The effect of application of cutting fluid with solid lubricant in suspension during cutting of Ti-6Al-4V alloy

The process of machining of hard materials such as titanium and its alloys, has an important role in the development of new machining techniques, such as cutting tools and coatings, with the aim to increase the machinability of these materials. Due to the poor thermal properties of the titanium, the cutting tool suffers accelerated wear which affects the tool life. This paper describes a study of the use of solid lubricant during the machining of Ti-6A1-4V in a turning operation. TiAlN (PVD) coated cemented carbide tool (class S15) was used. Dry tests, tests with lubricant and tests with lubricant with 20% by weight of solid lubricants: graphite mesh 325 (average particle size of 40 mu m), graphite mesh 625 (20 mu m) and molybdenum disulphide (MoS2, 6 mu m) were made. The output parameters are: tool life, surface roughness, cutting force and interfacial temperature (tool-work thermocouple). Tool flank wear, a major problem in machining of titanium alloys, was significantly reduced due to the action of the solid lubricants. Experimental results showed the superiority of molybdenum disulphide in relation to graphite in the turning process: reducing the tool wear, prolonging the tool life and improving the surface roughness. The solid lubricant may be a viable alternative to dry and wet turning. Thus, it may be inferred that proper application of solid lubricants in machining of Ti-6A1-4V alloy results in reduction in tool wear, which can lead to enhancement of productivity. (C) 2015 Elsevier B.V. All rights reserved.