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Manufacturing companies are increasingly required to deal with and introduce significant changes in their production systems to gain a competitive advantage. The production system design process is widely considered a means of introducing such changes, and decisions made during design are viewed as critical to its characterization and performance. However, this presents a problem because committing to decisions that involve significant changes implies not only dealing with requirements, products, challenges, or expectations that are different from what currently exists, but also addressing uncertainties regarding both the information necessary for committing to a production system design decision and the actual benefits that can be achieved as a result of these changes. One way to support the production system design decisions in this context is through the use of Discrete Event Simulation (DES). However, understanding of DES use when supporting production system design decisions in this domain remains limited.    

Therefore, the objective of this thesis is to explore the use of DES in support of production system design decisions when significant changes are introduced. Data are collected through a multiple case study method and DES from three real-time production system design projects at one manufacturing company. All production system design projects studied involved the introduction of significant production system changes for which limited experience existed. The cases and results are presented in three appended publications.

The findings establish the purpose of DES use when supporting production system design decisions in this context. To this end three groups of DES model objectives are identified: communicating decisions and visualizing results, evaluating a production system design concept focused on operational performance, and experimenting with what-if scenarios while predicting production system outputs. The points of DES use when supporting production system design decisions are specified in relation to current theoretical understanding of a production system design process. Then, challenges and contributions of DES use supporting production system design decisions are identified.

A framework is presented to facilitate the use of DES supporting production system design decisions when significant changes are introduced. The framework is based on the identification of high-level strategic objectives and relates these to production system design decisions. It defines DES use in support of these decisions and establishes milestones for DES use during production system design. Based on an analysis of the challenges and contributions of DES use, the framework helps formulate the purpose of DES use to achieve production system design decision support.