The economic design of x ‐ control charts under a preventive maintenance policy

Studies the economic design of x ‐ control charts in a situation in which the duration time that the process remains in the in‐control state follows a general distribution which has an increasing hazard rate. In this situation, the active and persistent action for quality control is to design a process in which a preventive maintenance procedure is performed periodically. Addresses first the relationship between preventive maintenance and x ‐ control charts. A cost function which is opposed to those given by Banerjee and Rahim and by Hu is derived. The computational results indicate that the proposed model under a preventive maintenance policy has a lower expected total cost per hour than have those of Banerjee and Rahim’s and Hu’s Weibull shock models. Numerical examples also demonstrate that the model has great flexibility when applied in the situation previously mentioned. Presents the advantages of the combination of a preventive maintenance policy and x ‐ control charts and concludes that a preventive maintenance policy performed under a certain condition can be particularly instrumental in reducing the expected total cost per hour.