A comprehensive crusher is not equipped with either flying blades or hammers as a single option. Instead, it adopts a composite structure featuring spirally arranged multi-blades and heavy-duty hammers mounted on a single shaft. This is the core difference that distinguishes it from pure drum chippers which only utilize flying blades. The detailed introduction of the two components is presented below.

1. Flying Blades (Chipper Blade / Knife) – Responsible for “Cutting”

Structure: Several blades are spirally mounted on the knife roller or disc, forming a shear pair with fixed stationary blades (bottom blades and pressure plates).

Working Principle: It mainly adopts cutting and shearing forces to strip and cut wood into flake-shaped materials, similar to peeling.

Material: Alloy steel or high-carbon steel (such as Cr12MoV die steel), featuring high edge hardness and excellent wear resistance.

Characteristics: It produces neat cutting surfaces with relatively uniform particle size and low energy consumption. However, the blade edge is vulnerable to hard foreign matters such as metals and stones, and blade chipping will require integral replacement of the blade.

Wear and Maintenance: Blunt blades need sharpening. The weight difference of paired blades must meet standard requirements after sharpening, as unbalanced weight will cause equipment vibration. Blades can be sharpened repeatedly and shall be replaced when the blade thickness reaches the service limit.

2. Hammers – Responsible for “Impact Crushing & Grinding”

Structure: Hammers are flexibly suspended on a high-speed rotor with a small swing range, cooperating with the crushing chamber toothed plates and the bottom screen mesh.

Working Principle: It relies on high linear speed to generate impact force to crush materials. Materials are further ground repeatedly between the toothed plates and screen mesh to achieve fine granularity.

Material: High-manganese steel or wear-resistant hammers with hard alloy surfacing on the surface.

Characteristics: It features high impact resistance and wear resistance, capable of processing dirty materials including waste formwork and furniture with nails, iron wires and concrete residues. The disadvantages include high energy consumption, heat generation, easy screen mesh blockage, and a wider range of discharge particle size distribution.

Wear and Maintenance: Hammers are designed with a four-way symmetrical reversible structure. When one edge is worn out, the hammer can be rotated by 90° for reuse. It needs replacement after all four edges are worn out. The working efficiency will decrease significantly when hammers approach the wear limit, requiring timely replacement.

3. Cooperative Working Mechanism of Blades and Hammers (Comprehensive Crusher Core Logic)

The comprehensive crusher integrates the two working mechanisms on one shaft. The flying blades first cut and split bulky and long strip materials, and the hammers subsequently crush and grind the materials finely. Therefore, it can process waste formwork, construction waste wood, nailed furniture materials and other raw materials that cannot be handled by drum chippers, and produces finer finished materials. This is why it is widely applied in the preparation of raw materials for biomass pellets and briquette fuels.

4. Practical Application Conclusions

（1）For uniform large wood flakes used for board manufacturing, pulp production and wood shavings processing – select a pure drum chipper (equipped with only flying blades) instead of a comprehensive crusher.

（2）For fine pellet and briquette production with impure raw materials (formwork, waste furniture, nailed wood) – select a comprehensive crusher. The composite structure of flying blades and hammers is specially designed for such working conditions.

（3）Daily Maintenance Key Points: Focus on blade edge condition and weight balance for flying blades (ensure qualified weight difference after sharpening and fasten blades diagonally); regularly check hammer wear and conduct timely reversing or replacement; inspect screen mesh regularly as holes and damage will directly affect discharge particle size.