The ability to innovate and launch customized products that are well matched to customer demands is a competitive factor for many manufacturing companies. Development of highly customized products requires following an engineer-to-order business process to allow the products to be modified or adapted to new customers’ specifications, which brings more value to the customer and profit to the company.

Design of a new product variant involves a large amount of repetitive and time consuming tasks but also information handling activities that are sometimes beyond human capabilities. Such work that does not rely so much on creativity can be carried out more efficiently by applying design automation systems. Design automation stands out as an effective means of cutting costs and lead time for a range of well-defined design activities and is mainly considered as a computer-based tool that processes and manipulates the design information.

Adaptation and variant design usually concern generating a new variant of a basic design, which has been developed and proved previously, according to new customer’s demands. In order to efficiently generate a new variant, a deep understanding of the previous design is essential. Such understanding can be achieved by access to the design rationale explaining the reasons and justifications behind the design.

Maintenance of design automation systems is essential to retain their usefulness over time and adapt them to new circumstances. New circumstances are, for example, introduction of new variants of existing products, changes in design rules in order to meet new standards or legislations, or changes in technology. To maintain a design automation system, updating the design knowledge (e.g. design rules) is required. Use of design rationale will normally become a necessity to allow a better understanding of the knowledge. Consequently, there is a need of principles and methods to enable capture, structure, and access design rationale.

In this study, a framework for modeling design knowledge and managing design rationale in order to support maintenance of design automation systems is presented. Managing of design rationale concerns enabling capture, structure, and access to design rationale. In order to evaluate the applicability of the framework, the findings are tested through design automation systems in two case companies.