High-performance diamond “Supertools” with extreme tool-life

Abstract

The use of diamond as a cutting tool is pervasive in modern ultra-high-precision machining applications, particularly for generating sub-micron accurate features through the Single Point Diamond Machining (SPDM) method. Beyond SPDM, diamond is also widely employed in contact profilometry (imaging), nanoindentation, nanoimpact, nanoscratching, and lithography applications. Interestingly, a particular type of diamond, commonly used in what the fabrication industry calls “supertools,” consistently demonstrates a lifespan up to 300% longer than that of standard diamond tools. Despite this remarkable performance, the reasons behind the enhanced durability of these unique diamond tools have remained unclear. This paper provides the first experimental explanation for the exceptional properties of these “supertools”. Using Fourier Transform Infrared Spectroscopy (FTIR), we establish that such diamond possess higher overall concentration of nitrogen, particularly Defect Type A (type IaA) and Defect Type C (type Ib). Counterintuitively, they also exhibit lower residual stresses, as revealed through cross-polar examination. Moreover, the diamond tip misalignment error, estimated using Laue backscattering analysis, was found to be insignificant in governing the tool wear resistance. These findings suggest that the wear resistance of natural diamonds can be predicted by screening for high levels of nitrogen defects (combination of Type A and Type C). This insight offers valuable potential for selecting superior diamonds for high-value manufacturing.