FREZY TRZPIENIOWE Z WĘGLIKÓW SPIEKANYCH MOULD AND DIE INDUSTRY NORTON WINTER PRECISION TECHNOLOGY TOOL GRINDING / 145 MICRON POWDER Norton Winter micron powders consist of synthetic diamond, natural diamond and cBN with specific characteristics adapted to different industrial applications. The compounds are divided into the following types: TYPE HARD MATERIAL COLOUR SHAPE AND SURFACE Type M Synthetic diamond Greenish-yellow to pale yellow Monocrystalline, predominantly blocky, distinct cutting edges, flat cleavage planes, defined structure. Type R Synthetic diamond Greenish-grey Monocrystalline, irregular, blocky, many cutting edges, fragile structure. This type of grit is also available with metal coating. Its designation is then RC. Type P Synthetic diamond Black to dark grey Polycrystalline, blocky shapes, many cutting surfaces, no platelets, no needle-shaped particles. Type N Natural diamond Colourless to pale grey Monocrystalline, blocky to splintery, irregular, defined structure, many cutting edges. Type B cBN Black Monocrystalline, blocky, distinct cutting edges This type of grit is also available with metal coating. Its designation is then BC. MICRON POWDERS WITH METAL COATING For special applications, the use of metal-coated micron powders has proved to be advantageous, for instance in resin bond grinding wheels. Norton Winter micron powders with metal coating are available in sizes 15–25 µm, 20–30 µm and 25–37 µm. Grit size relates to the size of grit excluding the metal coating. QUALITY Due to the high quality standards Norton Winter imposes on classification, checking and packing under clean room conditions, a consistent level of grit quality is guaranteed. MEASUREMENT OF GRIT SIZE There is no universal procedure yet for determinati on of grit size. The method recommended by FEPA as ‘Standard for Diamond Micron Powder Sizes’ provides guidelines for grit size determination but they are not universally applied. Norton Winter uses optical image analysis for measuring grit size. This method permits the additional determination of the form factor (ratio of width to length of the measured particles) of the grit. The results are comparable with those obtained by FEPA. Up-to-date methods for chemical purity checking such as energy dispersive analysis (EDA) and atomic absorption spectroscopy (AAS) are also applied.
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