Hammer mill is the most widely used grinding mill and among the oldest. Hammer mills consist of a series of hammers (usually four or more) hinged on a central shaft and enclosed within a rigid metal case. It produces size reduction by impact.
The materials to be milled are struck by these rectangular pieces of hardened steel (ganged hammer) which rotates at high speed inside the chamber. These radically swinging hammers (from the rotating central shaft) move at a high angular velocity causing brittle fracture of the feed material.
Excellent design to make online or offline sterilization possible.