Sizes Of Plates Of Grinding Machine. Abrasives grit size depends on ball dimension and the process requirements. ball size [mm] abrasive grit size (fepa-f) grade structure 4 -9 sc 220, 280 x, z 7, 9 9 - 14 sc 220 and 150 x, z 5, 9 14 - 20 sc 180 and 150 x, z 5, 9 20 - 60 sc 150 and 120 x, z 9 60 - 80 sc 150 and 120 t, v, x 9 other grain combinations are available upon request..