What distinguishes an impact crusher from a hammer crusher

Working Principle and Primary Components of Impact Crushers

Impact crushers primarily comprise a rotor assembly, front impact plate, rear impact plate, and main housing. During operation, the rotor assembly is driven at high speed via belt transmission. Falling material is subjected to impact from the blow bars, propelled towards the impact plate for further impact. Simultaneously, within the crushing chamber, material undergoes selective fragmentation through mutual collision. The front and rear impact plates subject the material to repeated impacts along a specific trajectory over time and distance. When the particle size becomes smaller than the gap between the impact plates and the impact hammers, the material is finally discharged through the outlet.

Key components of the impact crusher include springs, guard rails, front impact frame, rear impact frame, impact liners, square steel bars, impact liner bolts, cover release mechanism, main shaft, impact hammers, rotor frame, liners, locking blocks, and clamping blocks.

Working Principle of Hammer Crushers

Hammer crushers primarily rely on the impact force of hammer heads to break down materials. A screen plate is positioned beneath the rotor. Upon entering the crusher, materials are immediately subjected to high-speed impact from rotating hammers, resulting in fragmentation. Particles smaller than the screen aperture size pass through the screen plate and are discharged, while larger particles rebound. Particles striking the liner plate undergo additional impact crushing from the hammers. Throughout the crushing process, particles also collide with each other, further reducing their size. The crushed material gains kinetic energy from the hammers and impacts the liner plate on the inner wall of the machine housing at high speed, undergoing secondary crushing. Finally, the material is discharged through the screen plate (screen bars) outside the machine.

Differences Between Impact Crushers and Hammer Crushers

1.  Distinct Crushing Chambers

Impact crushers feature a larger crushing chamber with a low, wide feed opening. Material fragmentation relies not only on hammer impact but also on repeated collisions between material and impact plates or between particles themselves. This comprehensive impact crushing action more effectively breaks down large chunks. Conversely, the hammer crusher features a smaller crushing chamber with superior structural sealing. This design effectively mitigates issues such as dust contamination within the crushing space and material leakage from the machine body.

2. Differing Direction of Impact for Plate Hammers/Hammer Heads

In the impact crusher, the plate hammers meet the material from below, crushing it and propelling it onto the upper impact plate. The hammer crusher, however, strikes the material along its natural downward trajectory.

3. Differences in Wear Patterns of Consumable Parts

The impact plate and hammer head are the primary wear components for the impact crusher and hammer crusher respectively. Wear on the impact crusher's impact plate primarily occurs on the side facing the incoming material, with metal utilisation rates reaching 45%-48%. Conversely, hammer crusher hammers, suspended in a pendulum-like configuration, experience wear on their upper, front, rear, and lateral surfaces. Compared to plate hammers, hammer wear is more severe, with a metal utilisation rate of approximately 35%.

4. Different discharge adjustment methods

The lower section of the impact crusher lacks a grate screen. Product particle size is controlled by adjusting the rotor speed or diameter, modifying the distributor opening size, or regulating the grinding chamber clearance. Conversely, the hammer crusher controls particle size by adjusting the screen plate gap size. Consequently, when processing materials with high moisture content, the impact crusher avoids the issue of grate blockage during wet material crushing, offering a distinct advantage.

5. Differing Rotor Connections

The impact crusher's impact plates are rigidly connected to the rotor, meaning the plates are fixed to the rotor. During crushing, this allows full utilisation of the rotor's inertia to impact the material, not only breaking it down but also imparting significant velocity and kinetic energy. In contrast, hammer crushers employ individually suspended hammers to break material, resulting in limited velocity and kinetic energy.

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