Hammer milling is a high energy process of reducing particle size (comminution) by impact with rapidly moving hammers. The material is fed into the mill’s chamber through a feed chute, typically by gravity, where it is struck by rapidly rotating hammers that strike particles repeatedly until the particles are reduced to a size that can pass through a nearby screen. Hammer mills can use “hard” or “soft” hammers for reducing particle size. Hard hammers are blunt and impact the material with a flat surface in order to smash the particle, leading to wider particle size distributions. Soft hammers use sharp, knife-like edges to cut particle, but are not as effective at particle size reduction as hard hammers.