Replacement and maintenance of shredder blades

  • release time: 2021-05-28

The shredder's knives are wearing parts and need to be replaced. The shredder's knives are relatively expensive, so in order to use them more economically and practically, shredder manufacturers recommend that users purchase a set of spare knives when purchasing shredder equipment. When the knives need to be replaced, they can be replaced directly. Then, the worn shredder knives can be welded with wear-resistant welding rods and sharpened with a sharpener before continued use. This recycling method is economical and practical and does not delay the normal operation of the shredder equipment. It really kills two birds with one stone.



1. How to judge whether the shredder blade needs to be sharpened and maintained

When the following situations occur, sharpening is required in time.

1. When the quality of the shredder blade no longer meets the requirements;

2. When the energy consumption of the machine tool increases significantly;

3. When there is a clear crack on the edge of the cutting material;

4. When the alloy blade wear reaches 0.2mm;


Shredder Blades


2. How to replace the shredder blade

1. We disassemble the shredder box and place it on a flat ground to ensure stability.

2. Remove the closing ring of the knife box and disassemble the complete knife shaft. Due to its heavy weight, it can be tied with a lifting belt and lifted out with a crane or forklift.

3. Find the other end of the knife shaft with the pulley installed, disassemble the clamp ring on the shaft, and use a hammer and a hairpin to hit it lightly.

4. After disassembling the clamp ring, you can disassemble the knife disc piece by piece. If you encounter a situation where the blade and the shaft are tightly combined, you should first use a hammer to lightly hit the blade and the wood pad. If it still cannot move, you need to use a puller to disassemble it, find the damaged blade and replace it, and then install it as it is.

Shredder Blades


3. Precautions for replacing shredder blades

Specifications of shredder blades Various specifications of single-shaft shredders provide slitting blades, crushing blades, tearing blades, four-corner sharp knives, single-shaft machine blades, and right-angle knives.

1. The alloy head of the shredder has a sharp and sensitive edge, so during the movement, installation and removal of the blade, the alloy head must be carefully protected from damage.

2. Regularly check the radial runout and swing amplitude of the machine spindle to ensure that the shredder blades match each other.

3. Before installing the shredder blade, the debris on the spindle and flange must be removed. The surface of the flange should be flat, clean and perpendicular to the shaft.

4. Using the largest possible flange can make the saw blade run more smoothly. The size of the flange should be consistent. The size of the flange is 1/3 of the diameter of the saw blade (thin saw blades should use a 1/2D flange) for better sawing effect (especially thin blades).

5. The shredder blade should idle for 30 seconds after being installed stably, and start cutting work after confirming that everything is normal.

6. When installing the shredder blade, the flange nut must be moderately tight. If it is too loose, the saw blade will slip during rotation and cutting. If it is too tight, the saw blade will be damaged or deformed, affecting the cutting effect.

7. Before cutting, the operator of the shredder blade must wear protective equipment (protective glasses, dust masks, safety helmets, protective gloves) and check whether the saw machine protective cover is intact.



Plate shredder


4. How to replace and maintain the double-shaft shredder cutter

When the double-shaft shredder is working, the cutter is not only impacted and polished by the material, but also suffers from the wear caused by friction. Therefore, whether it is a single-shaft shredder or a multi-shaft shredder, as long as it is used, it will be affected by these two forces at the same time. Over time, the cutter will definitely wear out, and the appearance of the cutter and the edges and corners on both sides will slowly become arc-shaped.

Therefore, when the force of the double-shaft shredder is transferred and the wear effect of the cutter changes, it indicates that the service life of the cutter is about to end. When the output does not meet the requirements of the downstream production line, the cutter has failed and needs to be replaced in time for normal production.

1. Disassembly and assembly precautions

When disassembling and replacing, you need to pay attention to protecting the alloy head. Damage to the alloy head will cause serious consequences, resulting in more than necessary expenses. During the disassembly and assembly process, you need to pay attention to avoid injuries caused by sharp edges to ensure safe disassembly and assembly.

