High-sensitivity and rapid-response measurements of micro zone cutting temperature are crucial for characterizing and optimizing machining states in the ultra-precision cutting process. This innovative method uses a locally boron-doped diamond (LBDD) tool itself as the sensor for in-process measurements of cutting temperature. However, the heterogeneity of boron doping and the resulting lattice distortions considerably affect the mechanical properties and temperature-sensing performances of the tool. In this work, optimized synthesis processes and structural designs for LBDD tools that function as self-sensing cutting temperature devices were proposed. Annealing treatments under high-pressure conditions were conducted to promote the diffusion and ionization of boron multimers in the boron-doped diamond zone, thereby enhancing the crystal quality and semiconductor electrical properties of the LBDD. Various LBDDs with thin-layer temperature-sensing structures of different doping concentrations and thicknesses were synthesized. The optimal components and structures were identified as the temperature-sensing cutting tool through comparative analyses of temperature measurement capabilities and semiconductor properties. The selected tool was employed for in-process cutting temperature measurement during single-point diamond turning of copper and carbon fiber. Results indicate that the LBDD tool can accurately monitor cutting temperature during steady cutting processes and identify the micromorphological features of the machined surfaces based on cutting temperature characteristics. These insights are pivotal for controlling cutting temperature and refining the ultra-precision cutting process.
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