develoPement of tOoLs for cryogenic mAchining pRogressIon to a SuStainable machining – POLARISS

The machining of titanium alloys requires the use of cutting fluids (soluble / whole oils) which has a strong positive impact on productivity, but also very negative on ecology. The REACH regulation presents chemical and biological risks and imposes a strong restriction on these petroleum products to protect the health of operators. For 15 years, strong incentives have been given to manufacturers to make a transition to cleaner processes. The elimination of cutting oils is therefore an important issue. The objective of the POLARISS project is to replace cutting oils with cryogenic fluids (N2 or liquid CO2), which is called cryogenic machining. The results are very positive for many materials, but they depend on the tool used. The tool is therefore an important factor for the development of cryogenic machining, yet there is currently no tool developed specifically for these fluids. The POLARISS project therefore proposes to develop a specific tool for cryogenic machining. Texturing of the cutting face of the inserts will be proposed to improve the cooling of the tip of the tool. Consideration will also be given to modifying the composition of the cutting tool, in order to limit or even eliminate cobalt as a binder which has a strong chemical affinity with titanium and thus promotes wear by adhesion. Significant attention will be paid to the development of hard coatings as protective materials on cutting tools in order to increase their service life. Thus, the effect of new Cr-based PVD multilayers (different architectures) and new thin layers of CVD nitrides or carbonitrides will be studied on carbide tools during cryogenic machining. These innovative and complementary approaches seem very promising for the optimization of tools in cryogenic machining, and thus allow the elimination of cutting oils.