2. Inspection is essential

The first thing you need to do to maintain the shredder blade is regular inspection. Regular inspection is mainly to check the bite degree of the blade. If there is a mismatch in the bite, it must be adjusted to avoid damage to the blade. At the same time, it should be noted that the area around the blade must be kept clean before installation to avoid any debris.

3. Idle operation is essential

For the inspection of the blade, it is necessary to pay attention to the idling of 30 seconds after installation and inspection. If there is no abnormality in idling for 30 seconds, you can start working normally and cut. If there is an abnormal sound during idling, you must stop the machine for inspection.


Double shaft shredder blade


5. Repair and replacement of metal shredder parts

In order to reasonably exert the working efficiency of the machine, in addition to mastering the use of the machine, it is also necessary to update and maintain the equipment well. The following introduces the repair and replacement of metal shredder parts.

1. Repair and replacement of screen mesh.

The screen mesh is made of thin steel plate or iron sheet punching. When the screen mesh is worn or pierced by foreign objects, if the damage area is not large, it can be repaired by riveting or soldering; if the damage is large, a new screen should be replaced. When installing the screen mesh, the burr side of the screen hole should face inward and the smooth side should face outward, and the screen piece and the screen frame should fit tightly. When installing the ring screen piece, the overlap of the inner layer should be in the direction of rotation to prevent the material from getting stuck at the overlap.

2. Lubrication and replacement of bearings.

The metal shredder should clean the bearings after every 300 hours of operation. If the bearing is lubricated with engine oil, it is advisable to fill 1/3 of the gap in the bearing seat when adding new engine oil, not more than 1/2. Before operation, just tighten the oil cup cover a little. When the bearing of the crusher is seriously worn or damaged, it should be replaced in time, and attention should be paid to strengthening lubrication; when using tapered roller bearings, attention should be paid to checking the axial spacing of the bearings to keep it at 0.2-0.4 mm. If there is any discomfort, it can be adjusted by adding or removing paper pads at the bearing cover.

3. Replacement of claws and hammers.

Among the crushing parts, the crushing claws and hammers are vulnerable parts in the feed crusher, and are also the main parts that affect the crushing quality and productivity. The crushing claws and hammers should be replaced in time after wear. When replacing the claws of the claw type crusher, the disc should be pulled out first. Before pulling out, first open the round nut lock plate on the back of the disc, unscrew the round nut with a hook wrench, and then pull the disc out with a special puller. In order to ensure the balanced operation of the rotor, attention should be paid to replacing the complete set when changing the teeth, and a static balance test should be performed after the replacement to ensure the stable operation of the metal shredder. When assembling the claws, the nuts must be tightened, and be careful not to miss the spring washers. When replacing teeth, qualified parts should be selected, and the weight difference of a single tooth claw should not exceed 1.0-1.5 grams.



Double shaft shredder blade


6. Summary

When we find that the cutter seems not so easy to use, or even suddenly find that the output material changes significantly and does not meet the requirements, it means that the life of the cutter has come and a new cutter needs to be replaced. You should know that for fragile materials such as plastics and wood, the cutter can rotate faster appropriately. For materials such as waste and thin metal materials, it can also be easily completed; but when tearing some materials, the speed must be relatively slow, such as tearing woven bags, waste wires and cables, etc. Timely adjustment of the shredder cutter speed can increase the bite force, fully tear, and tear these entangled materials faster. Scientifically adjusting the speed of the shredder cutter can not only increase the output, but also avoid unnecessary wear of the cutter and extend its service life.

Therefore, we must predict in advance and replace the cutter that has been worn and can no longer work normally before it really affects the work. No matter whether it is a life-span material, constant grinding will eventually wear out. And the cutter is precisely the most critical component of the shredder. Therefore, in the daily operation of the double-shaft shredder, it is necessary to strengthen the maintenance and care of the cutter. When there is a problem with the cutter, it must be solved as soon as possible, and it is determined when it must be stopped and repaired or replaced in time.

The above is the process of how to install and disassemble the shredder blade during maintenance. If there is still something unclear, you can find the relevant installation video on our official website for learning.


Xinbei Mechanical Hard Material Shredder






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