A Model for Maintenance Planning and Process Quality Control Optimization Based on EWMA and CUSUM Control Charts

Abstract

The performance of a production system is highly dependent on the smooth operation of various equipment and processes. Thus, reducing failures of the equipment and processes in a cost-effective manner improves overall performance; this is often achieved by carrying out maintenance and quality control policies. In this study, an integrated optimization method that addresses both maintenance strategies and quality control practices is proposed using an exponentially weighted moving average (EWMA) chart, in which both corrective and preventive maintenance policies are considered. The integrated model has been proposed to find optimal decision variables of both the process quality decision parameters and the optimal interval of preventive maintenance (i.e., Ns, Hs, L, λ, and ) to result in overall optimal expected hourly total system costs. A case study is then utilized to investigate the impact of cost criteria on the proposed integrated model and to compare the proposed model with a model using the cumulative sum (CUSUM) control chart. The improved model outputs indicate that there is a reduction of 34.6% in the total expected costs compared with those of the other model using the CUSUM chart. Finally, an analysis of sensitivity to present the effectiveness of the model parameters and the main variables in the overall costs of the system is provided.

A New Integrated Risk-Assessment Model for Minimizing Human-Machine Error Consequences in a Preventive Maintenance System

“…1) Suppose a multi-component system has critical components that influence the system's reliability, and the system will stop working if those components fail [57]. 2) Preventive maintenance procedures for critical system components are performed without a need for a system to stop working, while corrective maintenance procedures cannot be performed without a system stopping [58]. 3) Maintenance workers often make errors when implementing procedures for checking or maintaining system components due to various factors (e.g., lack of procedures understanding, work pressures, complexity of system components, lack of experience or training, and other factors related to work environment as atmosphere temperature, lighting, noising, etc.…”

“…In this case, the costs for system restoration include spare parts costs, maintenance labor costs, and production loss costs due to system shutdown. The expected corrective maintenance cost (EC CM ) can be calculated as follows [57,58].…”

“…In this case, the system repairing costs include materials required for preventive maintenance actions, labor costs, and production loss costs. The expected preventive maintenance cost (EC PM ) can be calculated as follows [57,58].…”