Hammermill


A hammermill is a mill whose purpose is to shred or crush aggregate material into smaller pieces by the repeated blows of small hammers.

Applications

Hammermills have numerous industrial applications, including:
The basic principle is straightforward. A hammermill is essentially a steel drum containing a vertical or horizontal rotating shaft or drum on which hammers are mounted. The hammers are free to swing on the ends of the cross, or fixed to the central rotor. The rotor is spun at a high speed inside the drum while material is fed into a feed hopper. The material is impacted by the hammer bars and is thereby shredded and expelled through screens in the drum of a selected size.
The hammermill can be used as a primary, secondary, or tertiary crusher.
Small grain hammermills can be operated on household current. Large hammermills used in automobile shredders may be driven by diesel or electric motors ranging from 2000 to over 5000 horsepower.
The screenless hammer mill uses air flow to separate small particles from larger ones. It is designed to be more reliable, and is also claimed to be much cheaper and more energy efficient than regular hammermills. The design & structure of the hammermill is always determined by the end use.

History

Water-powered trip hammermills were created in 488 AD by the medieval Chinese mathematician and engineer Zu Chongzhi which was inspected by Emperor Wu of Southern Qi. The water-powered trip hammermills were powered by minor hill flowing stream that was connected to a large river beneath the high banks.

Types of hammermill crushers

Types of hammermill crushers can include up running and down running hammermills.
;Up running:Uses perforated screens or grate bars to reduce soft or hard materials. The material to be reduced determines the rotor construction that can be adjustable based on wear.
;Down running:Most suitable for fibrous materials due to the high concentration of shearing action within the unit.
Based on the director of the motor the hammermills are classified into the following types:
  • Reversible hammermill
  • Non-reversible hammermill
Although the mills are classified into the above two different types their working and grinding actions of both these types of mill are almost similar. However, their construction differs in various respects.