Fuzzy Evaluation Model of Process Improvement Capability with Costs Consideration

Abstract

The Taguchi capability index, which reflects the expected loss and the yield of a process, is a useful index for evaluating the quality of a process. Several scholars have proposed a process improvement capability index based on the expected value of the Taguchi loss function as well as the corresponding cost of process improvement. There have been a number of studies using the Taguchi capability index to develop suppliers’ process quality evaluation models, whereas models for evaluating suppliers’ process improvement potential have been relatively lacking. Thus, this study applies the process improvement capability index to develop an evaluation model of the supplier’s process improvement capability, which can be provided to the industry for application. Besides, owing to the current need to respond quickly, coupled with cost considerations and the limits of technical capabilities, the sample size for sampling testing is usually not large. Consequently, the evaluation model of the process improvement capability developed in this study adopts a fuzzy testing method based on the confidence interval. This method reduces the risk of misjudgment due to sampling errors and improves the testing accuracy because it can incorporate experts and their accumulated experiences.

Process Quality Evaluation Model with Taguchi Cost Loss Index

“…Many studies have pointed out that Process Capability Indices (PCIs) are not only good communication tools between sales departments and customers but also convenient tools for internal engineers to evaluate and analyze the process capabilities of products [1][2][3][4][5][6][7][8][9][10]. In fact, Process Capability Indices have been widely used in the machine tool industry, semiconductor manufacturing process, and IC packaging industry, electronics industry [11][12][13][14].…”