STP1097

    Suspension Systems for Today's Manufacturing Environment

    Published: Jan 1990


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    Abstract

    Manufacturing today is going through a major change; two features of this change are the reduction or elimination of inventory (Just-In-Time) and a new, plant-wide emphasis on quality (Total Quality Control). One particular technique for never-ending improvement of quality is called line-stop, where operators on the production line have the authority to stop production when an indication of quality deterioration is observed.

    Suspension systems are well-suited for the line-stop technique. A suspension system is the combination of a suspension rule, designated (j,k), and a lot by lot inspection plan; suspension occurs if j lots are rejected in k or fewer lots. A simple rule such as stop production if two lots are rejected within five or fewer lots (2,5) can be used, avoiding the use of perhaps subjective impressions by the operator concerning quality.

    This paper reviews the characteristics of such rules, highlighting their mean time to suspension or Average Run Length. Suspension systems are compared to cumulative sum charts. Cumulative sum charts have shorter average run lengths, but not by much; suspension systems are easier to understand and easier to use, requiring no calculations at all in their daily use.

    Keywords:

    acceptance sampling, suspension system, average run length, cumulative sum chart, line-stop


    Author Information:

    Troxell, JR
    Associate Professor of Quantitative Analysis, La Salle University, Philadelphia, PA


    Paper ID: STP25441S

    Committee/Subcommittee: E11.03

    DOI: 10.1520/STP25441S


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