It is important to distinguish the type of failure of bus processing machine, which has great reference value for the maintenance of the machine.

(1) According to the probability of failure, it can be divided into systematic failure and random failure. Systematic fault refers to the definite fault which will occur as long as certain conditions are met. The random fault refers to the occasional failure under the same conditions, the analysis of this kind of fault is more difficult, usually with the machine tool mechanical structure of local loose dislocation, part of the electrical workpiece characteristic drift or reliability reduction, electrical device internal temperature is too high. The analysis of this kind of fault can be eliminated only after repeated test and comprehensive judgment.

(2) According to whether there is damage when the fault occurs, it can be divided into destructive faults and non-destructive faults. For destructive failure, damage to the workpiece or even the fault of the machine tool, maintenance is not allowed to repeat, then only according to the phenomenon of the failure of the corresponding inspection, analysis to eliminate it, technical difficulty is high and there is a certain risk. If it is possible to damage the workpiece, remove the workpiece and try to reproduce the failure process, but with great care.

(3) According to the occurrence of faults without indication, it can be divided into faults with diagnostic indication and faults without diagnosis indication. Today's numerical control system is designed with perfect self diagnostic procedures, when the real monitoring software and hardware of the whole system performance, once found will immediately report to the police or fault and brief text displayed on the screen, combining system equipped with diagnostic manual can not only find the cause of the failure and parts, but also eliminate the method. Machine tool manufacturers will also design specific machine tool failure instructions and diagnostic instructions. The above two parts of the diagnostic indication of the fault together with the various types of lights on the electrical device makes the troubleshooting of most electrical faults easier. The failure without diagnostic indication is partly due to the incompleteness of the above two diagnostic procedures (e.g. switch not closed, loose plug, etc.). This kind of failure depends on the working process and fault phenomenon and consequences before the failure, and relies on maintenance personnel to analyze and eliminate the familiarity and technical level of machine tools.

(4) According to the location of the fault, it can be divided into hardware fault and software fault. Hardware fault refers to the abnormal state or even damage of electronics, electrical parts, printed circuit boards, wires and cables, connectors, etc., which need to be repaired or even replaced to eliminate the fault. And software fault is to point to PLC logic control procedure in general the fault that produces, need to input or modify some data even modify PLC procedure can eliminate the fault. Part processing program fault also belongs to software fault. The most serious software failure is the nc system software defect or even loss, which can only be solved by contacting the manufacturer or its service organization.

(5) measured by the motion quality characteristics of CNC machining machine tool, it is the fault that the motion characteristics of machine tool decline. In this case, the machine tool can work normally but not produce qualified workpiece. For example, the positioning accuracy of machine tools is out of tolerance, the reverse dead zone is too large, and the coordinate operation is not stable. This type of fault must be identified by the use of testing instruments to produce errors in the mechanical and electrical links, and then through the mechanical drive system, numerical control system and servo system optimization adjustment to eliminate