A contribution to the understanding of chip formation mechanism in high-speed cutting of hardened steel

High-speed machining processes are characterized by their high productivity, good surface finish quality and higher dimensional tolerances. Additionally, these technologies make it possible to execute final machining operations without consequent grinding or similar finishing operations. The newest investigations in the segment of high-speed machining are focused on four characteristic directions: mechanisms of tool wear, quality of surface finish, mechanisms of chip formation, and problems of machining of materials in their hardened state (hard machining). The chip-formation mechanism analysis is an effective tool for deeper understanding of cutting process. During conventional and high-speed milling of the hardened tool steel (X63CrMoV51), with cutting speed range from 50 to 1500 m/min, different mechanisms of chip-formation appear. The analysis covered the chip segmentation frequency, chip shape and dimensions, and also the size of deformed and un-deformed parts of chip segments. The results show that there exists a close relationship among these chip parameters, especially in the region of high-speed machining.