High-speed five-axis milling of hardened tool steel

This paper investigates critical issues related to high-speed five-axis mil ling of hardened D2 tool steel (hardness HRc 63). A forging die cavity was designed to represent the typical features in dies and molds and to simulat e several effects resulting from complex tool path generation. Cutting tool materials used were coated carbide for the roughing and semi-finishing pro cesses and polycrystalline cubic boron nitride (PCBN) for the finishing pro cess. The effects of complex tool paths on several critical machining issue s such as chip morphology, cutting forces, tool wear mechanisms, tool life and surface integrity were also investigated. The main tool failure mode wa s chipping due to the machine tool dynamics. A five-axis analytical force m odel that includes the cutter location (CL) data file for computing the chi p load has been developed. The effect of instantaneous tilt angle variation on the forces was also included. Verification of the force model has been performed and adopted as a basis for explaining the difficulties involved w ith high-speed five-axis milling of D2 tool steel. (C) 2000 Elsevier Scienc e Ltd. All rights reserved.