Optimum process parameters with imperfect infinite reworks

In this paper, a modified economic manufacturing quantity model under the imperfect product quality is developed. Taguchi's quadratic quality loss function is integrated into the model to evaluate the product quality. The rework process is also imperfect; the reworked item can be one of the qualities: conforming, not usable and scraped, or needing rework again. The three-state Markovian infinite rework of imperfect products is developed and considered in the modified model. By solving the modified model, we can obtain the optimum combination of the production quantity, process mean, and the specification limits that lead to the maximized profit. A numerical example and sensitivity analysis of parameters of the model are provided for illustration.