Grinding stone is composed of three elements of abrasive bond and pore as shown in the picture above, and while rotating at high speed, it sharpens the workpiece with countless sharp abrasive grains to make the surface fine and accurate size. It is a cutting tool that makes finished products. During the grinding work with such a cutting tool, the abrasive grains are worn and new grains are spontaneously generated, and the grinding operation is repeated.