Stationary disc, rotating disc and mill assembly for reducing machines

A stationary disc for use in a disc mill assembly of a reducing machine, said stationary disc comprising:

• a first side having a stationary cutting surface for operative interaction with a rotating cutting surface of an opposed rotating disc;
• a second side having an air cooling surface in thermal contact with the stationary cutting surface;
• an attaching mechanism for operatively attaching the stationary disc to a housing, said housing having air inlets through an external wall, with the air cooling surface facing the air inlets and axially separated therefrom to permit air to flow between said housing and said cooling surface, and, with said stationary cutting surface arranged in facing operative interaction with the rotating cutting surface of the opposed rotating disc to reduce the input material;
• wherein, during operation, air is drawn in through the air inlets of the housing and across the air cooling surface to cool the stationary disc.

A rotary disc for use in a disc mill assembly of a reducing machine, said rotating disc comprising:

• a first rotating cutting surface for operative interaction with cutting surfaces of an opposed stationary disc;
• a second rotating cutting surface for operative interaction with cutting surfaces of the opposed stationary disc;
• wherein the rotating disc is substantially symmetrical about a central radial plane with said second rotating cutting surface substantially opposite to the first rotating cutting surface about the central radial plane;
• wherein the rotating disc is fixed to a rotating shaft in a first orientation with respect to the stationary disc with the first rotating cutting surface facing the stationary disc to reduce input material, and after the rotating cutting surface is no longer functional for reducing input material, the rotating disc is fixed to the rotating shaft in a second orientation with respect to the stationary disc with the second rotating cutting surface facing the stationary disc to reduce input material.