Failure Of Processing Accuracy? Forgotten Machine Warm Up!

The factory uses precision CNC machine tools (machining centers, EDM, slow walking and other machine tools) for high-precision machining. Do you have such experience: every morning when the machine is turned on for processing, the accuracy of the first piece 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 blame the cause of this unstable accuracy on equipment quality issues. And factories with precision machining experience attach great importance to the ambient temperature and the thermal balance of the machine tool. They are very clear 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 production after starting up, preheating the machine tool is the most basic precision machining common sense.

1.Why do you 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, screw rods and other parts used by the XYZ motion axis will be heated and deformed during the movement due to the load and friction. However, it is the relative relationship between the main axis and the XYZ motion axis component that ultimately affects the machining accuracy in the thermal deformation error chain Displacement of the table.

There is a large difference between the machining accuracy of the machine tool when it is stopped for a long time and the state of thermal equilibrium. The reason is that after the CNC machine tool spindle and each movement axis have been running for a period of time, the temperature is relatively maintained at a fixed level, and With the change of processing time, the thermal accuracy of CNC machine tools tends to be stable, which shows that it is necessary to preheat the spindle and moving parts before processing.

However, the preparation process of the machine's "warm-up movement" has been ignored or unknown by many factories.

2.How to warm up the machine?

If the machine is left for more than a few 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 position to the upper right corner position of the coordinate system and repeatedly walking diagonally.

During execution, a macro program can be written on the machine tool to allow the machine tool to repeatedly execute the preheating action.

After the machine is fully warmed up, the dynamic machine can be put into high-precision machining production, and you will get stable and consistent machining accuracy.