A Methodology to Support Product Family Redesign Using Genetic Algorithm and Commonality Indices

Abstract

Many of today’s manufacturing companies are using platform-based product development to realize families of products with sufficient variety to meet customers’ demands while keeping costs relatively low. The challenge when designing or redesigning a product family is in resolving the tradeoff between product commonality and distinctiveness. Several methodologies have been proposed to redesign existing product families; however, a problem with most of these methods is that they require a considerable amount of information that is not often readily available, and hence their use has been limited. In this research, we propose a methodology to help designers during product family redesign. This methodology is based on the use of a genetic algorithm and commonality indices - metrics to assess the level of commonality within a product family. Unlike most other research in which the redesign of a product family is the result of many human computations, the proposed methodology reduces human intervention and improves accuracy, repeatability, and robustness of the results. Moreover, it is based on data that is relatively easy to acquire. As an example, a family of computer mice is analyzed using the Product Line Commonality Index. Recommendations are given at the product family level (assessment of the overall design of the product family), and at the component level (which components to redesign and how to redesign them). The methodology provides a systematic methodology for product family redesign.

An Index-based Method to Manage the Tradeoff between Diversity and Commonality during Product Family Design

“…Finally, the unique components, such as the waterproof back casing, does not influence the CMC. By looking at the ratio of the last two columns, the CMC helps designers focus on the components that do not respect the desired diversity and commonality [12,33]. Moreover, the CMC can be used in an appropriate optimization-based approach to provide specific information on how to increase the commonality at the component level.…”

“…In a bottom-up (reactive redesign) approach, a company redesigns and/or consolidates a group of distinct products to standardize components and thus reduce costs. Bottom-up approaches found in the literature include product family redesign at John Deere [30] and Sunbeam [31], a method to redesign a large product set to improve product performance and reduce manufacturing costs [30], the redesign of an existing line of products using consumers' evaluations of possible new design with a marketing research technique (conjoint analysis) [31], the product family reasoning system [32], and an optimization-based redesign approach based on commonality analysis [33]. Additional optimization-based approaches are reviewed in [27].…”

“…-Use the CMC to assess the design of the product family; if several competing designs exist, the CMC helps designers select the best one (see [33,36] for more detail). -Improve the selected design using the CMC and appropriate optimization tools [33,36] to increase commonality (component, material, manufacturing process, assembly) while keeping the desired variety.…”

“…The CDI is now used to ensure that the tradeoff between commonality and diversity is not lost when the design of each product is refined, while the CMC is employed to assess more comprehensively the design and improve it. By integrating information, such as the manufacturing processes, materials, assembly, and component costs, the CMC employed with appropriate optimization tools [33,36] provides recommendations for designers on where and how to increase commonality without losing the desired variety.…”

“…-Improve the selected design using the CMC and appropriate optimization tools [33,36] to increase commonality (component, material, manufacturing process, assembly) while keeping the desired variety. -Use the CDI to ensure that the design possesses the desired commonality and variety at the functional, component, and family levels throughout Stage 2.…”