As a rule, the original surface flatness better jobs, uniform grinding technology, uniform grinding capacity, the processing will continue well after the surface flatness. But for the original workpiece surface flatness is poor, uniform grinding machine technology can make the flatness of the rear surface of the workpiece is also very good, it's hard to believe. Suppose that a ring-shaped workpiece before machining, flatness is poor, the outside of high low high inside the workpiece, the grinding, the workpiece is only one convex portion in contact with the abrasive and grinding away participate. Thus, in the actual grinding process, the contact between the workpiece and the abrasive is a constant diameter, increasing the outer diameter of the ring, this ring until it reaches the workpiece outer diameter, the nominal contact between the workpiece and the abrasive area not in the continuing increases. The uneven surface of the workpiece, which in the processing, is the same height as the projections on the workpiece and the abrasive surface contact points, forming a contact surface, if we can ensure that the abrasive abrasive grinding it in contact with the workpiece is formed on the surface of track density distribution, for the milling machining, the contact surface of the workpiece material are continuously uniform abrasive grinding wheelcutting off, the height of the projections are gradually decreased, so that the entire machining surface of the workpiece has a high flatness, which the principle is to grind the workpiece evenly.