NC machine tool is a very complicated equipment which includes many applied disciplines. In addition, there are many types of NC system and machine tool, and their functions are different, it is difficult to find a general detection method which is suitable for all high-speed precision tool tower tail top machine and all types of problems. Below we will only explain some common general methods, these methods are related to each other, in the actual fault detection, these methods to be integrated.

       1. Although the modern numerical control system has not yet achieved a very high level of intelligence, but it has a strong self-detection function. Can monitor the working condition of hardware and software of CNC system at any time. If something goes wrong, immediately display an alarm message on the CRT or light-emitting diode the approximate cause of the problem. By using the self-detection function, it can also display the state of the interface signal between the system and the host computer, so as to distinguish whether the problem occurs in the mechanical aspect or in the numerical control system aspect. This method is one of the effective methods for maintenance work at present.

       2. Function program test method, the so-called function program test method is the numerical control system common function and the special function, such as linear positioning, arc interpolation, spiral cutting, fixed cycle, user macro-programming methods, such as manual programming or automatic programming, compiled into a functional test program, programmed into the CNC system, the CNC system is then activated to check the accuracy and stability of the machine in performing these functions, thus identifying the possible causes of the problem. In this method, it is difficult to determine whether it is a programming error, an operation error or a machine tool problem when the long-term idle NC machine tool is checked at the first start and the processing of the NC machine tool appears a waste product without alarm, this is a good way to distinguish.

      3. Isolation method, isolation method is to interrupt some control circuits, so as to achieve the effect of narrowing the scope of the problem. Example: a machining center, in the JOG mode, feed stability, but automatic is a problem. First of all, to determine whether it is a NC problem or a servo system problem, first interrupt the servo speed given signal, using the battery voltage as the signal, the problem remains, indicating that there is no problem in the NC system. Further inspection revealed a problem with the Y-axis clamping unit.

      4. Partial heating method, after a long-term use of CNC system components are aging, performance will be reduced. When they are not completely damaged, problems can become sporadic. At this time can be used hot hair dryer or electric iron to some of the suspected components to heat up, accelerate its aging, in order to thoroughly expose the problem parts. Of course, when taking this method, we must pay attention to the temperature parameters of components, do not turn the original is good device baked bad.