to be cut . This determines what type of steel we need: more abrasion-resistant, more impact-resistant, or the sharpest possible.

Different industries require completely different blade properties.

1. Woodworking industry – knives for chippers and linear wood cutting processes

Wood processing in drum and disc chippers places exceptionally high demands on the knives. Unlike planer knives (HSS or HM), chipper knives are made of high-alloy tool steels suitable for:

  • high abrasion resistance,

  • work under high impact loads,

  • stability in continuous linear operation.

The most commonly used grades include steel type 1.2360 or 1.2379 (popular name NC11LV in Poland) , usually hardened to 54–58 HRC , which provides a compromise between hardness and resistance to chipping.

Important:
Wood chippers do NOT use standard HSS knives or knives with brazed carbide plates - such solutions are typically used in planers and thicknessers.

Why is the right choice of steel crucial?

  • too hard steel → risk of breakage when hitting a foreign body (e.g. nail, stone),

  • too soft steel → quick dulling and need for frequent sharpening,

  • incorrect geometry → excessive engine load and decreased chipping efficiency.

That is why woodworking plants use specialized chipper knives , adapted to the specific machine model and the dimensions of the knife socket.

2. Recycling and plastics industry – high impact knives

In recycling, where hard, flexible or contaminated materials are processed, knives must have completely different properties than in the woodworking industry.

The priority here is:

  • high impact strength,

  • resistance to impacts on metal and other hard inclusions,

  • maximum material ductility,

  • appropriate cutting edge geometry for granulating or shredding.

Knives that are too hard could break when in contact with a steel element in the waste.

That is why dedicated knives are used for the recycling industry , whose composition and heat treatment optimize resistance to cracking, protecting the machine.

The right choice of recycling knife directly affects:

  • machine operation safety,

  • protection of the rotor and drive system components,

  • blade life and line stability.

3. Printing and packaging industry – cutting precision above all else

In the printing industry, the most important things are:

  • perfect straightness,

  • cutting surface quality,

  • fine-grained steel enabling perfect sharpening.

Slicing knives (e.g. POLAR, WOHLENBERG, PERFECTA) are made of special tool steels additionally equipped with an HSS insert or a carbide insert in a gradation appropriate for:

  • paper cutting,

  • cardboard,

  • packaging materials,

  • foil.

Errors such as edge dusting, fraying, or cutting gradients are most often caused by poor blade quality or the sharpening process. Therefore, both the selection of a printing knife and the grinding shop that refinishes the knives MUST be appropriate.

At GRAFS, we've been sharpening slicing knives for 14 years – that's where we started. For the sharpening process to be truly professional, the grinding facility must meet several key requirements:

  • use appropriate, high-quality grinding wheels (selected in terms of grit, type, diameter and nature of work),

  • ensure the proper operating parameters of the grinder - feed speed, infeed value and, what is extremely important, the rigidity of the entire machine structure ,

  • maintain the proper concentration and quality of the coolant,

  • have an experienced grinder who can use the full potential of the equipment. :)

Knife geometry – one of the most important factors in the cutting process

The material of the knife is one thing, but the shape and geometry of the blade also determine its effectiveness.

Depending on the process:

1. Guillotine cutting (paper, foil, cardboard, plastics):

  • requires perfect straightness,

  • uniform hardening/hardness along the entire length,

  • sharpening angle adapted to the type and thickness of the material.

2. Disc cutting (foils, tapes, nonwovens):

  • perfect balance is key,

  • concentricity protects against vibrations,

  • Surface smoothness improves cutting quality.

3. Shredding cutting (recycling, grinding, granulation):

  • the most important thing is the angle of attack and the profile of the blade,

  • the geometry must be adapted to the type of material: hard, flexible, brittle or contaminated,

  • The optimally selected angle results in lower energy consumption and longer knife life.

A good industrial knife is just the beginning

Even the most advanced knife will not function properly without:

  • professional sharpening,

  • flatness control,

  • regular regeneration,

  • proper assembly.

That's why at GRAFS we offer:

  • machines for sharpening industrial knives (GR, SR, CG models),

  • industrial knives for the woodworking, printing and recycling industries ,

  • technical advice based on over 14 years of experience in sharpening and manufacturing solutions for industry.

Choosing the right knife is an investment in efficiency, cutting quality and trouble-free operation of your production line .

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