The factory uses precision CNC machine tools (machining center, EDM, slow wire machine tools, etc.) for high-precision machining. Do you have such experience: when the machine is turned on every morning for machining, the machining accuracy of the first piece is often not good enough; after a long vacation, the accuracy of the first batch of parts is often very unstable, and the failure probability is very high in high-precision machining, especially the position accuracy.

Factories without precision machining experience often attribute the instability of precision to the quality of equipment. The factory with precision machining experience will attach great importance to the heat balance between ambient temperature and machine tool. They are very clear that even high-precision machine tools can obtain stable machining accuracy only under stable temperature environment and heat balance state. In the case of high precision machining production after starting up, preheating the machine tool is the most basic common sense of precision machining.

01

Why preheat the machine?

The thermal characteristics of CNC machine tools have an important impact on the machining accuracy, accounting for almost half of the machining accuracy. The spindle of machine tool, the guide rail and lead screw used in XYZ motion axis will be heated and deformed due to load and friction in motion, but the displacement of spindle and XYZ motion axis relative to the worktable ultimately affects the machining accuracy in the thermal deformation error chain.

There is a big difference between the machining accuracy of the machine tool in the state of long-time stop running and the state of heat balance. The reason is that the temperature of the spindle and each moving axis of the CNC machine tool is relatively maintained at a fixed level after running for a period of time, and with the change of processing time, the thermal accuracy of the CNC machine tool tends to be stable, which indicates that the pre-processing of the spindle and moving parts Heat is very necessary.

However, the "warm-up movement" of machine tools is ignored or unknown by many factories.

02

How to preheat the machine tool?

If the machine tool is put on hold for more than a few days, it is recommended to preheat it for more than 30 minutes before high precision machining; if the machine tool is put on hold for only a few hours, it is recommended to preheat it 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 machining axis. It is better to carry out 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, a macro program can be written on the machine tool to make the machine tool repeatedly perform the preheating action.

After the machine tool is fully preheated, the dynamic machine tool can be put into high-precision processing production, and you will obtain stable and consistent processing accuracy.