What determines the accuracy of CNC machining of metal parts?

In CNC machining programming, the correct use of methods and skills is of great significance to ensure and improve the accuracy of machined parts. So what determines the accuracy of CNC machining of metal parts?

The position detection element determines the precision of CNC machining of metal parts. The position detection element is composed of a detection element (sensor) and signal processing device, which is an important part of the closed-loop servo system of CNC machine tools. Its function is to detect the actual value of the table position and speed and send the feedback signal to the numerical control device or servo device to form a closed-loop control. The detection element generally uses the principle of light or magnetism to complete the detection of position or speed.

CNC machining metal parts accuracy

According to the detection method, the position detection element is divided into direct measurement elements and indirect measurement elements. When the linear detection element is generally used to measure the linear motion of the machine tool, it is called direct measurement, and the resulting position closed-loop control is called full closed-loop control. The measurement accuracy of CNC machining metal parts mainly depends on the accuracy of the measuring element and is not affected by the transmission accuracy of the machine tool.

The linear displacement of the CNC machining table has an accurate proportional relationship with the rotation angle of the drive motor. Therefore, the method of driving the detection motor or the rotation angle of the lead screw can be used to measure the moving distance of the table indirectly. This method is called indirect measurement. Position closed-loop control is called semi-closed loop control.

The measurement accuracy of CNC machining metal parts depends on the accuracy of the detection element and the machine tool feed drive chain. The machining accuracy of closed-loop CNC machine tools largely depends on the accuracy of the position detection device. CNC machine tools have very strict position detection components, and their resolution is usually between 0.001 and 0.01mm or lower.

Compared with numerical control devices, the probability of failure of detection components is higher, and phenomena such as cable damage, component pollution, collision deformation, etc., often occur. If the detection element is suspected to be faulty, first check whether there is cable disconnection, fouling, deformation, etc. You can also judge the quality of the detection element by measuring the output. This requires skilled work on the principle of the detection element and the output signal.