In-process high-speed photography applied to orthogonal turning

Material behaviour understanding is a basic pillar for the building of predictive models applied to machining processes and the majority of the formulated material flow rules that are intimately associated to strain and strain rate. The use of high-speed filming allows observing a sequence of frozen images focused on the chip formation area when machining steel in orthogonal turning tests. This article presents the set-up and images acquired over square grid marked tube work-pieces on 42CrMo4 steel. Variables such as chip geometry, shear angle, strain, strain rate, chip thickness, and tool vibration amplitude are measured. Information acquired by the displacement of flow patterns allows measuring of plastic variables. Strain and strain rate results are calculated and compared to analytical modelling results. Industrial machining speeds and feeds are analysed by means of short shutter times, high image acquisition rates, and high magnifications achieving a good compromise between image quality, recording continuity, and cost of the equipment and experiments.