How to choice the hardness
The hardness of the grinding wheel refers to the firmness of the abrasive particles and adhesive on the surface of the grinding wheel. The hardness of the grinding wheel is soft, which means that the abrasive particles of the grinding wheel are easy to fall off, and the hardness of the grinding wheel is hard, which means that the abrasive particles are more difficult to fall off. The hardness of the grinding wheel and the hardness of the abrasive are two different concepts. The same abrasive can be made into grinding wheels with different hardness, which mainly depends on the properties and quantity of the bonding agent and the manufacturing process of the grinding wheel. The significant difference between grinding and cutting is that the grinding wheel has "self-sharpness". When you choose the hardness of the grinding wheel, you are actually choosing the self-sharpness of the grinding wheel. I hope that the sharp abrasive particles do not fall off too early, and do not blunt or fall off. . The general principle for selecting the hardness of the grinding wheel is: When processing soft metals, in order to prevent the abrasive from falling off prematurely, a hard grinding wheel is selected. When processing hard metals, in order to make the dull abrasive particles fall off in time, so that new abrasive particles with sharp edges and corners (ie, self-sharpening) are exposed, a soft grinding wheel is selected. The former is because when grinding soft materials, the abrasive wear of the grinding wheel is very slow and does not need to be detached too early; the latter is because when grinding hard materials, the abrasive wear of the grinding wheel is faster and requires faster Update. When fine grinding, in order to ensure the grinding accuracy and roughness, a slightly harder grinding wheel should be used. The workpiece material has poor thermal conductivity and is prone to burns and cracks (such as grinding cemented carbide). The grinding wheel used should be softer.
