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In this study, a TiN/HfN-coated tool (THN-HF(L)) was developed to improve the processing efficiency of machining austenitic stainless steel. Using scratch tests, this tool was compared with other film-coated tools, and its critical load showed the highest value. The THN-HF(L) tool, whose film was formed in the low bias voltage condition, has a longer tool life than conventional tools. In high-speed cutting (4 or 5 m/s), its tool life is over 20 km. Even though the THN-HF(L) tool's cutting distance surpasses that of conventional tools, adhesion is controlled, and flaking of the film coating on the cutting edge is not observed.

Minimal Quantity Lubrication (MQL) cutting is a successful example of near-dry machining operations. Using actual milling operations, this study shows that equivalent or sometimes superior cutting performance of MQL cutting with a biodegradable synthetic ester lubricant can be achieved in comparison with the conventional cutting with flood coolant supply. There is little investigation on reasons for the preferable performance, such as increase in tool life and the improvement in surface finish. With an extremely low quantity of a lubricant, this study also aims at understanding fundamentally the tribological behavior of a small amount of lubricants during metal cutting. For this purpose, a controlled atmosphere cutting apparatus is developed. The apparatus can introduce a small amount of lubricants in vapor phase into the cutting chamber and can measure their adsorption characteristics by a mass spectrometer. Based on the results obtained by this apparatus, the tribological behavior of a model ester is discussed in connection with the effectiveness of the synthetic ester, which is a suitable lubricant for MQL cutting. Furthermore, the modified version of the apparatus equipped with a cutting force dynamometer is proposed to evaluate the cutting performance in a controlled atmosphere.

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