Components Of Grind Mill And Its Function. 55 known as the distribution function 45, 46 describes the distribution of fragment sizes obtained after a breakage of particles of size xj.Thus, b1j, b2j,, bnj are the mass fractions of particles in size classes 1, 2,, n after a breakage of particles in size class j.The mechanism of breakage is illustrated in 23 by a diagram shown in fig.