Contents :
- Principal of Hammer Mill
- Construction of Hammer Mill
- Hammer Mill Diagram
- Hammer Mill Working
Hammer Mill
Principle of Hammer Mill :
Size reduction is achieved by impact and attrition.
Construction of Hammer Mill:
• The hammer mill consists essentially of a high speed rotor turning inside a cylindrical casing. The rotor is mounted on a shaft which is usually horizontal. The swing hammers are pinned to a rotor disk. The hammers are rectangular bars of metal with plain or enlarged ends. In this mill, the particles are broken by the sets of swing hammers. The product falls through a grate or screen which forms the lower portion of the casing.
• Several rotor disks each carrying four to eight swing hammers are often mounted on a single shaft. The rotor disk diameter ranges from 150 mm to 250 mm. As the hammers are hinged, the presence of any hard material does not cause damage to the equipment. The hammers can be readily replaced when they worn out.
Hammer Mill Working Principle:
• The material to be crushed is fed from the top of the casing. The shaft is rotated at a high speed and centrifugal force causes the hammers to swing out radially. The material is beaten by the hammers around inside of the casing and by impact against the breaker plates (located on inside of the casing) or the screen is crushed until it is small enough to fall through the screen.
• Hammer mills are employed to grind tough fibrous solids like bark or leather, steel turnings, hard rock, sticky clay, etc.
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