Burr formation is a significant problem during manufacturing and leads to a lack of geometrical quality through the appearance of undesired and undefined shapes on the workpiece. Thus, understanding the burr formation and elaborating of predictive models are helpful for process design in order to avoid or to reduce burrs and to optimize the strategies for eventual deburring. This study presents both an experimental approach and a model for the plane milling of openwork parts, where burrs are a significant factor. A large-scale analysis of relevant geometrical parameters and their interactions are performed. A phenomenological burr size model is established considering local parameters and the specificities of 3D cutting in milling. Based on local parameters, this article proposes a new methodology to simulate burr height along any part edge and for most face-milling trajectories. Simulations and validations during tool path exits, with changing local parameters, are presented. In addition to the quantitative approach, new 3D aspects of face milling in relation with exit order sequence (EOS) are developed.