This paper initiates a framework for improving product development processes. The starting point is the present gap between the theory of product and process models and their actual industrial application in practice. A case study of a multidisciplinary development process that has been processed in a simulation game is presented to concretize the needs for improvement. The case revealed that transparency of the product development process and artefact models is critical in coping with the key problems of conformance, rationale, dynamics, re-use, and milestone integration. Potential means of artefact modeling are discussed for each of the problems in order to propose directions for integrating artefact and process models. Keywords Product models, artefact models, product development, process model, process simulation, integration, transparency.