Investigation of AlCrN-Coated Inserts on Cryogenic Turning of Ti-6Al-4V Alloy

Abstract

Over the past decade, the focus of the metal cutting industry has been on the improvement of tool life for achieving higher productivity and better finish. Researchers are attempting to reduce tool failure in several ways such as modified coating characteristics of a cutting tool, conventional coolant, cryogenic coolant, and cryogenic treated insert. In this study, a single layer coating was made on cutting carbide inserts with newly determined thickness. Coating thickness, presence of coating materials, and coated insert hardness were observed. This investigation also dealt with the effect of machining parameters on the cutting force, surface finish, and tool wear when turning Ti-6Al-4V alloy without coating and Physical Vapor Deposition (PVD)-AlCrN coated carbide cutting inserts under cryogenic conditions. The experimental results showed that AlCrN-based coated tools with cryogenic conditions developed reduced tool wear and surface roughness on the machined surface, and cutting force reductions were observed when a comparison was made with the uncoated carbide insert. The best optimal parameters of a cutting speed (V c ) of 215 m/min, feed rate (f) of 0.102 mm/rev, and depth of cut (doc) of 0.5 mm are recommended for turning titanium alloy using the multi-response TOPSIS technique. on the workpiece materials and cutting conditions [2]. Various coated cutting tools (e.g., TiN, TiAlN, AlTiN, CrN) are available on the market, but machining of Ti alloy still sees problems like the formation of built-up edges on the tools, a rise in wear marks on the cutting edges, and poor quality of machined surfaces. Hence, it is vital to assess the machinability characteristics of Ti alloys in the turning operation using appropriate coatings on cutting tools and advanced techniques of cryogenic lubrication.Chauhan and Rawal [3] reported on nitride ion-based coatings, such as TiAlN, TiMoN, and TiVN, with different deposition techniques. They implied ternary nitride-based coatings showing a higher improvement in tribological and mechanical properties compared to the binary nitride coatings. Bouzakis et al. [4] discussed the evolution of cutting tool coating elements, related coating deposition techniques, manufacturing methods, recent characterization methods, film dimensional thickness, and recondition of wear on coated cutting tools. Their paper shows that as productivity increases, so does the need for improvement. Biksa et al. [5] analyzed the self-adaptive functional coating on cutting tools while machining nickel and titanium-based alloys. It showed the attainment of a better life for AlTiN/MoN-coated tools when machining Inconel 781 and AlTiN/VN-coated tools for Ti-Al6-V4 alloy. This coating was seen as having a smaller coefficient of friction at specific elevated temperatures. Nordegren et al. [6] investigated the plastic deformation modeling on layered carbide tool edges when machining AISI 4340 steel. The result indicated a determined finite element model for the edge thermal effect of the machining process.Ghani et al....