The machining accuracy of CNC machine tools is ultimately guaranteed by the accuracy of the machine tool itself. The accuracy of CNC machine tools includes geometric accuracy, positioning accuracy, repeat positioning accuracy and cutting accuracy.
Geometric accuracy: also known as static accuracy, which comprehensively reflects the comprehensive geometric shape error of the key parts of CNC machine tools after assembly.
Positioning accuracy: It indicates the accuracy that can be achieved by the movement of the measured machine tool under the control of the numerical control device. According to the measured positioning accuracy value, the best workpiece machining accuracy that can be achieved in the automatic machining process of the machine tool can be judged. It refers to the gap between the actual position of the part or tool and the standard position (theoretical position, ideal position). The smaller the gap, the higher the accuracy. It is the prerequisite to ensure the accuracy of parts processing.
Repeated positioning accuracy: refers to the consistency of the position accuracy obtained by repeatedly running the same program code on the CNC machine tool. It is the consistency of the continuous results obtained by processing a batch of parts under the same conditions (on the same CNC machine tool, with different operating methods, using the same part program).
Cutting accuracy: It is a comprehensive inspection of the geometric accuracy and positioning accuracy of the machine tool under cutting conditions.
It can be seen from the above that the accuracy of CNC machine tools is divided into two aspects: mechanical and electrical, mechanical aspects such as spindle accuracy, such as runout, busbar, etc.; screw accuracy; fixture accuracy during processing, rigidity of the machine tool, and so on. Electrical aspects are mainly control methods such as semi-closed loop, fully closed loop, etc., as well as feedback and compensation methods, and interpolation accuracy during processing. Therefore, the accuracy of the machine tool does not depend on whether the machine tool is fully closed loop.