Why does CNC part processing produce position error?

Why does CNC part processing produce position error?
The main reasons for the orientation error in the machining of NC parts are the machining error caused by the transmission clearance and elastic deformation in the machining process of NC parts, and the orientation error caused by the friction force that the tool head needs to overcome in the machining process. In the open-loop system, the orientation accuracy is greatly affected, while in the closed-loop servo system, the orientation accuracy mainly depends on the displacement detection.
The machining accuracy error caused by the geometric error in the machining of NC parts. In the processing of CNC machine tools, due to the influence of external factors such as external forces and heat generated in the processing process, the geometric accuracy of the machine tool is affected, and the geometric deformation of the parts processed on the machine tool will cause some errors. According to the research, there are two main reasons for machining geometric errors of CNC parts: internal factors and external factors. The internal factors that cause geometric errors in the processing of CNC parts refer to the geometric errors caused by the processing of CNC parts, such as the levelness of the CNC part processing table, the levelness and straightness of the CNC part processing guide rail, and the geometric accuracy of the CNC part processing tools and fixtures.
From the long-term data analysis and actual operation of CNC parts processing, it can be seen that the machining accuracy error caused by the positioning of CNC parts processing machine tool. From the structural point of view, the machining error of NC parts processing is mainly caused by the positioning accuracy, and the feed system of NC parts processing is the main link that affects the positioning accuracy. The feed system of NC part processing machine tool is usually composed of mechanical transmission system and electrical control system.