Crushing is a mechanical operation in which a force of large magnitude is applied to a relatively brittle solid material in such a direction that its failure takes place. The theory of size reduction for solids is quite complex, but can be attributed to the action of following forces acting on the particle:
- A huge compressive force exceeding the ultimate strength of the material may be responsible for size reduction as actually happens in case of jaw, gyratory and roll crushers.
- A sufficiently high impact force may be responsible for size reduction. Impact force is largely utilized in hammer & ball mills.
- Attrition, rubbing action or frictional forces may be utilized for size reduction. Such action is largely responsible for crushing in attrition mill, tube and pebble mills.
- Cutting force is utilized in knife edge mills to reduce the size of fibrous materials like mica, asbestos.
At least one or a combination of the above forces is always involved in size reduction in any crushing equipment.
