Do you have such experience when using CNC wire cutting machine for high-precision machining: when you turn on the machine every morning for machining, the machining accuracy of the first piece is often not good enough; The accuracy of the first batch of parts to be machined after a long holiday is often unstable, and the probability of failure is very high in high-precision machining, especially the position accuracy.
Factories without experience in precision machining often attribute the unstable accuracy to equipment quality problems. The factory with precision machining experience will attach great importance to the environmental temperature and the thermal balance of the machine tool. They are very clear that even high-precision machine tools can obtain stable machining accuracy only under stable temperature environment and thermal balance. It is a basic knowledge of precision machining to preheat the machine tool when high-precision machining production is to be put into operation after the machine is started.
1. Why is the machine tool preheated?
The thermal characteristics of CNC machine tools have an important impact on the machining accuracy, accounting for almost half of the machining accuracy. The guideway, lead screw and other components used by the machine tool spindle and XYZ motion axis will be heated and deformed due to load and friction during movement, but the displacement of the spindle and XYZ motion axis components relative to the workbench will ultimately affect the machining accuracy in the thermal deformation error chain.
The machining accuracy of the machine tool in the state of long-term shutdown and thermal balance is quite different. The reason is that the temperature of the spindle and each moving axis of the NC machine tool is relatively maintained at a fixed level after a period of operation. With the change of processing time, the thermal accuracy of the NC machine tool tends to be stable, which indicates that it is necessary to preheat the spindle and moving parts before processing.
2. How to preheat the machine tool?
If the machine tool is put on hold for more than several days, it is recommended to preheat for more than 30 minutes before high-precision machining; If the shelving state is only a few hours, it is recommended to preheat for 5-10 minutes before high-precision machining.
The process of preheating is to let the machine tool participate in the repeated movement of the processing axis to facilitate multi axis linkage. For example, let the XYZ axis move from the lower left corner of the coordinate system to the upper right corner, and walk diagonally repeatedly.
When executing, you can write a macro program on the machine tool to make the machine tool repeatedly perform the warm-up action.
After the machine tool is fully preheated, the dynamic machine tool can be put into high-precision processing and production, and you will obtain stable and consistent processing accuracy.
