Study of the effects of cryogenic machining on the machinability of Ti-6Al-4V titanium alloy

Due to the chemical, mechanical and thermal characteristics inherent to titanium alloys, machining these materials is always considered very difficult. Cryogenic cooling using liquefied gases is one of the techniques used by many researchers to improve the machinability of different materials including titanium by reducing the cutting temperature and modifying the material properties of the workpiece and cutting tool. However despite the introduction of an industrial cryogenic milling system, in the context of machining of titanium, most cryogenic scientific studies are limited to turning operations. This paper is one of the first scientific studies on the cryogenic CNC milling of titanium alloys used in aerospace namely, Ti-6Al-4V (Ti64). A series of machining experiments have been conducted in order to study the effect of cryogenic cooling on the machinability of Ti64 titanium alloy in CNC end milling operations using TiAlN coated solid carbide cutting tools. These experiments showed that cryogenic cooling has resulted in 11% and 59% reduction in the surface roughness of the machined parts as compared to dry and wet conditions respectively whilst no major impact on the power consumption as a result of cryogenic cooling was recorded. In addition, the study of the cutting tools indicated that cryogenic cooling has significant potential to slow down the growth of tool wear resulting in longer tool life in comparison with conventional machining environments.