Simulation of industrial cutting processes employing physics based numerical models provide valuable insights into its deformation mechanics. Evaluating such models through chip studies require characterizing complex geometric features like chip shape, and chip curl. In this study, a characterization methodology is developed employing tools like computed tomography (CT) and high speed imaging. The methodology is used to characterize chip curl parameters such as chipside flow angle, chip up curl and chip side curl in oblique nose turning process. To evaluate the methodology, AISI 1045 steel is machined over a range of machining parameters and the chips obtained are characterized. The study shows that the employed methodology can be used to characterize varying chip curl geometries in nose turning process. CT technique is additionally employed when the chips are significantly deformed. The study also shows that the developed characterization methodology could be used to evaluate physics based numerical models.

With advances in modeling of machining process, a methodology for quantitative evaluation of the chip curl shape in orthogonal turning process is highly desired. To achieve this, a function to fit the varying chip curl was required. A mathematical function which is used to describe spiral galaxies is employed in this work which is able to accurately model wide variety of chip curl shapes. The function is employed to compare the chip curl predicted by numerical models with experimental investigations and it should be able to capture the variation of chip curl for varying cutting conditions ranging from tightly wound springs to comma shapes and the transition between them. This provides insights into the evaluation of cutting models from a practical view point. Finite element simulations were performed to predict the chip shape for varying tool rake angles and feed rates in orthogonal cutting process. The results show that the mathematical function was capable to model the wide variety of chip curl shapes encountered in orthogonal turning process.The chip curl predicted by the simulations show that numerical simulations need advanced models to depict work piece material behaviour, heat transfer behaviour and friction behaviour to predict the variation in chip curl shapes accurately for an orthogonal turning process.

Abstract The simulation of machining process has been an area of active research for over two decades. To fully incorporate finite element (FE) simulations as a state of art tool design aid, there is a need for higher accuracy methodology. An area of improvement is the prediction of chip shape in FE simulations. Characterization of chip shape is therefore a necessity to validate the FE simulations with experimental investigations. The aim of this paper is to present an investigation where computed tomography (CT) is used for the characterization of the chip shape obtained from 2D orthogonal turning experiments. In this work, the CT method has been used for obtaining the full 3D representation of a machined chip. The CT method is highly advantageous for the complex curled chip shapes besides its ability to capture microscopic features on the chip like lamellae structure and surface roughness. This new methodology aids in the validation of several key parameters representing chip shape. The chip morphology’s 3D representation is obtained with the necessary accuracy which provides the ability to use chip curl as a practical validation tool for FE simulation of chip formation in practical machining operations. The study clearly states the ability of the new CT methodology to be used as a tool for the characterization of chip morphology in chip formation studies and industrial applications.