The factory uses precision CNC machine tools (machining centers, EDM, slow wire and other machine tools) for high-precision machining. Do you have such experience: When you turn on the machine every morning for processing, the accuracy of the first part is often not good enough; The accuracy of the first batch of parts is often very unstable, and the probability of failure in high-precision machining is extremely high, especially the position accuracy.

 

Factories without precision machining experience often attribute the instability of accuracy to equipment quality problems. For factories with precision machining experience, they will attach great importance to the environmental temperature and the thermal balance of the machine tool. They know very well that even high-precision machine tools can only obtain stable machining accuracy under a stable temperature environment and thermal equilibrium. In the case of high-precision machining and production after starting up, preheating the machine tool is the most basic common sense of precision machining.

 

 

01

Why do we need to warm up the machine?

 

The thermal characteristics of CNC machine tools have an important impact on machining accuracy, accounting for almost half of the machining accuracy. The main shaft of the machine tool, the guide rails used by the XYZ motion axis, the lead screw and other components will be heated and deformed due to load and friction during the movement, but the final impact on the machining accuracy in the thermal deformation error chain is the relative difference between the main shaft and the XYZ motion axis. Displacement of the worktable.

 

The machining accuracy of the machine tool in a long-term shutdown state and in a thermal equilibrium state is quite different. The reason is that the temperature of the spindle and each motion axis of the CNC machine tool is relatively maintained at a certain fixed level after running for a period of time, and With the change of processing time, the thermal accuracy of CNC machine tools tends to be stable, which shows that it is very necessary to preheat the spindle and moving parts before processing.

 

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

 

 

 

02

How to warm up the machine?

 

If the machine is left for more than several days, it is recommended to preheat for more than 30 minutes before high-precision machining; if the machine is left for only a few hours, it is recommended to preheat for 5-10 minutes before high-precision machining.

 

The preheating process is to allow the machine tool to participate in the repeated movement of the machining axis. It is best to perform multi-axis linkage, such as moving the XYZ axis from the lower left corner of the coordinate system to the upper right corner, and repeating diagonal lines.

 

When executing, you can write a macro program on the machine tool to make the machine tool repeatedly perform the preheating action.

 

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