Using Fuzzy FMEA Approach to Improve Decision-Making Process in CNC Machine Electrical and Control Equipment Failure Prediction

Reliability and safety in the process industry, such as computer numerical control (CNC) machining industry, are the most important key success factors in upgrading availability and preventing catastrophic failures. Failure Mode and Effects Analysis (FMEA) method is one of the most useful approaches to the maintenance scheduling and, consequently, improvement of the reliability. This paper presents an approach to prioritize and assess the failures of electrical and control components of CNC lathe machine. In this method, the electrical and control components were analyzed independently for every failure mode according to risk priority number (RPN). The results showed that the conventional method by means of a weighted average generated different RPN values for the subsystems subjected to the study. The best result for Fuzzy FMEA was obtained for the 10- scale and centroid defuzzification method. The Fuzzy FMEA sensitivity analysis showed that the subsystem risk level was dependent on occurrence (O), severity (S), and detection (D) indices, respectively. The result of the risk clustering showed that the failure modes could be clustered into three risk groups, and a similar maintenance policy could be adopted for all failure modes placed in a cluster. In addition, the prioritization of risks could also help the maintenance team to choose corrective actions consciously. In conclusion, the Fuzzy FMEA method was found to be suitably adopted in the CNC machining industry. Finally, this method helped increase the level of confidence on CNC lathe machine.