At present, CNC machining is widely used in the mechanical processing industry due to its advantages such as stable production quality, high productivity, and improved working conditions for workers. However, in the process of use, it is inevitable for the operator to encounter various malfunctions. Based on some of the problems that students encounter in teaching activities, the author summarizes the following fault situations and analyzes them one by one to explain the solutions.

1、 The program format is illegal

Some students' CNC machining programs are inputted into the CNC system and run to simulate graphics. During this process, the machine tool alarms. We can find the corresponding content of the alarm information on the alarm status list page: the program format is illegal. If this situation occurs, we need to carefully check each program segment and find statements that do not conform to the instruction format of the CNC system, such as: missing parameters R or I for instructing the center position after arc interpolation in G02/03 format J、K； After arc interpolation, it became line interpolation, but the program forgot to add the G01 instruction. As a result, since the G02/03 instruction is a modal instruction, the latter statement defaults to arc interpolation, resulting in an error.

2、 Incorrect G code

The reason for this phenomenon is that G code that is not supported by the system was entered into the program. When operating a specific machine tool, we must first read the instruction manual provided by the machine tool, understand and master the instruction codes used by the system, and avoid making empirical mistakes. In addition, different CNC systems, even different models and versions of the same CNC system, support different instructions.