Process Performance Evaluation with Imprecise Information

    Volume 38, Issue 2 (March 2010)

    ISSN: 0090-3973

    CODEN: JTEOAD

    Published Online: 8 December 2009

    Page Count: 6


    Wu, Chien-Wei
    Dept. of Industrial Engineering and Systems Management, Feng Chia Univ., Seatwen, Taichung,

    Liao, Mou-Yuan
    Dept. of Finance, Yuanpei Univ., HsinChu,

    Shu, Ming-Hung
    Dept. of Industrial Engineering and Management, National Kaohsiung Univ. of Applied Science, Kaohsiung,

    (Received 24 April 2009; accepted 24 October 2009)

    Abstract

    Process capability indexes have been widely used in the manufacturing industry for measuring process performance. Most studies on assessing the process capability are based on crisp estimates of process capability indexes while assuming output measurements of the process being precise number. However, in practical situations it is much more realistic that the output characteristics of continuous quantities are more or less imprecise in general. The fuzziness and stochastic uncertainty are unavoidable features of collected observations from continuous quantities. To assess the process performance more accurately, we consider the capability index CPMK, which is recognized as the most useful index to date for assessing the process capability with two-sided specification limits. We construct the fuzzy estimator for the index CPMK according to the fuzzy set theory. To make reliable decisions, we propose a decision rule to assess the process capability based on the fuzzy lower confidence bound of CPMK. A step-by-step procedure for testing process capability is provided for easy execution in practical situations. An example of manufacturing silicon wafers is also presented to illustrate the applicability of the proposed approach.


    Paper ID: JTE102480

    DOI: 10.1520/JTE102480

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    Author
    Title Process Performance Evaluation with Imprecise Information
    Symposium , 0000-00-00
    Committee E11