Assembly process sheets are formal documents used extensively within automotive original equipment manufacturers (OEMs) to document and communicate assembly procedure, required tooling, contingency plans, and time study results. These sheets are authored throughout the vehicle life-cycle. Further, various customers use these sheets for training, analyzing the process, and line-balancing. In this research, the primary focus is the time studies analysis that is completed using knowledge contained within the assembly process sheets. In this research, a method and software tool are developed to utilize coupling between part descriptions and process descriptions for assembly time studies. The method is realized through the development of a standardized vocabulary for describing work instructions, a mapping from work instructions to MTM codes, and a tool for extracting relevant part information from CAD models. The approach enables process planners to establish part-process coupling, author work instructions using the controlled vocabulary, to estimate assembly time. A prototype system is developed and tested using examples from an automotive OEM.