A hammer mill is simply a crusher that is built to shred, grind and disintegrate a wide range of materials, the technology is straightforward in that a steel drum or a chamber fitted with horizontal or vertical shafts on which free swinging hammers are mounted, at a high speed the rotor spins and with the continual rain of blows from the hammers the material is pulverized into small pieces. A perforated screen is also present, by either use of gravity or is air assisted mechanism it acts to screen the particle to a specified mesh size.
With the market full of equipment providers the user needs to carefully consider certain aspects, the system should conserve energy and be cost effective, able to produce a wide range of particle size, easy to use, work with any friable material and fibre, and with minimal maintenance needed. The manufacturer of the machine should also be able to counter the three major disadvantages of the hammer mill which are heat, noise and dust.
Hammer mills range from Small grain which can be operated on household current, to large hammer mills used in automobile shredders, driven by diesel or electric motors ranging from 2000 to over 5000 horsepower. The manual mills are mostly noisy compared to electric ones. Some crucial points to note when installing a hammer mill; the equipment before and after the hammer mill should be interlocked in the motor control centre for automatic control incase of a shut off, should have a reversing starter which allows the rotor to be changed from clockwise to counterclockwise on regular intervals and for maintenance and unexpected downtime control, a temperature monitoring system for the main shaft is recommended.