Comparison of Ti6Al4V machining forces and tool life for cryogenic versus conventional cooling

The benefits of cryogenic cooling by liquid nitrogen in cutting of titanium alloys have often been evaluated as a comparison to dry machining conditions. However, it is more interesting to quantitatively assess the performance of cryogenic conditioning of the process with respect to standard industrial conditions, that is, with respect to flood emulsion cooling. The technical and scientific literature is scarce and somehow contradictory, especially in terms of cutting forces and coefficient of friction. The aim of this article is to enrich the common base of experimental data, by conducting a comparison of traditional and cryogenic turning of Ti6Al4V in a region of cutting parameters particularly relevant to the aerospace industry, where no previous data are available. This study confirms that cryogenic machining is able to increase the tool life, even with respect to wet cutting. Besides, the results show that not only cutting forces are reduced but also a small, albeit significant, reduction can be achieved in the coefficient of friction at the tool-workpiece interface.