PFP impact crushers are generally used as a primary crushers for crushing quarry rock, which are designed for crushing low abrasive and medium hard materials. The materials fed to the crusher trough its large feeding opening are crushed in two stages while impacted by the rotor's hammers to the adjustable primary and secondary impact plates.The materials will not pass to the secondary impact plate until being crushed and reduced to the size which the primary impact plate is adjusted to and will not pass to discharging chute until being crushed and reduced to the size which the secondary impact plate is adjusted to. By this adjustable impact plates the maximum size of output material can be controlled.