Mill (grinding) - WikipediaIn materials processing a grinder is a machine for producing fine particle size reduction through attrition and compressive forces.attrition grinding process,comminution by the attrition (grinding - UNT Digital LibraryComminution by the attrition grinding process. (Bulletin–Bureau of Mines ; 670). Bibliography: p. Supt. of Docs. no.: I 19.3:670. 1. Size reduction of materials.