In metallurgy, mining, construction and other industrial and mining enterprises, the ore, coal, rocks and other materials have to be crushed fristly, crushing machine is the equipment used for crushing the raw materials due to manufacturers' requirements and different materials, different size requirements of the crusher of raw materials generally need to go through primary crusher, middle crushing and fine crushing three stages.
  In order to measure the size of raw materials before and after the change in the degree of fragmentation and balanced distribution of workload in various stages of crushing, crushing than the concept often cited to indicate the raw material crushing process is broken material in the crushing of money than the maximum size and the broken the maximum size ratio, ie i = D / d (D is the largest size before crushing of raw materials; d for the raw material before crushing the largest in size) were broken ratio depends on the type and structure breakers, also broken into machine the size of the block of material. generally the top stage of the broken pieces of the broken phase than 2-8 to 2-10, 10-20 crushing stage. crusher crushing different than different, according to the crusher blocks was given to material crushing force, raw materials can be roughly broken into four ways: crushed, split pieces, grinding and crushing.