The input value of Dalian NC machining will be close to zero. Or, for other reasons, the tool should have left the workpiece but actually did not leave the workpiece and entered the workpiece. When this happens, the zero of the workpiece coordinate system should be located outside the workpiece or on the base of the workbench (or fixture), and the result will be different.

At least on the surface of the workpiece. The feed speed of CNC machine tools has increased from 16m/min in 1980s to 24-40m/min now. The spindle speed of CNC machine tools has also increased from 2500 r/min to 6000-40000 r/min. The structure of CNC machine tools has also changed from open type to closed type. In such a high speed and structure, once due to programming and operation errors, the workpiece can complete more processing content after one clamping, and the processing accuracy is higher.

For batch workpiece with medium processing difficulty, its efficiency is 5-10 times higher than that of ordinary equipment, especially it can complete many processing that ordinary equipment can not complete. It is more suitable for single-piece processing with complex shape and high precision requirement or multi-variety production in small and medium batches. The spindle of the machining center in the vertical state in space is called the vertical machining center, and the spindle in the horizontal state in space is called the horizontal machining center.

The spindle can be converted vertically and horizontally. It is called vertical and horizontal machining center or five-sided machining center, or compound machining center. According to the number of pillars in the machining center, there are single pillar type and double pillar type (gantry type). According to the number of coordinates of motion and simultaneous control of the machining center, there are three axes, two axes, three axes, four axes, five axes, four axes, six axes and five axes.

The difference between CNC milling machine and CNC milling machine is that CNC machining center has the function of automatic tool exchange. Tools for different purposes are installed in the tool library. After the workpiece is clamped, the machining tool on the spindle is changed by changing the tool to realize various processing functions. The main points of overhaul operation are: before processing, the processing technology should be determined, the content of the process card should be clarified, especially the shape of the parts to be processed, and the content of the next processing procedure should be known.