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Granulator blades, their benefits and how to choose suitable industrial knives


Granulator blades are industrial knives used for recycling reusable raw materials into granulate. They are part of an extensive range of recycling knives. The range also includes blades for shredding (Mewa shredders) and scrap metal recycling (Lefort scrap machines). The product assortment of Ravne granulator knives has a fly and dead and bed blades, pelletizer knives, rotor and stator knives, etc.

With much consideration and engineering know-how, they are produced for extruder and granulator machines. Tailor-made manufacturing allows for a wide array of industrial knives in numerous steel and hardness. If you were wondering why is it tailor-made, the answer is quite simple. Better quality, maximised lifetime and exceptional precision.

Custom manufacturing for specific industrial applications improves durability, optimises machine performance, adds better value in the long run and lowers the cost of ownership (TCO). Innovative technology and advanced development increased the blades' life cycle by 100%. That resulted in prolonged periods between knife replacements, lower resharpening costs and less machine downtime. 

granulator blades



How do the granulator knives function, which are their best attributes, and how were they achieved?


Granulator blades are becoming increasingly important due to environmental awareness. Understanding how our choices and behaviour impacts the environment is crucial if we want to be more environmentally friendly. That means making choices that benefit the planet rather than hurt it, and recycling represents a big part. In the last couple of years, significant changes were made, in an attempt to protect our planet by reducing pollution. Several

policies and laws to make recycling compulsory resulted in high demand for recycling industrial knives. These have an essential role in helping to reduce the clogging of trash yards and decrease the environmental pollution. They are produced from the new generation of high-alloyed tool steel combined with special heat treatment procedures. Such production assures the best ratio of hardness to safety against cracking and prevents internal defects minimising the risk of knife breakage. Granulator knives were invented to reduce the size of plastic.

Granulation is conducted in a metallic chamber connected to the motor. The process begins as the blades move and cut through a variety of plastic products swiftly and efficiently. When plastic passes through, the knives cut it into small pieces (granulate, granules). The granules are then converted to new plastic products. The best features of Ravne granulator blades are: 

  • Longer life span
  • Guaranteed Quality
  • A unique selection of materials
  • Cost-efficiency
  • Proven results
  • Consistent performance
  • Long tradition and extensive knowledge of the industry
  • Increased productivity and reduced downtime
  • Custom-made blades for different shredders such as Barclay, Wagner, Miller and Mewa shredders
  • Customisable blades for numerous granulate machines such as Profing, Wanner, Guidetti and Buss

industrial knives

How to increase granulator blades' life expectancy? 


Granulator blades are essential, yet replaceable, part of the granulating machine. To ensure a perfect recycling process, they must be correctly maintained and optimised. That will not only prolong the life but also improve the granulating process. Accurately and closely setting up the gap between blades increases the efficiency of the granulating process.

Customising blade material is necessary (in addition to adjusting the hardness level), as some applications would benefit more from other materials. The best industrial blades will balance wear resistance and toughness. It is also vital that all the knives are sharpened by a professional. Blades sharpened by someone without precision grinding experience can become hot during the process. The heat increases the hardness of the material and alters the edge toughness. 

granulator knives


Is choosing the correct industrial knives for specific industrial applications really that difficult? 


Industrial knives come in different shapes and sizes, so some industry knowledge is required. If your shredder, granulator, and extruder machine had problems in the past, you are probably wondering - is choosing the correct blade that difficult? The short answer is no. However, no matter how proficient you are, problems with lifetime, throughput or cracking can still occur. So before choosing the industrial blades, ask these questions: 

  • What kind of machine is the blade for? Is it for Mewa shedders? Maybe for Schaeffer scrap machine? Or Herbold granulator?
  • What is being shredded or granulated?
  • What is the number of blades, and how are they arranged?
  • How much material can be processed in an hour?
  • What is the feeding method (conveyor, manual, robot, etc.)?
  • What type of materials are knives made of?
  • How fine cut do you need?


The damage and longevity of the knife vastly depend on the quality of the materials and manufacturing process. SIJ Ravne Systems found the solution in the next generation of granulator knives Duralife V + Knives. With three times longer lifespan, better productivity and lower energy consumption, they are the most advanced granulator blades in the market.

Recycling operations greatly depend on the efficiency and reliability of the knives. That is why knife material, edge thickness, speed and tip angle, must be considered before choosing. Frequently shutting down the recycling process due to maintenance or changing the granulator blades is time-consuming and expensive.  

mewa shredders