Using PCR-TOPSIS to optimise Taguchi's multi-response problem

The Taguchi method is an efficient method used in off-line quality control where experimental design is combined with quality loss. This method includes three stages-system design, parameter design, and tolerance design. In the real world it is obvious that more than one quality characteristic should be considered for most industrial products; i.e., in most applications the customer's concern is with multi-response problems. Nevertheless, the Taguchi method is not appropriate for optimising a multi-response problem since engineering judgment is the main optimisation procedure in Taguchi method. In order to overcome this problem, this paper proposes an effective procedure called PCR-TOPSIS that is based on process capability ratio (PCR) theory and on the theory of order preference by similarity to the ideal solution (TOPSIS) to optimise multi-response problems. Using PCR-TOPSIS, multiple responses in each experiment will be transformed into a performance index. Therefore, the optimal factors/levels combinations for the multi-responses can be determined. Two case studies in Tarng et al. and Reddy et al. are resolved using the proposed procedure. The result indicates that PCR-TOPSIS can yield a satisfactory solution for multi-response problems.