Cryogenic orthogonal turning of Ti-6Al-4V

Abstract

Cooling of machining operations by liquid nitrogen is a promising approach for reducing cutting temperatures, increasing tool life and improving the workpiece surface integrity. Unfortunately, the cooling fluid tends to evaporate within the supply channel. This induces process variations and hinders the use of nitrogen cooling in commercial applications. In this work, the coolant is applied via the tool’s rake face during orthogonal turning of Ti-6Al-4V. The effect of a nitrogen supply pressure adjustment and a subcooler usage—proposed here for the first time for machining—is analyzed in terms of process forces, tool temperatures and wear patterns, taken dry cutting as a reference. Thereby, reliable cooling strategies are identified for cryogenic cutting.

Recent progress and evolution of coolant usages in conventional machining methods: a comprehensive review

“…However, the machining costs were found to increase as the flow rate increased. Moreover, Stampfer et al [ 65 ] concluded that machining forces and cutting tool temperatures were reduced by using high-pressure cryogenic coolant (nitrogen) supply on orthogonal turning of titanium alloy. Also, the tool wears on internal rake face of the cutting tool were reduced under cryogenic cooling compared to dry cutting.…”

Review of new developments in machining of aerospace materials

“…As a countermeasure insulated pipes, insulated tools or a phase separator are usually used, however their effectiveness is questionable. Attractive alternative is subcooling, a known principle when LN2 is used to cool silicone chips in microelectronics which was recently proposed in the application of cryogenic cutting [21], (Fig. 5).…”

“…5. Setup of the nitrogen supply with subcooler and comparison of standard nitrogen supply (red line) and the subcooler case (blue line) [21] Subcooler usage decreases the nitrogen evaporation rate and accelerates the initial cooling of the supply system. Therefore, increased mass flow rates result at the same working pressures, compared to systems without subcooling.…”