Economic optimal model integrating statistical process control and preventive maintenance

Under the assumption that the process shift and equipment failure are two different but dependent stochastic processes, and the failure rate increases when the process is out of control, an economic optimal approach by integrating statistical process control and preventive maintenance is proposed. First, five scenarios are defined. By the cost structure analysis and the reliability theory, the cycle cost, cycle time and occurrence probability are then calculated and the integrated model to minimize the expected cost within unit time is set up based on the renewal reward process. A genetic algorithm is designed to solve this model. Finally, several comparative experiments are designed. The results show that this method is superior to other method such as the integrated corrective and plan maintenance model with respect to the cost saving. And other important conclusions are also drawn.