Integrated planning of production, maintenance and quality

This project integrates production, maintenance, and quality for an imperfect process in a multi-period multi-product capacitated lot-sizing context. Variable costs and prices in the periods and considering the time of maintenance tasks afford flexibility of the model to take into account several scenarios in the system. The machine condition deteriorates with time and it may randomly switch from the initial in-control state to the degraded out-of-control state with increased non-conformity rate. Also, the machine is prone to random failures initiating a corrective maintenance. During each period, in several equidistant intervals the process is inspected and imperfect preventive maintenance activities are simultaneously performed. Improvement in the machine condition is proportional to the preventive maintenance level. The mathematical formulations will use the concepts of reliability, production and quality to evaluate expected values of costs. The objective is either to minimize the total cost or to maximize the profit. Sensitivity analysis will be conducted with respect to the key parameters of the model. Numerical results will quantify the potential improvements that can be achieved from the proposed model. Effect of the model data on cost and profitability will be also discussed. Efficient solution algorithms will be developed and compared, when solving large scale problems inspired by the industrial practice.