TECHNICAL INFORMATION 158 / NORTON WINTER PRECISION TECHNOLOGY TOOL GRINDING NORTON WINTER DIAMOND CLASSIFICATION The hardness value of a material is generally influenced by the method of measurement. Different measuring methods and equipment result in different scales and units which cannot easily be compared. Thus several scales exist, for example: Moh‘s hardness: abrasion behaviour (measure of scratch resistance) Rosiwal hardness: stock removal behaviour (measure of resistance to stock removal) Vicker‘s Microhardness: indentation behaviour (resistance to penetration) In the following table, different hardness values for abrasives are given and compared to some reference materials: Diamond‘s stock removal resistance (Rosiwal hardness) is 140 times higher than corundum (alumina), even though its penetration hardness (Vickers) is only 5 times higher. MATERIAL MOH‘S HARDNESS ROSIWAL HARDNESS VICKERS MICROHARDNESS (HV) Diamond 10 140.000 10.000 cBN 9.9 9.000 Silicon carbide 9.6 2.600 Corundum 9 1.000 2.060 Quarz 7 120 1.120 Manganese 5 6.5 540 Gypsum 2 1.25 36 Talc 1 0.03 2.6 NORTON WINTER DIAMOND CLASSIFICATION GRIT SIZE [μm] D 25 40 - 60 D 20 C 34 - 45 D 20 B 25 - 37 D 20 A 20 - 30 D 15 8 - 25 D 15 C 15 - 25 D 15 B 10 - 20 D 15 A 8 - 15 D 10 6 - 10 D 7 5 - 10 D 5 3 - 7 D 3 2 - 5 D 1 0.5 - 2 D 0.7 0 - 1 D 0.25 0 - 0.5 GLOSSARY
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