Within the context of high-speed machining, the different steps of the free-form elaboration process are at the origin of errors leading to quality decreasing of the product and lack of productivity. Indeed, due to these errors, trajectory execution involves geometrical deviations on the resulting machined surface. The control of these deviations is the main part of this study. First, research work deals with a detailed analysis of the process: trajectory calculation, interpolation carried out by the numerical controller, dynamical behaviour of the machine tool structure during machining. This analysis leads to the identification of the main sources of errors, and to evaluate corresponding geometrical deviations between the tool and the workpiece all process long. Among the various errors, the execution stage is a major source of the errors. Therefore, a modelling of the feed-drives is proposed with the aim of predicting execution errors. The model proposed is assessed through a series of trials performed with different machine-tools. This model is the support of the process optimisation. The process optimisation is approached with the minimization of geometrical deviations resulting from the effective tool trajectory while preserving productivity. A compensation method based on an inverse model is then proposed: the contouring error compensation method (CEC). This method takes advantage of the feeddrive model to predict deviations generated during the execution step (interpolation and servo). Illustrations highlight the efficiency of the CEC method in the reduction of geometrical errors.
