As widely used crushing equipment, impact crusher and hammer crusher are often be compared by customers. They both have simple operation and reasonable price and there is a certain similarity from the crushing principle to the equipment structure. But, in the actual production, they have some differences. Here are the 10 differences between impact crusher and hammer crusher.
1. Different structure composition
Impact crusher is composed of rotor, blow bar, striking plate, frame, impact plate, and transmission parts and so on. The striking plate is rigidly connected to the rotor.
Hammer crusher is composed of rotor, hammer head, hammer frame, pin shaft, frame, crushing plate, sieve plate, transmission parts and so on. The hammer head is hinged on the hammer frame.
2. Different crushing cavity
The crushing cavity of impact crusher is larger, so that the material has a certain movement space, make full use of the impact effect. In contrast, the crushing cavity of hammer crusher is smaller, so the impact effect cannot be fully played. And impact crusher has multi-cavity crushing structure, making the crushing more sufficient.
3. Blow bar and hammer head (working principle)
In impact crusher, the blow bar and rotor are rigidly linked, using the inertia of the whole rotor to impact the material (free crushing, impact crushing, milling crushing), making the material not only be crushed but also get a larger speed and kinetic energy. The blow bar is from the bottom up to meet the input material for impact crushing, and throws the material up to the impact plate.
In hammer crusher, hammer head impacts the material single (free crushing and impact crushing), and the speed and kinetic energy of the material are limited. Hammer head is along the falling direction of the material to hit the material.
4. Wear resistance of the wearing parts
In impact crusher, the wear of blow bar often occurs on the side facing the material, and its metal utilization rate can be as high as 45%-48%. In the crushing of medium hard material like limestone, the blow bar wear is not serious, but in the crushing of hard material like granite, it is necessary to replace the blow bar often.
The hammer head of the hammer is in suspended state, and the wear occurs on the upper, front, back and side surfaces. Compared with blow bar in impact crusher, the wear of the hammer head is more serious. The metal utilization rate of the hammer head is about 35%, and the rotor body itself may also be worn.
In addition, if the sieve plate at the bottom of the hammer crusher is seriously worn, all the grilles need to be replaced, and the replacement of the sieve plate is also complicated.
5. Discharge opening adjustment device
The hammer crusher can only adjust the discharge opening by replacing the bottom sieve plate (new hammer crushers, such as heavy hammer crushers, generally have no sieve plate at the bottom). With the wear of the hammer head, because the sieve plate remains unchanged, the discharge opening and the final products size will not change. But in impact crusher, with the wear of blow bar, the gap between the impact plate and the rotor needs to be adjusted; otherwise the particle size will increase.
There are several ways to adjust the discharge opening of impact crusher, such as adjust the rotor speed, and adjust the gap between the impact plate and the blow bar (op bolt adjustment device) etc.
European version impact crusher can add or reduce gaskets in the lower part to adjust the gap between the third impact plate and the blow bar.
Adjustment device in impact crusher:
Adjusting the gap between the impact frame and the rotor frame can change the size and shape of the material discharged. The first and second impact plates are adjusted through the top screw adjustment device. If there is a third impact plate (European version impact crusher), it is adjusted through the gasket.
Taking decrease the discharge opening as an example: first loosen the fixing screw of the adjusting gasket, then the hydraulic cylinder moves to push the spring inside to make the spacing between the impact plate and the rotor smaller, install the outside gasket inside, and then loosen the hydraulic cylinder until the limit plate catches the gasket inside.
6. Water content requirements of materials
The feed chute and impact plate of the impact crusher can be equipped with a heating device to prevent the material from sticking, so the material with large water content can be crushed, and it is not easy to block.
Hammer crusher cannot be used to prevent the bonding of materials by heating, and cannot to crush materials with large water content.
Relatively speaking, the impact crusher is not prone to material blocking phenomenon. First, it can be equipped with a heating device to prevent the material from being blocked due to stickiness. Second, there is no grate at the bottom of the impact crusher, and the particle size of the product is determined by the gap between the impact plate and the blow bar. Therefore, when dealing with materials with large water content, impact crusher can avoid the phenomenon of blocking.
Hammer crusher is equipped with a bottom grate, which increases the likelihood of blocking.
8. Crushing ratio and products shape
Impact crusher has good final products shape. Under impact force, the material to be crushed is often broken along its fragile layer. This selective crushing method has uniform discharge particle size, cubic shape, and low content of fine powder and dust. Therefore, when cubic particles are required, for example, the anti-skid pavement of high-grade highways, impact crusher can be used as the final crushing equipment to produce concrete aggregates.
Hammer crusher has large crushing ratio, which is generally 10-25, or even up to 50. But the needle-like particle content in the final products is high and the powder content is also relatively high.
Impact crusher and hammer crusher are both suitable for crushing materials with medium hardness. Impact crusher is generally used as secondary crushing equipment, while hammer crusher is mostly used in cement production line for limestone crushing or used as primary crushing equipment in sand and gravel production plant.
On the market, advanced impact crusher frame part is three-split structure, the maintenance personal only need to open the rear shell of the crusher to replace the blow bar, impact plate, lining plate and other parts. Besides, the interchangeability of the spare parts is strong, and the variety of the spare parts is less, making it easy to purchase and management of spare parts.
Hammer crusher has many hammer heads and it takes a lot of time and manpower to replace a set of hammer heads, so that the repair and maintenance costs are high. And the replacement of the bottom sieve plate is also more troublesome.