Grinding wheel hardness and its choice

The hardness of the grinding wheel refers to the difficulty of the abrasive grains on the surface of the grinding wheel falling off under the action of grinding force. The hardness of the grinding wheel is soft, which means that the abrasive grains of the grinding wheel are easy to fall off, and the hardness of the grinding wheel is hard, indicating that the abrasive grains are difficult to fall off. The hardness of the grinding wheel and the hardness of the abrasive are two different concepts. The same kind of abrasive can be made into grinding wheels of different hardness, which is mainly determined by the performance 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”. Choosing the hardness of the grinding wheel is actually choosing the self-sharpness of the grinding wheel. I hope that the sharp grinding particles should not fall off too early, and should not be blunt or fall off. . The general principle for selecting the hardness of the grinding wheel is to use a hard grinding wheel in order to prevent the abrasive from falling off prematurely when processing the soft metal. When processing hard metals, in order to timely remove the blunt abrasive particles to expose new abrasive grains with sharp edges (ie, self-sharpness), a soft grinding wheel is used. The former is because when grinding soft materials, the working abrasive grains of the grinding wheel wear very slowly, and do not need to be detached too early; the latter is because when grinding hard materials, the working abrasive grains of the grinding wheel wear faster and need to be faster. Update. In the case of fine grinding, in order to ensure the grinding accuracy and roughness, a slightly harder wheel should be used. When the workpiece material has poor thermal conductivity and is prone to burns and cracks (such as grinding hard alloys), the selected grinding wheel should be softer.