An Optimum Lifecycle Design Method for Long Term Usage Machine Products

Abstract

This paper proposes an optimum system design method that especially considers product lifecycles, and aims to help designers make effective decisions during the product design phase. By considering and estimating all lifecycle factors of cost and environmental impact in addition to the performance of the product, this method facilitates development of optimum design solutions that incorporate requirements pertaining to the product's entire lifecycle. Furthermore, quantitative estimation of lifecycle factors enables the numerical expression of optimum solutions, rather than depending primarily on experiment and designer intuition. To demonstrate the effectiveness of the proposed method, this paper develops an optimum system design method considering product lifecycles for a milling machine as an example of a machine product designed for long term use. The lifecycle cost and the lifecycle environmental impact are generally expressed as the summation of each value during manufacturing phase, usage phase, disposal phase, and recycling phase. In this example model, Eco-indicator 99 is used to evaluate environmental impact. In the proposed lifecycle design optimization method, the relationships among the product performance, the lifecycle cost, which includes the manufacturing cost, and the lifecycle environmental impact are evaluated as a multiobjective optimization problem. Obtaining a Pareto optimum solution set and analyzing it help designers to get clues for breakthrough of the product design.