Hammermill

The basic principle is straightforward. A hammer mill 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.

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The hammermill can be used as a primary, secondary, or tertiary crusher.

Small grain hammermills can be operated on household current. Large hammer mills used in automobile shredders may be driven by diesel or electric motors ranging from 2000 to over 5000 horsepower (1.5 - 3.7MW).

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.

Water-powered trip hammer mills were created in 488 AD by the medieval Chinese mathematician and engineer Zu Chongzhi which was inspected by Emperor Wu of Southern Qi (r. 482–493 AD).{{cite journal | title="The Water Mill" and Northern Song Imperial Patronage of Art, Commerce, and Science |journal = The Art Bulletin|volume = 84|issue = 4| publisher=CAA | author=Liu, Heping | pages=574|jstor = 3177285|year = 2002|doi = 10.2307/3177285}}Needham, Joseph (1965). Science and Civilization in China, Vol. IV: Physics and Physical Technology, p.400. {{ISBN|978-0-521-05802-5}}.{{cite book |url=https://books.google.com/books?id=d__HBAAAQBAJ&pg=PA289 |title=A History of Chinese Science and Technology, Volume 3 |editor=Yongxiang Lu |page=280 |publisher=Springer |year=2014|isbn=9783662441664 }} The water-powered trip hammer mills were powered by minor hill flowing stream that was connected to a large river beneath the high banks.{{cite book |title=Science and Civilisation in China: Volume 6, Biology and Biological Technology |editor=Needham Joseph |page=337 |publisher=Cambridge University Press |year=2000|isbn= 978-0521632621 }}

Types of Hammer Mill Crushers can include "up running" and "down running" hammer mills - {{Cite web|url=https://www.stedman-machine.com/hammer-mill-grinders.html|title=Up & Down Running Hammer Mill Manufacturer {{!}} Stedman Machine Company|last=Company|first=Stedman Machine|website=www.stedman-machine.com|language=en|access-date=2018-10-17}}

• "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 hammer mills are classified into the following types:

• Reversible hammer mill
• Non-reversible hammer mill

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. {{Cite web|last=Karma|first=Ankit|title=Hammer Mill: Types, Uses, Operating Principle, Components|url=https://www.pharmajankari.com/hammer-mill/|access-date=2021-04-23|language=en-US}}

• Blade grinder
• Trip hammer, which may be housed in a mill usually known as a forge, but which was historically occasionally described as a “hammermill.”

Category:hammer mills

Category:Chinese inventions