When grinding hardened steels and tool sharpening hss conventional abrasives, in the processing zone there are significant cutting forces and high temperatures reaching the melting point processed material. This leads to poor quality of the work surface, reducing the tool life of high-speed steels. In addition, conventional abrasive wheels have a low resistance, which causes them frequent correction and readjustment. High flow rate of abrasive wheels, low surface quality, low productivity, dust the work area – the main drawbacks of conventional grinding wheels More progressive is the processing of synthetic superhard materials based on cubic boron nitride (Elbor, kubonit, hexane-A, CBN). Crystals cbn (cubic boron nitride) have increased fragile and as a result of cleaving the crystals during grinding, cutting edge is constantly being updated and thus ensured self-sharpening tool.
cbn wheels have high cutting capacity, which in some times the cutting ability of communities from conventional abrasives. High cutting power circles of the cns remains to complete wear. As well as cbn and diamond differs from conventional abrasives higher thermal conductivity and low heat capacity, which provides intensive heat removal from the grinding zone. This allows the grinding process more intensively and at the same time to receive the processed surface of the product without burns, phase and structural changes in the surface layer. No less important advantage of css is its chemical inertness in contact with different kinds of steel. Unlike diamond and silicon carbide, cbn inert to iron at temperatures up to 1200 C. This reduces the cutting force, temperature and prevents the "brining" grinding wheels. Low temperatures in the cutting circles cbn exclude the possibility formation of tensile stresses in the surface layer and, conversely, promote the formation of compressive stresses that have a positive effect on the wear resistance of workpieces and tools. see details