Maintenance and quality control integrated strategy for manufacturing systems

This paper addresses the problem of integration of maintenance and quality control in manufacturing systems which are subject to a degradation process that directly affects the quality of the produced items. Process and product quality control is carried out using an 'x-bar' control chart. According to the average of the measurements of the quality indicator x compared to monitoring and control limits, it is decided to undertake or not a maintenance action that can be either preventive or corrective. A mathematical model is developed to determine the optimal values of the decision variables that are: the sample size, the sampling interval, the number of samples, as well as the monitoring and the control limits of the control chart. The objective is to minimise the average total cost per time unit integrating maintenance and quality costs. A numerical example and a sensitivity analysis are presented to illustrate the proposed approach.