A Design Method of Product Family for Unpredictable Customer Requirements Using Fuzzy Sets

A modular structure recommendation method and component reducing method are proposed for the product family design. The customer’s requirements and the product attributes are represented as a fuzzy set and a fuzzy variable using both a point-based and a range-based approach. On the basis of the fuzzy-based representation of the product and the customer requirements, candidates for the product family are calculated using a combination of components by taking range into consideration. An evaluation method is also proposed for clustering the solutions in the product family. A prototype system for a hand drill provides an example of the development and application of the design. The design results indicate that the proposed method can reduce the number of components from 23 to 14 and that it can lower production cost by 15%. On the basis of the clustering of the candidates generated in the product family plan, a modular structure is found to have common characteristics in highly-evaluated plans. The designer can achieve a modular structure as part of a highly-balanced module that can satisfy customer requirements and have a low cost. The design example concludes that the proposed method effectively finds a good modular structure in the product family.