Blades for pelletizing mixed plastic wastes (MPW)
Pelletization has emerged as a promising upcycling technology, converting MPW into small, uniform pellets that can be reused in manufacturing processes.
Of plastic waste, the polymers polypropylene (PP) and polyethylene (PE) make up the largest portion. In 2022, the global market for PE and PP reached approximately 110 and 79 MMT.
The pelletizing process consists of the following steps;
- Shredding
- Cleaning and drying
- Extruding
- Cutting
For the last phase, cutting the extruded material into pellets, different methods and machinery and appropriate blades are available. To focus on blades, the undermentioned are commonly used.
Strand cut pelletizer blades: cutting of plastic strands
Granulator blades: blades for shredding plastics for further processing.
Underwater pelletizer blades: for specific (thermoplastic) materials the cutting process takes place under water
Hot die face pelletizer blades: cutting melted plastics. A challenge here can be the materials sticking to the blade, inhibiting effective cutting. Applying a non stick coating will help against excessive build up of resin on the blades.
Machines: B+B Anlagenbau, Cumberland, Erema, Gala, Munchy, Vecoplan, Weima.
Steels for pelletizer blades.
Most commonly used steels are high speed tool steels, like ASP, D1, D2,.. Tungsten carbide blades can be a good alternative when harder metals (up to 92 HRC) are suited.
