Common troubleshooting methods for CNC machine tools

Since CNC machine tool failures are relatively complex, and the CNC system's self-diagnosis capability cannot test all components of the system, one alarm number often indicates a multitude of fault causes, making it difficult to troubleshoot. The following introduces the troubleshooting methods commonly used by maintenance personnel in production practice.

1. Visual inspection method

The visual inspection method is that maintenance personnel determine the scope of the fault based on the observation of various abnormal phenomena such as light, sound, and smell when the fault occurs. The fault scope can be narrowed down to a module or a circuit board, and then eliminated.

2. Initialization reset method

Generally, if the system alarm is caused by a transient fault, the fault can be cleared by hardware reset or switching the system power on and off. If the system working storage area is confused due to power failure, plugging and unplugging of circuit boards, or battery undervoltage, the system must be initialized and cleared. Before clearing, you should pay attention to copying and recording the data. If the fault cannot be eliminated after initialization, perform hardware diagnosis.

3. Self-diagnosis method

The CNC system has a strong self-diagnosis function and can monitor the working status of the hardware and software of the CNC system at any time. The self-diagnosis function can display the status of the interface information between the system and the host, so as to judge whether the fault occurs in the mechanical part or the CNC part, and display the general location of the fault (fault code).

4. Functional program testing method

Functional program testing is to program the functions of the CNC system into a functional test program and store it on the corresponding media, such as paper tape and magnetic tape. When running this program during fault diagnosis, the possible cause of the fault can be quickly determined. Functional program testing is often used in the following situations: when machine tool processing causes waste and it is not possible to determine whether it is caused by improper programming or CNC system failure; when the CNC system has random failures and it is difficult to distinguish whether it is external interference or poor system stability; when CNC machine tools that have been idle for a long time are put into use or when regular maintenance is performed on CNC machine tools.

5. Spare parts replacement method

Replace the bad circuit board with a good spare part, that is, after analyzing the general cause of the fault, the maintenance personnel can use the spare printed circuit board, integrated circuit chip or component to replace the suspicious part, thereby narrowing the scope of the fault to the printed circuit board or chip level. And do the corresponding initialization and start up, so that the machine tool can quickly put into normal operation.

For the maintenance of modern CNC, this method is increasingly used for diagnosis, and then the damaged module is replaced with a spare part to make the system work normally and shorten the downtime as much as possible.

Notice:

(1) When using this method, be sure to operate it under power outage, and carefully check whether the version, model, various markings, and jumper of the circuit board are the same. If they are not consistent, they cannot be replaced. When removing the wires, make sure to mark and record them.

(2) Generally, do not replace the CPU board, memory board and battery easily, otherwise it may cause the loss of program and machine tool parameters and expand the fault.

6. Parameter Check Method

System parameters are the basis for determining system functions. Wrong parameter settings may cause system failure or invalid functions. When a failure occurs, the system parameters should be checked in time. The parameters are generally stored in bubble memory or MOSRAM that needs to be maintained by batteries. Once the battery is low or due to external interference, individual parameters are lost or changed, confusion occurs, and the machine tool cannot work normally. At this time, the fault can be eliminated by checking and correcting the parameters.

7. Principle analysis method

According to the composition principle of the CNC system, the logic level and characteristic parameters of each point, such as voltage value and waveform, can be logically analyzed, and instruments can be used to measure, analyze and compare to determine the fault location.

Other troubleshooting methods

In addition to the above commonly used fault detection methods, you can also use the plug-in board method, voltage deviation method, open-loop detection method, etc. In short, according to different fault phenomena, you can use several methods at the same time for flexible application and comprehensive analysis, so as to gradually narrow the scope of the fault and eliminate the fault quickly.

There are many reasons for machine tool failure. For more complex failures, several methods need to be used in combination to correctly determine the cause of the failure and diagnose the specific location of the failure, so as to solve the failure in time, reduce the loss of CNC machine tools to production, and effectively improve the efficiency of machine tools.