The hardness of the grinding wheel is not the hardness of the abrasive wheel, but the hardness of the combination between the abrasive. Is divided into soft, soft, hard, super-hard several. Each has several levels. Hard abrasive wheel is not easy to fall off, grinding the metal scraps easily bonded to the grinding wheel, resulting in surface burns; soft abrasive wheel easy to fall off, do not burn the workpiece, but the grinding wheel consumption faster.
Grinding wheel in addition to hardness, the organizational structure is divided into tight, in a total of 12 loose, compact structure is not easy to heat.
According to your situation, you can then check the wheel speed is not low? The workpiece speed is not high?
The hardness of the wheel should be its granularity! You can see the coarser the grain size the more rough the wheel, the appearance can be seen! The larger the model number of the grinding wheel, the finer it is used to refine or to throw, the more soft and brittle! Easily damaged.