Determination of flow stress for metal cutting simulation—a progress report

Flow stress data at high deformation rates, necessary for FEA simulation of machining operations, are usually determined with the Hopkinson’s bar high-speed compression tests. In the present study orthogonal slot milling is used in conjunction with quick-stop tests. A computer program, called OXCUT developed at the ERC/NSM, was used to obtain flow stress data from measured forces and primary and secondary shear zone dimensions. Several materials, including AISI 1045, P20 and H13 were tested. The flow stress data obtained with the slot milling method were used to predict forces and temperatures using FEM. The predicted cutting forces were within 20% of experimental values. However, the predicted thrust forces were considerably lower, by about 40%, than the experimental values. Work is in progress to reduce these inaccuracies by improving the estimation of the coefficient of friction and the flow stress value at lower temperatures.