Evaluation is considered as one of several activities necessary to master in the competitive environment that manufacturing companies experience today. The specific situation addressed in this dissertation is evaluation during development of assembly systems. The role of evaluation varies and an enhanced understanding of different evaluation situations is required. Evaluation has not yet become an explicit part of the activities aimed at suitable assembly systems. Despite the large numbers of evaluations carried out in other areas, experiences thereof have not yet been applied in the evaluation of assembly systems. The objective of the research was to explore different evaluation situations in order to elucidate the circumstances under which evaluation can be supportive, and how evaluation can be facilitated, during development of assembly systems. The empirical material was collected during studies of 11 manufacturing companies in Sweden. The research design involved an interview study and three case studies. During the empirical studies, different evaluation situations were explored and circumstances affecting evaluation were sought.

The analysis, which takes its starting point in assembly system development from a decision process perspective, revealed circumstances associated with the different decision processes affecting evaluation. Moreover, three identified system design approaches were found useful for understanding the different evaluation situations. The identified circumstances affecting evaluation were found to be related to the assembly system as such, i.e. the evaluation object, or to the development process, i.e. the activities carried out where the evaluations were  escribed. As a result of the empirical studies and the theoretical considerations, a framework evolved during the research. The Assembly System Evaluation Framework is a heuristic tool, aimed at facilitating understanding of the circumstances under which evaluation is carried out during the development of assembly systems. The framework involves three evaluation situations: evaluation of existing assembly systems, evaluation of different alternatives, and finally evaluation of an implemented system. Supported by the framework, the characteristics of the evaluation situations are elucidated. Different obstacles and enablers affecting the evaluation situations are discussed, and the possibility of facilitating evaluation through the application of different evaluation models and explicit considerations to evaluation is pointed out.