Grinding treatment is the method that receives treatment to workpiece surface with taller linear velocity with emery wheel, it is to use the abrasive on emery wheel to be excised from workpiece surface layer character actually subtle the course that cuts bits. Be machined according to workpiece exterior property, grinding divides the circle outside be grinding, inside round grinding, planar grinding a few kinds. Because grinding machines the exterior quality that gets tall treatment precision become reconciled easily, so grinding basically applies at spare parts finish machining. It can process average data not only (the steel that be like carbon, cast-iron wait with nonferrous metal) , still can process the hard data that processes hard with general metal cutting tool (if quench steel, hard alloy) . Grinding precision can amount to IT5 of IT6 ～ commonly, exterior surface roughness is Ra0 commonly.