What is Material Size Reduction?
Material size reduction is the process by which a piece of material is reduced to pieces of smaller sizes. Generally, the process involves three steps: (i) shredding, (ii) granulation, and (iii) grinding. As it goes through all these steps, the material is reduced to smaller and smaller sizes until it reaches the desired dimensions.
Industrial shredders are the primary size reduction machines for waste shredding, paper recycling, plastic scrap and film, wood scrap recycling, and document and data destruction.
Industrial shredders come in various configurations, designs, and capabilities to meet all application demands. The most common arrangements are single-rotor and double-rotors, vertical or horizontal designs.
Double Rotor Shredders
Double rotor industrial shredders have opposite rotating rotors that pull the material between the two rotors. In a dual-shaft shredder, the cutters or knives cut the material when it passes over the blade and the opposing counter-knife. A dual shaft shredder creates homogenous material output.
They are best suited to shred waste material with relatively high tensile strength. They include steel and iron, bulky wood scrap, panel and millwork scrap, large plastic purges,
bulky municipal solid waste, etc.
Granulation is the process of forming grains and granules from a solid or pre-shredded material. In plastic recycling, granulation is shredding plastic objects to be recycled into flakes or pellets, suitable for later reuse in plastics extrusion.
Slow-speed plastics granulators are mainly used beside-the-press machines to grind plastic runners and sprues in injection and blow molding processes. The resulting granules are then immediately reintroduced into the production process.
In addition, beside-the-press granulators can be used for rejected products in the in-line recycling process.