CNC Machine Tools’ Maintenance Decision And Evaluation For Reliability

CNC machine tools have been the mother machine of the modern equipmentmanufacturing industry. They are widely used because they possess the machiningprecision, the stability of the high productivity and good flexibility. In recent years，although the performance of domestic CNC machine tools has certain promotion，butthe difference in level of reliability and maintainability level seriously restricted thedevelopment of China’s CNC machine tool industry. It’s very important to reduce therepair cost, reduce machine down time and improve the competitiveness of the domesticmachine tool, this is very significance to realizing the maintainability level of machinetool. Therefore，this paper from the view of enhancing the reliability level of CNCmachine tools. Established the machine tool maintainability evaluation index system,analysis the factors affecting the maintainability level of CNC machine toolscomprehensively and finally put forward the maintainability level security technologyfor maintainability problems of machine tool, to fully improve the maintainability levelof CNC machine tools presents new methods and ideas. The main contents of this paperinclude the following aspects:First of all, the paper analysis the factors that influenced the CNC machine tools’maintenance level. Starting from the basic theory of maintainability, find out the basicfactors affecting the maintenance level of machine tool. On this basis, considering thecomplexity of CNC machine repair problem and not comprehensive analysis, acomprehensive analysis of the machine tool from design, security, service, repair,personnel five aspect. Factors affecting the machine maintenance is not only the basisfor evaluating the maintainability level below, but also can be used as the criteria ofmachine tool’s repair decision. And then introduces the design technology of CNCmachine maintenance, mainly by simplifying the machine structure, improving thestandardization level of the parts and improving inherent repair accessibility toenhance maintainability level of machine tool.Secondly, put forward the technology of CNC machine tool maintenance decisionbased on RCM and prevention maintenance of the key function component. In terms ofmaintenance decision, established the decision-making mechanism of CNC machinetool based on reliability, insure the machine to take reasonable and effective way repair.During the prevention maintenance stage, establish the machine’s key components optimal preventive interval time model, at the same time, through the seconddevelopment of Siemens CNC system, combined the maintenance time and CNCsystem, avoid overload using, enhances the reliability of CNC machine tools.Finally, establish the evaluation system of CNC machine tools maintenance level.Introduces the basic principle to be followed in evaluation system and methods,establish the index system of CNC machine tools’ maintainability level, introduces theobjective weight coefficient calculation based on entropy weight method and subjectiveweight coefficient calculation based on improved AHP method. Unify the combinedweight model and grey theory, the paper put forward the machine tools’ maintainabilitylevel evaluate system based on grey relational analysis model. This method provides anew method for the evaluation of maintainability level of CNC machine tools.