Effects of lubricant on cutting performance in single-point diamond turning of ferrous metal NAK 80

In the ultra-precision machining field, ferrous metal machining is an important and practical research topic. However, lubricant effects, especially in tool wear reduction, have yet to be researched regarding the single-point diamond turning of ferrous metals. In this research, tool wear patterns, chip characteristics, and surface topography are investigated through cutting experiments that implemented two lubricant conditions, ordinary dry machining (ODM) and machining with minimum quantity lubrication (MQL), to determine the eco-friendly cutting condition effects on cutting performance in the diamond turning of NAK 80. Results show that MQL conditions achieve a higher tool wear rate than ODM. Furthermore, tool selection and lubricant components are also explored. The results, which tool wear was significantly worse under the MQL conditions than under the ODM conditions, are neither accidental nor related to the lubricant composition. Under the ODM conditions, the machined surface micro-hardness is higher and the cutting chips are both more complete and stable. Results suggest that chemical aspects caused the essential tool wear under the MQL conditions and that chemical tool wear is greater under the MQL conditions than under the ODM conditions. This indicates that the presence of lubricant is the root cause of catastrophic tool wear under the MQL conditions.