A cutting forces model for milling Inconel 718 alloy based on a material constitutive law

This article presents a cutting force model for the milling of Inconel 718 whose machinability is considered to be very poor. The Johnson–Cook constitutive material model is used to determine the flow stress of Inconel 718 while the shear angle is determined based on a shear plane model assuming that the total energy on the shear plane plus the energy on the rake face is minimum. The temperature in the machining region is determined by using an iterative process. Finally, the cutting forces on each tooth of the milling cutter are calculated from its chip load considering the oblique cutting effects. The model is then verified by comparing the model predictions with the experimental data under the corresponding conditions, which shows a relatively good agreement with an average percentage error of 10.5% along the feed and normal directions.No Full Tex

Analytical modelling of cutting forces in near-orthogonal cutting of titanium alloy Ti6Al4V

Titanium and its alloys are difficult to machine due to their high chemical reactivity with tool materials and low thermal conductivity. Chip segmentation caused by the thermoplastic instability is always observed in titanium machining processes, which leads to varied cutting forces and chip thickness, etc. This paper presents an analytical modelling approach for cutting forces in near-orthogonal cutting of titanium alloy Ti6Al4V. The catastrophic shear instability in the primary shear plane is assumed as a semi-static process. An analytical approach is used to evaluate chip thicknesses and forces in the near-orthogonal cutting process. The shear flow stress of the material is modelled by using the Johnson-Cook constitutive material law where the strain hardening, strain rate sensitivity and thermal softening behaviours are coupled. The thermal equations with non-uniform heat partitions along the tool-chip interface are solved by a finite difference method. The model prediction is verified with experimental data, where a good agreement in terms of the average cutting forces and chip thickness is shown. A comparison of the predicted temperatures with published data obtained by using the finite element method is also presented.Full Tex

Slip-line field modelling of rounded-edge cutting tool for orthogonal machining

A new slip-line field model and its associated hodograph of rounded-edge cutting tool were developed for orthogonal micro-cutting operation using matrix technique. The new model considers the existence of dead metal zone in front of the rounded-edge cutting tool. The ploughing forces, chip up-curl radii, chip thicknesses, primary shear zone thicknesses and lengths of bottom side of the dead metal zone are obtained by solving the model depending on the experimental resultant force data. The effects of cutting edge radius, uncut chip thickness, cutting speed and rake angle on these outputs are specified