The impact crushers are usually used as secondary or tertiary crushing purposes. IMMA also supplies a primary impact crusher to use the advantages of impact crushing. Impact crushers involve the use of impact rather than pressure to crush material. The material is contained within a cage, with openings on the bottom, end, or side of the desired size to allow pulverized material to escape.
In Horizontal Shaft Impactor, the incoming feed drops vertically through the chamber, strikes the rotating rotor or impeller bars and is fractured within the chamber. Due to this severe impacting of material, an HSI realizes up to a 20 to 1 reduction ratio. The setting of an HSI is arbitrary and depends on the curtain setting. An HSI with three curtains will tend to yield a finer dischange than one with two curtains. The main types and features of IMMA Impact Crushers are as follows