Shredder has a mispelling of sreder, sredder, schredder and schreder. In English, a shredder typically refers a paper shredder in office, but this noun has extended its meaning to industrial shredders, as shown below.
A shreder (Sreder) is used for coarse primary grinding of various materials to a fraction of 15–250 mm . Industrial schreders effectively grind large wood waste, tree roots and trunks, railway sleepers, and construction debris. They recycle car tires, solid household waste, old furniture, refrigerator cases, pallets, woodworking waste, waste paper, glass waste. Shredders are also used for processing plastics, plastic pipes, PET bottles, films, successfully shredding almost any type of existing waste.
According to their design, shredders are divided into two large groups. The first includes single-rotor (or single-shaft) shredders, usually produced complete with a hydraulic press plate. The second group includes two-rotor or four-rotor (two or four-shaft) shredders.
A single-rotor, or single-shaft, sreder is a low-speed shredder with a hydraulic ram. The single shaft sreder is designed for crushing thick waste with high resistance to crushing: corrugated cardboard, wood waste, wooden boxes and pallets, bulk polymer containers, sprues, MSW, tires. The material for grinding is fed into the shredder hopper manually or mechanically, after which it is shifted by the pre-presser to the knives – this is how the material is crushed and deformed. Further, the pieces fall under the rotor, where the knives grind them again, in addition, knives placed directly on the chamber wall also participate in the process. Subsequently, the crushed material is passed through the sieve cells and again subjected to grinding, the whole cycle is repeated until.
The size of the fraction of the final material depends on the diameter of the sieve mesh, usually 15–150 mm. The rotors of single-shaft Schreder themselves are made smooth or profiled, coated with wear-resistant alloys. The cutting blades of the shredder are attached to the rotor with screw connections. When grinding hard, abrasive or easily heated materials, the profiled rotor more evenly distributes the emerging heat from friction over the entire area of the rotor, which eliminates its overheating or sticking of raw materials and winding on the rotor.
The twin-shaft shredder, thanks to its high torque, allows you to shred almost any waste. When loading waste into the hopper, they are captured by hook-shaped knives and cutting discs mounted on two shafts moving towards each other, and crushed to the required fraction. And the side pads clean the knives, discs and ensure that the material flows down.
Four-shaft shredders are used for shredding solid waste, bulky waste, polymer waste, paper, cardboard, wood, leather and textile waste, rubber waste and even asphalt. In such a Schreder, there are two main shafts and two auxiliary shafts, equipped with special cutting discs and hook-shaped knives. Such knives begin to grind the waste and, thanks to their hook-like shape, catch the crushed material and drag it to the knives of the main shafts, which complete the grinding. The crushing of the material continues until the crushed waste particles reach such a fraction that they can freely pass into the cells of the installed sieve.