CNC machine tools are now widely used in the processing of variety and large quantities of parts. Due to their strong stability, high precision and high efficiency, they have replaced the original ordinary machine tools. At the same time, CNC milling machines and CNC lathes are configured on a large scale to the automatic production lines of various products to realize automatic management. However, in production, due to the failure of the servo system of the CNC machine tools, the X-axis, Y-axis and Z-axis of the CNC milling machine will move rapidly at the same time, and will suddenly feed out of control. Therefore, we should analyze and eliminate the fault phenomenon.

CNC vertical milling machine, FANUC CNC system, in the processing process, the X-axis, Y-axis and Z-axis suddenly move rapidly at the same time, resulting in the collision of the machine tool and the damage of the tool and the workpiece. The reason why the coordinate axis suddenly loses control is usually caused by the opening of the position loop. When the above problems occur in an axis, it is generally caused by the fault of the position boundary measurement system of the servo system. However, on this machine tool, since all axes of the machine tool have problems at the same time, the fault reason should be related to the common part of the system. Considering that all position encoders of the machine tool are powered by a unified power supply module, if the + 5V of the power supply module is poor, the three-axis position ring of the system will fail at the same time. Carefully measure the power module of the machine tool and compare it with similar machine tools. When the + 5V power supply of the machine tool is unloaded, the voltage is normal. After measurement, connecting the load, it is found that when the output current of the power module is 4A, the output voltage drops to 4.25v; When the output current is 10A (rated output), the output voltage drops to 2V. However, on normal machine tools, when the output current is 10A (rated output), the output voltage still remains 5V, so it is confirmed that this fault is related to the power module. After directly replacing the power module, the machine tool returns to normal.