| Abstract |
This paper proposes an optimal policy which integrates production, inspection, maintenance, minimal repair and inventory problem to consider imperfect rework and inspection errors are allowed for an imperfect production process. We find the optimal inspection interval, the expected number of inspection and economic production quantity of the maximum expected profit per unit. The production process may turn into ¡§out-of-control¡¨ state from ¡§in-control¡¨ state because of the human behavior or the machines. If the production process is ¡§in-control¡¨ state, we execute preventive maintenance, system age is related to the level of preventive maintenance. When the production process is ¡§out-of-control¡¨ state, we assume there are two states: first is slight production process deviation, the production process can be fixed by minimal repair and back to ¡§in-control¡¨ state. It will not change any hazard rate and only become ¡§in-control¡¨ state from ¡§out-of-control¡¨ state. The second one is serious production process deviation, the production process can not be fixed by minimal repair to ¡§in-control¡¨ state. It must stop all the action and begin to repair or replacement. When the production process is ¡§out-of-control¡¨ state, some defective items are produced. Assuming some of the defective items can be reworked and turn to well item, others can not be reworked and turn to waste item. In conclusion, we investigate the benefit of the preventive maintenance in the deteriorated system of the production process. Numerical examples illustrate the effect of preventive maintenance level, imperfect rework, minimal repair and inspection errors on the expected profit per unit. |
