Machining operations are essential in the production of injection moulds and, accordingly, emerges as a focal point for innovation. In the context of the growing needs for efficiency and sustainability, it is important to develop multifunctional cutting tools. The idea is performing various machining operations, some of them simultaneously, with a single cutting tool, supported on a comprehensive study of operational parameters, lifespan and compliance with specifications. The numerical simulation of machining operations has emerged as a valuable approach for understanding cutting conditions, as it allows the analysis of global parameters, such as cutting forces and torques, and local parameters, such as chip formation and stress distribution. The main objective of using numerical simulation is to minimize the time and cost of experimental tests, since the models allow sensitivity analyses to be performed on different process parameters, including the ones related with the cutting tool geometry. Nevertheless, the numerical simulation of machining processes also poses some challenges, mainly related with the definition of the material mechanical behaviour, process and numerical parameters, to assure a computational cost reasonable for performing sensitivity analysis. The need to extract cutting tool geometry using reverse engineering techniques, combined with the presence of very fine geometric features, introduces additional modelling challenges. This work presents a numerical model of a machining process, highlighting the interconnection with the data extracted from experimental tests, in order to enable a better understanding of the challenges arising in the tool’s geometric description, and in the relation between process parameters and mesh and time discretization.