The Mikro UMP Attrition Mill is a high speed cutting mill designed for the fine size reduction of plastics, polymers, and fibrous materials that do not respond well to other forms of impact milling. It is designed to grind heat sensitive and soft materials without liquid nitrogen or conditioned air. The raw material enters the grinding zone from a feeding device through the centrally located feed inlet. Size reduction takes place between the adjustable stator plate and high speed rotating grinding plate. The particles are reduced in size as they pass through the tapered plates. The plates have a wider gap at the center, where the material is introduced and is closest at the periphery of the plates where the material exits. The finely ground product exits the grinding zone and discharges into a product receiver. Essentially, the fineness of the product is dictated by the number of teeth on the plates, rotational speed of the rotor, and the gap between the plates.