The hardness of the grinding wheel refers to the bonding ability of the binder to the abrasive, not the hardness of the abrasive. The hardness of the grinding wheel is determined by the bonding strength of the binder. Under the same conditions and certain external forces, if the abrasive grains fall off the grinding wheel easily, the hardness of the grinding wheel is relatively low (or soft); conversely, the hardness of the grinding wheel is relatively high (or hard). The hardness selection of the grinding wheel has a great influence on the grinding quality and productivity. Generally speaking, the harder the part material, the softer the grinding wheel should be used. This is because the higher the hardness of the part, the faster the abrasive grains wear. Choosing a softer grinding wheel is conducive to the "self-sharpening" of the blunt grinding wheel. However, if the hardness is too low, the grinding wheel will wear quickly and it will be difficult to ensure the correct sand contour. If the hardness of the grinding wheel is too high, it will be difficult to achieve self-sharpening of the grinding wheel, which will not only reduce productivity, but also easily cause high-temperature burns on the surface of the part.
The hardness classification and code of grinding wheels include super soft (large grade, small grade), soft 1, soft 2, soft 3, medium soft 1, medium soft 2, medium 1, medium 2, medium hard 1, medium hard 2, medium hard 3, hard 1, hard 2, super hard, etc. These codes represent different hardness levels of grinding wheels, from super soft to super hard, covering a wide range of application needs. In practical applications, choosing the right grinding wheel hardness is crucial to improving processing efficiency, ensuring processing quality, and extending the service life of the grinding wheel.
In addition, the hardness of the grinding wheel also affects its self-sharpening, that is, the ability of the abrasive grains to automatically fall off after passivation, and the sharp cutting edge of the new abrasive grains in the inner layer to be put into cutting. This self-sharpening is crucial to maintaining the cutting performance of the grinding wheel. Therefore, the correct selection of the hardness of the grinding wheel is of great significance to ensure the smooth progress of the processing process and the stability of the processing quality.