Economic-Statistical Design of Integrated Model of VSI Control Chart and Maintenance Incorporating Multiple Dependent State Sampling

The mutualistic relationship between quality control and maintenance of production systems has contributed to the development of the integration model of statistical process control (SPC) and maintenance. Such models are not only beneficial to the improvement of production quality, but also to the reduction of maintenance cost. This paper presents an integrated model of SPC and maintenance that applies a VSI & MDSS X̃ control chart designing based on the variable sampling interval (VSI) scheme and multiple dependent/deferred state sampling (MDSS) policy. A Markov chain approach is employed to model the integrated process, and the average total cost per unit time is derivated and solved by a developed genetic algorithm subject to statistical quality constraints. A shrimp canning production process example is given to illustrate the application of integrated model. Finally, a comparative study using the design of experiments approach is conducted to demonstrate the effectiveness of the suggested model.