Undercut error and compensating trajectory simulation versus experiments comparison when contour turning of Inconel 718 thin-walled parts

When machining thin-walled parts, one of the main sources of deformation is bending under the effect of cutting forces. This phenomenon generates an undercut defect that can lead to alterations in the dimensions of the finished part. In practice, this problem requires a long and costly iterative trial-and-error loop to be corrected. The solution is not always obvious, as it may involve either modifying the machining parameters, the tool path or the machining fixture. To anticipate these difficulties and help in the decision-making process when developing machining sequences, the use of simulation is of interest. Initially, the aim of this study is to compare the geometric defect measured during machining trials and predicted by simulation. The tests were carried out by turning thin Inconel 718 parts, the geometry of which is a representative portion of a turbine disc. In simulation, a model representing the part’s flexibity is coupled to a model that aims to predict the cutting forces applied. Secondly, a strategy is proposed for defining a compensating trajectory by simulation, with the aim of minimising the geometric defect. The geometric defect is measured after a test using this compensating trajectory. The results show a promising correlation between simulation and experimental testing, and point the way to improvements that will lead to a broader scope of validity.