Concurrent product and process parameters determination under deterioration process

Abstract

The purpose of this study was to concurrently perform a product and process design for quality and cost consideration. Conventionally, product design and process plan are completed in separate stages. However, there is an opportunity for further cost reduction and quality enhancement if product specification limits are narrowed to make them equal to the process specification limits. Then, this common limit becomes a combined decision variable in the concurrent product and process design. In addition, when the process deteriorates, to create a concurrent process and product design, it is still necessary to consider both process compensation and periodic resetting to alleviate the negative impact caused by process deterioration as much as necessary. Thus, the decision variables will include initial values (process means), process tolerances, combined limits, and the resetting cycle. The measurement score for evaluating these decision variables is the total cost: that is, the sum of mean cost, tolerance cost, quality loss, inspection cost, and failure cost. Because the nature of the above cost items, the model is much appropriate for off-line application, that makes concurrent product and process design become possible before process actualization. An example is presented to demonstrate the proposed approach.