Tool wear progression of PCD and PCBN cutting tools in high speed machining of NiTi shape memory alloy under various cutting speeds

NiTi shape memory alloys are coming into prominence in various industrial applications owing to their unique shape memory effect, super-elasticity and mechanical properties. However, this material is characterized by its very poor machinability rates. One of the major reasons of this problem is the high tool wear rate, which primarily occurs due to nature of this material. The previous work reported in the literature has been limited to investigate low to medium speed machining characteristics of this material especially with carbide and coated carbide cutting tools. This paper presents the results of experimental investigation on the progressive wear behaviors of Polycrystalline Diamond (PCD) and Polycrystalline Cubic Boron Nitride (PCBN) cutting tools in turning of equi-atomic NiTi shape memory alloy. Effects of cutting speed, which varied between Vc = 70 and 250 m/min, were investigated. Periodical tool wear measurements were conducted in order to find tool life and evaluate wear mechanisms. The results show that tool wear mechanism is highly cutting speed dependent. PCD cutting tool performed better wear resistance at all of the investigated cutting speeds. The optimized cutting speed and cutting tool couple is suggested to increase productivity regarding longer tool life.