A Comprehensive Evaluation Method for Generalized Reliability of CNC Machine Tools Based on Improved Entropy-Weighted Extensible Matter-Element Method

Computerized numerical control (CNC) machine tools are typically repairable products. Reliability indicators should be combined with maintenance and availability indicators to fully reflect the level of operational reliability of the machine tools. At present, most of the methods for the comprehensive evaluation of the generalized reliability of CNC machine tools are based on a specific indicators system, the model has a strong subjectivity and can not be changed in a timely manner when the indicators change. This paper proposes a generalized reliability evaluation method for CNC machine tools based on improved entropy weight extensible matter-element model. Introducing contrast intensity and conflict intensity to consider the interrelationships between indicators to improve the entropy weighting method. Meanwhile, the grading method of the extensible matter-element model is improved to replace the scoring grading with the adaptive grading of the indicator data. This makes the methodology not only more objective and independent of the type of indicators, but also able to make timely and accurate changes when the indicators change. The method of this paper is applied to a five-axis CNC machine to conduct a generalized comprehensive reliability evaluation and compared with the traditional method. The results show that this method is more integrated and practical.