Impact Crusher
There are two types of impact crushers. The Horizontal Shaft Impactor (HSI) and the Vertical Shaft Impactor (VSI). The HSI crushers break rock by impacting the rock with hammers that swing on a rotating shaft. The practical use of HSI crushers is limited to soft materials and non abrasive materials, such as limestone, phosphate, gypsum, weathered shales. HSI crushers achieve the highest degree of reduction. The VSI crushers can also break rock by impacting the material with rotating hammers, traditionally this is referred to as a "Shoe and Anvil VSI" and has similar limitations to the HSI crusher. The VSI crusher uses a different method involving a rotor with wear resistant tips and a crushing chamber designed to retain a protective layer of crushed rock for new rock to be crushed against - "rock on rock". Using this method materials with much higher abrasiveness can be crushed.
