Why do high-precision CNC machining centers have errors?

High-precision CNC machining center is a milling machine that automatically processes the workpiece with digital quantity sent by the digital control system as command information. In the whole digital control system, the operations such as spindle start and stop, spindle speed change, tool advance and retreat, and the relative displacement of tool and workpiece are all represented by digital, which greatly improves the stability of the whole processing process, thus improving the processing accuracy of NC milling and reducing the processing error. However, due to the accuracy of the CNC machining center itself and the control error in the machining process, the machining accuracy will decline, resulting in the phenomenon of machining out-of-tolerance. What are the factors that cause the decline of machining accuracy due to the components of the CNC machining center itself? Here is a brief introduction:

1、 High-speed motorized spindle error of high-precision CNC machining center

The spindle speed reaches more than 8000 rpm, and some high-speed CNC machining centers are more than 20000 rpm. Therefore, the configured spindle is not an ordinary spindle, but an electric spindle with high speed and high precision. The internal structure of the spindle is very complex, and the components involved are various. If you do not pay attention to maintenance during use, it is easy to have some problems. If there is too much clearance or vibration, In high-speed rotary machining, there will be large errors in the roundness and accuracy of the workpiece.

2、 Ball screw error of high-precision CNC machining center

The ball screw is the key component that directly drives the movement of the workbench. If the ball screw has free clearance and other problems, the movement of the workbench will be inaccurate, especially when the workbench is fed forward and backward, the free clearance error of the ball screw is more obvious. As a result, the positioning accuracy and repeated positioning accuracy of the workbench are deviated, which affects the machining accuracy. The supply and cleanliness of lubricating oil must be guaranteed when the ball screw is fed under load, which is the key point of inspection during normal maintenance.

3、 Servo control system error of high-precision CNC machining center

The servo control part is the power output of the whole machine tool, including the spindle drive part and the feed drive part, which are mainly composed of the driver and the AC servo motor. The main shaft drive part is the guarantee of the main shaft power output. If there is a problem in this part, it will directly lead to the decline of the main shaft accuracy. The feed drive drives the feed of the worktable through the ball screw, which directly affects the positioning accuracy and repeated positioning accuracy of the worktable after the problem occurs. If the positioning accuracy and other problems occur, there will be no machining accuracy.

4、 Guide rail error of high-precision CNC machining center

Guide rail is the carrier of worktable and workpiece, and its importance can be imagined. The guide rail type is divided into hard rail pasting and high-speed heavy-load linear guide rail. During the normal work, the quality and supply of lubricating oil must be normal. Pay attention to check the cleanness of the guide rail and prevent debris such as iron chips from scratching the guide rail surface. High-speed and heavy-load linear guide rail is widely used in some high-end CNC machining centers with high machining accuracy due to its small friction coefficient and accurate positioning. Special attention should be paid to this type of guide rail. It is necessary to control the load capacity of a single piece and not exceed the rated load capacity, otherwise it may cause damage and lead to excessive machining accuracy.