Answer: it depends on the particular style of crusher. There are various methodologies based on numerous factors, including but not limited to, type of rock, size of input material, size of desired output, gradation of desired output, etc. Keeping this explanation simple, a jaw crusher is the most common crusher. Jaw crushers are most commonly used as primary crushers in rock quarries. Their slow speed, rugged frame, heavy duty design and longer lasting wear parts make jaws a most popular style of crusher. Jaw crushers are the most versatile machines due to their ability to crush nearly any type of material including, but not limited to, rocks, sand and gravel, concrete with rebar, asphalt, bricks, blocks, glass, ceramics, etc. Traditional jaw crushers produce less dust in the discharge material as well as the atmosphere. In the case of the US patented Rebel Crusher Jaw, it has maximum versatility by being able to crush nearly anything in one pass into a desirable size. In addition to sizing, the Rebel Crusher Jaw produces a product with a near perfect gradation. Gradation is a term used to describe the percentages of each size in a commingled pile of material. For example, a Rebel Crusher meeting the California DOT specifications for crushed concrete may produce 100% passing a 1″ screen with 90% passing a 3/4″ screen and only have around 10-15% fines/sand. Jaw crushers are a compaction crusher that squeeze and rub material in order to reduce the material smaller. This crushing action achieves maximum results when material is hard, abrasive and larger in size. Impact crushers are more specific application machines. They are less popular mostly due to the smaller input size of the rocks. The rocks should be softer, and there is more frequent replacing of wear parts. They have their place in the industry when the input material is softer and/or the desired output material is dust, fines or very small. Impact crushers operate at high speed and explode material that falls onto a high speed spinning rotor. This crushing action achieves maximum results when material is soft, spongy and smaller in input size. Cone crushers are secondary crushers that typically follow a primary crusher such as a jaw crusher. Cone crushers are used to further reduce material that has already been crushed by a primary crusher or is naturally small in size. Having a desired 5 to 1 reduction, cones can be used similar to jaws in crushing similar material. Cones are rugged, slower speed and are capable of efficiently crushing smaller material into even smaller more desirable sizes. Again, this is a short and simple explanation of the three most popular crushers. There are numerous factors to take into consideration when choosing the appropriate style of crusher. We’ll be happy to discuss the proper application of each machine in more detail anytime. In addition to jaws, impacts and cones, there are hammer mills, ball mills, roll crushers and a variety of unique styles that are less popular.