Analysis of friction coefficients in a vibrating cup mill (ring mill) during grinding

Abstract This work describes how a ring mill is used as a friction coefficient analysis system for granular materials during grinding. This assessment method was mainly created to analyse energy consumption in comminution processes in friction mills. A ring mills consists of a cylindrical jar containing the grinding masses as coaxial cylinders and rings, made from high strength materials, moved by an oscillating movement caused by eccentric masses arranged on the mill motor axis. Inside the jar the masses rotated by the jar's eccentric oscillation rotate freely, at a speed that depends on the friction between the grinding bodies and the jar's inner surfaces. The work checked how the grinding masses rotate, the mechanism causing coupling and the relations between these movements and the friction coefficient. With this model it is possible to measure grinding energy consumed instant by instant and the energy lost through heat and average pressure generated by the thrust of the grinding masses; and, lastly, the friction coefficient between the mass and the material interposed.