1, the geometric accuracy of the machining center is to ensure the basic conditions of machining accuracy. CNC machine tool geometric accuracy reflects the machine tool key mechanical components (such as bed, sliding saddle, column, spindle box, etc.) of the geometric error and its assembled geometric error, including the flatness of the table surface, the coordinate direction of movement of the mutual perpendicularity of the worktable, the worktable X, Y coordinate direction of movement of the parallelism, the spindle hole of the radial runout, spindle axial tampering, the spindle box along the z axis axis center line The parallelism of the main axis when moving in the z coordinate direction, the straightness of the spindle moving in the z coordinate direction and the perpendicularity of the spindle rotary axis to the table surface.

2、Transmission accuracy 

The transmission accuracy of the machining center refers to the relative motion accuracy between the two end pieces of the associated transmission chain in the machine tool. In the transmission chain between the spindle and the tool holder, there are errors in the gears, screws and bearings, which make the actual shift distance of the tool holder and the required shift distance have an error, and this error will directly cause the pitch error of the workpiece. In order to ensure the machining accuracy of the workpiece, not only requires the necessary geometric accuracy of the machine tool, but also requires a high degree of transmission accuracy within the contact drive chain.

3, positioning accuracy

Machining center positioning accuracy, refers to the movement of moving parts under the control of the CNC system to achieve the position and the expected position of the error between. The accuracy and the geometric accuracy of the machine tool, will have an important impact on the cutting accuracy of the machine tool, especially affecting the hole distance error in hole gap machining. 

4、Working Accuracy

Geometric accuracy, transmission accuracy and positioning accuracy is the static accuracy detected in the absence of cutting load and the machine tool does not move or movement speed is low. Due to the actual work of the vertical machining center by the cutting force, clamping force, machine tool parts and components to produce thermal deformation effects, machine tool vibration effects, the relative sliding surface of the oil film between the surface and other factors, thus affecting the machining accuracy of the workpiece.