There are many types of grinding wheels. According to the abrasives used, it can be divided into ordinary abrasives (corundum and silicon carbide, etc.) grinding wheels and natural abrasive superabrasives and (diamond and cubic boron nitride, etc.) grinding wheels; according to the shape, it can be divided into flat grinding wheels, beveled grinding wheels, cylindrical grinding wheels, Cup-shaped grinding wheel, dish-shaped grinding wheel, etc.; according to the binder, it can be divided into ceramic grinding wheel, resin grinding wheel, rubber grinding wheel, metal grinding wheel, etc. The characteristic parameters of the grinding wheel mainly include abrasive, particle size, hardness, bond, shape, size, etc. Since the grinding wheel usually works at high speed, the rotation test (to ensure that the grinding wheel will not break at the working speed) and the static balance test (to prevent the vibration of the machine tool during operation) should be carried out before use. After the grinding wheel has been in operation for a period of time, it should be dressed to restore the grinding performance and correct geometry.

Abrasive particle size

Mainly related to surface roughness and productivity. During coarse grinding, the grinding allowance is large, and the required surface roughness value is relatively large, so coarser abrasive grains should be selected. Because the abrasive grains are coarse and the pores are large, the grinding depth can be larger, and the grinding wheel is not easy to block and generate heat. During fine grinding, the allowance is small, and the roughness value is required to be low, so finer abrasive grains can be selected. Generally speaking, the finer the abrasive grain, the better the grinding surface roughness. [1]

Hardness and its selection

The hardness of the grinding wheel refers to the firmness of the abrasive grains and adhesive on the surface of the grinding wheel. 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, which means 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 abrasive can be made into grinding wheels with different hardness, which mainly depends on the performance and quantity of the bond and the manufacturing process of the grinding wheel. The significant difference between grinding and cutting is that the grinding wheel has "self-sharpening". Choosing the hardness of the grinding wheel is actually choosing the self-sharpening of the grinding wheel. It is hoped that the sharp abrasive grains will not fall off too early, and they will not fall off after being blunted. . 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, use a hard grinding wheel. When processing hard metals, in order to timely remove the blunt abrasive grains to expose new abrasive grains with sharp edges (that is, self-sharpness), soft grinding wheels are selected. The former is because the working abrasive grains of the grinding wheel wear slowly when grinding soft materials and do not need to be detached too early; the latter is because the working abrasive grains of the grinding wheel wear faster when grinding hard materials and require faster renew. When fine grinding, in order to ensure the grinding accuracy and roughness, a slightly harder grinding wheel should be selected. The workpiece material has poor thermal conductivity and is prone to burns and cracks (such as grinding carbide, etc.), the selected grinding wheel should be softer. [2]