Abstract
High-speed machining offers several advantages such as increased flexibility and productivity for discrete-part manufacturing. However, excessive heat generation and resulting high temperatures on the tool and workpiece surfaces in high-speed machining leads to a shorter tool life and poor part quality, especially if the tool edge geometry and cutting conditions were not selected properly. In this study, analytical and thermal modeling of high-speed machining with chamfered tools in the presence of dead metal zone has been presented to investigate the effects of cutting conditions, heat generation, and resultant temperature distributions at the tool and in the workpiece. An analytical slip-line field model is utilized to investigate the process mechanics and friction at the tool-chip and tool-workpiece interfaces in the presence of the dead metal zone in machining with a negative rake chamfered polycrystalline cubic boron nitride tool. In order to identify friction conditions, a set of orthogonal cutting tests is performed on AISI 4340 steel and chip geometries and cutting forces are measured. Thermal modeling of machining with chamfered tools based on moving band heat source theory, which utilizes the identified friction conditions and stress distributions on the tool-chip and tool-workpiece interfaces, is also formulated and temperature distributions at the tool, cutting zone, and in the workpiece are obtained. These temperature distributions are compared with the results obtained from finite element simulations. The comparison of temperature fields indicates that the proposed model provides reasonable solutions to understand the mechanics of machining with chamfered tools. Models presented here can be further utilized to optimize the tool geometry and cutting conditions for increasing benefits that high-speed machining offers.
