A two-shaft grinder, also called a shredder, is a machine in which the blades, which engage with each other, rotate opposite to each other, and the crushed material is torn and crushed by the shearing force between the two blades. The dual-shafts crusher is divided into two parts: the "rough crushing specification", which has a rough blade clearance and crushes as like hard plastic, metal and wood roughly, and the "shredder specification", which has a severe blade clearance and cuts soft mixed waste such as vinyl into pieces like scissors. The two-shaft grinder is suitable for mass and rough crushing. The size of output crushing depends on the gap between the attached blade and hook. It is also characterized by low noise, low vibration and less scattering of crushed material because it is crushed at low speed. There is no screen between the broken teeth and the conveyor belt. Therefore, the crushed material passes through the blade rotating in two shafts only once, and the crushed material falls from the top to the bottom, and then comes out from the conveyor belt. If you want the size to be crushed, evenly it is common to design the plant in combination with a secondary shredder with screen.

Rough crushing specification with hooks and crushed teeth

Rough crushing specifications used in pretreatment and primary crushing of wood

Wood grinders that produce chips, such as horizontal wood grinders and mobile tub grinders that rotates at high speed. Therefore, if foreign matter enters the drum, the impact on the crushing chamber or the drum can be large and cause trouble. For this reason, it is necessary to remove foreign matter as a pretreatment, and if abnormal noise occurs during crushing, the crusher must be stopped once and the crushing chamber and bit must be checked, and if necessary, the foreign matter must be removed. Pretreatment (primary crushing and rough crushing) is carried out using a low-speed rotating two-shafts crusher to prevent such trouble. It rotates at a low speed, so the impact on the teeth when foreign matter enters is small, and it can avoid troubles such as breakage. It would be better if it installed a magnetic separator. If you try to crush directly with a wood crusher such as root extraction or root stock, the crushing efficiency will be reduced. But if it is crushed firmly at low speed in primary crushing, crushing efficiency is increased. As a matter of course, the consumption of machinery used for secondary crushing is reduced, resulting in a longer life.

Rough crushing blades have a huge gap between the teeth than shredder blades, and the crushed material falls through the gap. Compared to the mono-cutter shape often used in shredder specifications, the blade has more parts made by welding, has hooks and wings, and breaks the crushed material as it is being torn.

Shredder type blade-mono cutter

Shredder for cutting various things like scissors

In the same way as shredders used to cut documents in offices, shredders are used to break down waste tires, waste plastic, construction waste, and bulky household waste. Because the blade moves at low rotation, damage to the crusher body is small and various things can be crushed. The objects to be crushed are wide, and in addition to the above, paper, carpets, fabrics, electronic products, HD documents, etc. For this reason, they are used not only at industrial waste disposal sites but also at disaster recovery sites such as earthquakes and floods.

In the shredder type, the blade is a mono-cutter (several thick circular saw teeth are passed through the shaft ) and shears, and the smaller the space between the cutters, the thinner the material can be shredded.

Self-propelled two-shafts crushers are rare in Japan.

The current state of the Japanese market is that the number of self-propelled two-shaft grinders is less than that of stationary grinders. Are the BR300S-2 from Komatsu and the ZR 900TS from Hitachi the typical models? BR300S-2 is 27 t with 182 ps. The shredder type is basic, and the rough fracture type is an option, and it's called Rarero. And ZR 900TS is 19 t and 140 PS. It covers both medium and small demand.

                     BR300S-2                                                  ZR 900TS

The two-shaft grinders can crush really various things because it can crush everything at low speed certainly. Just to give you a quick rundown, there's a ton of garbage, milk cartons, vegetables, pruned branches, wood, carpets, fabric, home appliances, computers, display cases, HD, cardboard, plastic tanks, waste plastics, videotapes, tatami mats, plastic, waste tires, non-ferrous metals, steel drums, and more. However, you should avoid metal lumps, castings such as engines, natural stones and thick iron rods.

As a tip for how to use it, there is a function (automatic inversion) to rotate the shaft in reverse to prevent the cutter from spinning without chewing the material, and to prevent too much crushed material from accumulating in the crushing chamber. Setting the appropriate reverse rotation of the shaft for the crushed material increases the efficiency of the crushing operation. The latest model has a computer function to control the rotation speed and torque of the two shafts, enabling more efficient crushing.

After daily work is completed, remove the crushed materials entangled in the shaft and blade of the 2-shaft. In particular, Especially when cutting waste materials, crushed materials may be wrapped around shafts. Even though the clearance of the shredder is severe, the edge of the blade always wears, and thin ones such as vinyl cannot be completely cut and easily get entangled. It is a system that crushed things fall down from between blades, so the amount of falling will be less if the dust wrapped around the shaft fills the gap.

Also, grease up is important. Please check if you have been properly replenished even with automatic grease replenishment. It is recommended that thorough inspection be performed on the twin-shaft crusher, which has a feature that the root on the power side of the crushing shaft and the side wall that receives it are easily subject to damage and wear. Some models are equipped with a torque plate to prevent the power load from being too much on the shaft. It is necessary to periodically check the clearance of the bleeding part.

Crushing bits wear out the most. In the case of shredder blades, check the wear and meshing of the blade every day. Compared to other environmental machines, this machine has less problems, but blade wear cannot be avoided. If the Mono Cutter gets worn out, you need to take it apart and maintain it. You need to fine-tune the clearance of the combination of dozens of blades with a few hundredths of a millimeter, so let's ask a specialist. Depending on the company, there is a case that they are developing a special knife which is harder to wear with a steel manufacturer, so if you consult with the company with know-how, you may be able to solve various problems in your work. In any case, users who don't want to work during the time it takes time and money to overhaul a monocutter type crusher seem to be rotating with another set of spare crusher sets.

In the case of rough crushing, there is no need to adjust the clearance of the meshing, but the blade itself will be severely damaged. As the wear of the tip part is repaired several times by welding, other protectors and wings are worn out, so it is necessary to remove the crushing shaft from the body and overhaul it. Cutter and wing protectors are replaced, but the wear of the shaft itself tends to be overlooked, so it is necessary to make sure that the value exceeds the manufacturer's standard.

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