Applying an improved failure mode effect analysis method to evaluate the safety of a three-in-one machine tool

Straighteners are commonly used in the field of plate straightening. With the shortage of industrial land, an increasing number of straightener manufacturers integrate uncoilers, straighteners, and feeders, which represent a three-in-one machine tool. The tool's functions are complex; many factors affect its reliability and performance, including the problems of equipment itself and human errors. To improve the reliability of this machine, it is necessary to identify the main failure modes and causes. The risk assessment of using the conventional failure mode and effects analysis (FMEA) presents several issues. Thus, multiple methods have been proposed to improve the robustness and applicability of the FMEA. Herein, an improved FMEA, which combines fuzzy set and entropy evaluations is utilized to assess the three- in- one machine tool. In the method, the fuzzy set method is used to quantify the evaluation index. The information entropy and expert evaluation method are used to determine the weight between the indexes. From this study, human operation errors accounted for over 55% of the risks of machine malfunctions. By evaluating failure modes, a few countermeasures to reduce human operation errors can be proposed. By improving the human machine interface design and ergonomic job design and providing adequate training, human errors can be reduced and the reliability of three-in-one machine tools can be improved.