Joint production-maintenance planning in an imperfect system with quality degradation

In this paper, lot sizing problem is integrated with preventive maintenance scheduling taking into account several aspects of the quality system. Integration of such highly dependent decisions in the same mathematical model results in an efficient decision structure, and it can reduce the costs. The significance of the savings resulted from joint models supports the competency of the organization. Age based imperfect maintenance with increasing hazard rate and its influences on production and quality systems is addressed, and related cost evaluations are developed. Length of quality inspection intervals is determined such that the integrated hazard rates over all segments of a period for a certain machine are equal. The optimum value of the integrated hazard depends on multiple factors, including reworking cost, backorder cost, production size, etc. The mathematical model is a nonlinear optimization problem and a genetic algorithm is used to solve it. A numerical example and extensive investigations are also conducted.