Modeling of hard part machining: Effect of insert edge preparation in CBN cutting tools

High speed machining of hardened steels for manufacturing dies and molds offers various advantages, but the productivity often limited by mainly tool life. This study investigates the influence of edge preparation in cubic boron nitrite (CBN) cutting tools on process parameters and tool performance by utilizing practical finite element (FE) simulations and high speed orthogonal cutting tests. The predicted process parameters through FE simulations in high speed orthogonal cutting are expected to help optimize tool life and surface finish in hard machining of AISI H-13 hot work tool steel. A set of orthogonal cutting experiments using honed and chamfered CBN tools was performed and primary cutting force and thrust force were measured by using a force dynamometer along with a PC-based data acquisition system. The same set of cutting conditions was used in numerical FE simulations to predict forces, stresses and temperatures developed at the honed and chamfered CBN tools. Simulation results provided a distribution of stresses and temperatures at the cutting zone, chip-tool and workpiece-tool interfaces. Numerical simulations include testing different edge preparation geometry for CBN tools at different cutting speeds and feeds. The results show that a zone of workpiece material is formed under the chamfer acting as an effective rake angle during cutting. The presence of a chamfer affects the cutting forces and temperatures while no significant change in chip formation observed.