TECHNICAL INFORMATION NORTON WINTER PRECISION TECHNOLOGY TOOL GRINDING / 157 GRINDING According to DIN 8589, grinding is defined as material removal using geometrically undefined cutting edges. All grinding wheels with either diamond or cubic boron nitride (cBN) are grinding tools according DIN 8589. The “cutting edges“ are composed of the diamond or cBN grit. GRINDING RATIO (G-RATIO) The grinding-ratio is calculated as a ratio of the ground workpiece volume Vw to the wheel wear volume Vs. GRINDING WHEEL BODY The body of a grinding wheel provides the static and dynamic stiffness to the tool. Dependent on the kind of grinding layer, it may consist of aluminium, filled resin, brass, steel or ceramics. The body significantly influences the vibration behaviour and the thermal conductivity of the grinding wheel; the following table shows examples for superabrasive grinding wheel bodies. GRIT SIZES The grit-sizes for diamond and cBN range according to FEPA standards (also ISO 6106) and are shown in the following table. As abrasives always contain a range of grit sizes, the values given for average grit sizes and particles per carat are approximations. D-prefix indicates diamond, while B-prefix refers to cBN. BODY MATERIAL TYPE LABEL VIBRATION ABSORPTION HEAT TRANSMISSION MECHANICAL STIFFNESS Resin with metal fillers H medium sufficient good Resin with non-metallic fillers B or D good bad satisfactory (not sufficient with thinwalled bodies) Aluminium A bad good very good Steel E bad satisfactory very good Copper C bad very good very good Composite material CFK good bad good FEPA GRIT SIZE D OR B STANDARD [Mesh] AVERAGE GRIT SIZE [μm] PARTICLES PER CT 1181 16/18 1100 60 1001 18/20 930 100 851 20/25 780 160 711 25/30 660 270 601 30/35 555 450 501 35/40 465 760 426 40/45 395 1200 356 45/50 330 2100 301 50/60 280 3500 251 60/70 233 6000 213 70/80 197 10000 181 80/100 167 16000 151 100/120 140 28000 126 120/140 118 46000 107 140/170 99 80000 91 170/200 83 135000 76 200/230 72 200000 64 230/270 63 300000 54 270/325 55 460000 46 325/400 47 750000 39 400/500 38 1400000 33 500/600 33 2100000 Norton Winter has its own classification for fine and microgrit sizes. FEPA standards are similar (M 63…M1.0).
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