Factors Affecting CNC Precision Machining Accuracy

CNC machining is to use the automatic control system to install digital program flow commands to control the automatic start and stop, reversing and speed change of CNC machine tool bearings. CNC inserts can be selected, and the drilling amount and walking trajectory of the CNC inserts can be changed. CNC machining can reduce labor costs, improve production efficiency, and greatly guarantee product accuracy. But there is no absolute in precision, CNC machining also has tolerances, so what are the reasons that affect the accuracy of CNC machining? Jiahangaero will explain in this article.

In the actual processing and production process, there are five main factors affecting the processing accuracy.

1 The machine tool is heated up

In the process of operation, the CNC machine tool itself will generate a certain amount of heat, such as motor work, component friction and other factors, which will cause the temperature of the machine tool to rise continuously, causing components, structural systems, etc. to be adversely affected by thermal effects, such as tool displacement in the machine tool , parts wear, parts thermal expansion, circuit burnt and other phenomena, resulting in reduced machining accuracy of parts. In addition, most of the machine tools are installed in unventilated places, and external environmental conditions such as limited heat dissipation conditions will also cause temperature rise. This will increase the burden on the operation of the machine tool and reduce the precision of parts processing. In severe cases, it may cause mechanical failure and directly affect the efficiency and quality of CNC processing.

2 The error and wear of the tool itself

The cutting tool in the machine tool is also one of the processed parts. In its own production and processing process, there are geometric errors that affect the accuracy due to the limitation of processing conditions. In the process of tool installation, human operation will also affect the machining accuracy. During use, due to factors such as long-term contact between the tool and the workpiece to be processed, deformation caused by friction and high temperature, the tool will also be worn to varying degrees. Of course, when wear accumulates to a certain extent, it will also have a major impact on the accuracy of CNC machining.

3 Processing position error

Position error refers to the degree of change or offset of the actual surface, centerline or symmetrical face of the processed part relative to its ideal position, such as flatness, symmetry, symmetry, etc. The position error in CNC machine tool processing generally refers to the overcurrent protection error. The main reason for the position error is the processing error caused by the gap and elastic deformation caused by the transmission system during the machining process of the machine tool parts, and the position error caused by factors such as the sliding friction that the tool head needs to break through during the production process. In an open-loop system, positional precision suffers greatly, while in a closed-loop control steering headlight system, the key to positional precision lies in offset verification. The parts of CNC machine tools have basic error requirements such as surface, shape, radian, and relative relationship. CNC machining must complete the design requirements of the parts and meet the processing performance and quality requirements. In the process of machine tool processing, due to the influence of various factors such as transmission parts, rotary shafts, and component friction, there are deviations in the accuracy of the appearance, size, and relative relationship of parts, which reduces the accuracy of parts processing. For example, in the process of machine tool processing, errors in the swing angle of the machining axis will lead to deformation of the part shape, lower precision, and even lead to scrapping of parts in batches, which will bring significant economic losses to the enterprise.

4 Processing system error

The machine tool processing system of CNC machine tools is the part that directly implements parts processing. It is a whole that is formed by multiple subsystems and sub-components in a certain way and works together. The operation of each component will affect the processing accuracy of the entire processing system. make an impact. Therefore, the system error is constantly generated during the installation and operation of multiple components, and the error of the processing system can only be reduced as much as possible through the advancement of technology and the improvement of construction progress.

5 Deformation error

During the long-term processing and use of CNC machine tools, they will be affected by external forces, such as clamping force, gravity, friction, etc., which will cause deformation, looseness, elastic deformation, displacement and other deformation phenomena in the processing system of the machine tool, resulting in the production accuracy of the machine tool. and reduced production efficiency. Under the influence of external force, the machine tool will not only reduce the precision of production and processing, but also cause damage to the machine tool in severe cases, affecting the service life. Therefore, it is necessary to pay attention to the research on the influence factors of external force on the CNC machine tool, and reduce the influence on the machine tool.