Switchgear Component Commonality Design Method Considering Delivery Lead-Time and Inventory Level

Product families are groups of related products that take advantage of part commonalities at various levels to streamline delivery of maximal product variety with minimal cost impact and as short as possible lead-times. This paper proposes a new integrated product design method for build-to-order production system based products, using the product family concept, which considers product performance, delivery lead-time and inventory cost. The development and discussion of this method uses a switchgear design problem as a concrete and practical design case. A build-to-order production system has been applied to switchgear manufacturing due to its small-scale production and a variety of customer requirements. However, if the risk of maintaining unsold inventory can be decreased, manufacturers can justify holding an amount of versatile inventory. In this paper, inventory production system is applied to the switchgear production problem to shorten the delivery lead-time. The switchgear design and production problem is formulated using three objective functions, which are subassembly procurement lead-time, inventory cost and area occupied by various switchgear configurations. Moreover, to assist inventory cost evaluations, a simulation procedure for the inventory system is proposed. The proposed method is used to obtain a Pareto optimal solution set of the three objective functions. Finally, an example switchgear design problem is solved to illustrate that optimal use of component commonalities across different modules can significantly reduce inventory costs, while also shortening product delivery lead-times.