Causes of CNC machining accuracy

In the field of machining industry, what are the reasons for the influence of CNC machining accuracy?

1. The first is the error of position influence: it usually refers to the mutual position change or deviation degree of the actual surface, axis or symmetry plane of the machined part relative to its ideal position, such as perpendicularity, position degree, symmetry degree, etc.
2. Machine error: the error of the machine itself usually refers to the dead angle error. The main causes of position error are the machining error caused by the gap and elastic deformation of the transmission in the machining process of machine tool parts, and the position error caused by the friction that the tool head needs to overcome in the machining process. In the open-loop system, the position accuracy is greatly affected, while in the closed-loop servo system, the position accuracy mainly depends on the displacement detection.
3. Geometric error: machining accuracy error caused by geometric error of CNC machining. In the process of CNC machining, the geometric accuracy of the machine tool is affected by external factors such as external force and heat generated in the process. The geometric deformation of the parts processed on the machine tool will lead to geometric error. According to research, there are two main reasons for geometric error of CNC machine tools: internal factors and external factors. The internal factors that cause the geometric errors of machine tools refer to the geometric errors caused by the factors of machine tools, such as the levelness of machine tool table, the levelness and straightness of machine tool guide rail, the geometric accuracy of machine tools and fixtures, etc. The external factors mainly refer to the geometric errors caused by the influence of external environment and thermal deformation. For example, the geometric errors caused by the thermal expansion and deformation of cutting tools or parts in the cutting process will affect the machining accuracy of machine tools and parts.
4. Cumulative error: from the long-term data analysis and actual operation of parts processing, we can see the machining accuracy error caused by CNC machine positioning. The positioning of machine tool has a great influence on the machining accuracy of NC machine tool. From the structure point of view, the machining error of CNC machine tool is mainly caused by the positioning accuracy, and the feed system of machine tool is the main link affecting the positioning accuracy. The feed system of CNC machine tool is usually composed of mechanical transmission system and electrical control system. In structural design, positioning accuracy is related to mechanical transmission system. In the closed-loop system, CNC machine tools usually can prevent the position deviation of the main parts (such as ball screw and other parts) in the feed system by positioning detection device. However, for the open-loop system, due to many factors and complex conditions, it is impossible to carry out positioning monitoring, so the machining accuracy of CNC machine tools is greatly affected.

The above explanation is the reason for the influence of CNC machining accuracy in Dongguan. I hope it will be helpful to you after reading.

ken.tang @ chengcg.com