The resin-bonded spherical diamond wheel is widely used in arc envelope grinding, where the demands for form accuracy are high and the form truing process is challenging. In this paper, on-machine precision form truing of the resin-bonded spherical diamond wheel is accomplished by using a coarse-grained diamond roller, and in-situ measurement of the form-truing error is conducted through a laser scan micrometer. Firstly, a novel biarc curve-fitting method is proposed based on the in-situ measurement results to calculate the alignment error between the diamond roller and the spherical diamond wheel. Then, on-machine precision form truing of a D46 resin-bonded spherical diamond wheel is completed after alignment error compensation. The in-situ measurement results show that the low-frequency form-truing error is approximately 5 μm. In addition, the actual form-trued diamond wheel has been employed in grinding a test specimen, and the resulting form accuracy is approximately 1.6 μm without any compensation. The ground surface profile shared similar characteristics with the roller-trued diamond wheel profile, confirming that the diamond roller truing and in-situ measurements methods are accurate and feasible.

The ultraprecision machining of diamond presents certain difficulties due to its extreme hardness. However, the graphitization modification can enhance its machinability. This work presents an investigation into the characteristics of the graphitization modification in polycrystalline diamond induced by a nanosecond pulsed laser. In this paper, the morphology of microgrooves under laser modification was observed, material deposition and graphitization in different regions were researched, and the regularities of microgrooves at different laser powers were obtained. A molecular dynamics (MD) simulation was carried out to reveal the mechanism behind graphitization modification; when the pulse laser acts on the diamond surface and the temperature rises to the critical temperature of graphitization, the graphite crystal nuclei form and grow, resulting in the graphitization modification. It was confirmed that the existence of grain boundaries (GBs) contributed to the graphitization of polycrystalline diamond during laser modification. It was predicted that a lower laser power could cause a higher proportion of graphitization. The results of ablation thresholds and the effect of the defocusing position on the graphitization of diamond showed that for a fixed laser power, the highest graphitization ratio could be obtained when the defocusing quantity was optimized. Finally, the results of precision grinding experiments verified the feasibility of using laser graphitization pretreatment to improve the efficiency and quality of precision grinding.

Ultra-precision milling with an aerostatic high-speed spindle and a single-crystal diamond micro-tool is promising for the fabrication of miniaturized complex parts. While tool chatter occurring in milling processes has a substantial effect on the machined surface formation, a fundamental understanding of the tool chatter behavior in ultra-precision milling is essentially required for achieving an ultra-high surface finish. In this paper, through a combination of finite element simulations and experimental validations, the machining mechanisms of the ultra-precision diamond micro-milling of a copper workpiece are revealed, in which the tool chatter behavior and its correlation with the machined surface morphology are emphatically studied. Specifically, the correlation between the tool chatter and the transient depth of cut is analytical established. Subsequently, we first establish a finite element model of diamond micro-milling with the consideration of milling tool deformation and material removal to reveal the tool chatter behavior during the milling process. Furthermore, a corresponding micro-milling experiment is also conducted to validate the simulation results in terms of the milling force, chip profile and morphology of machined surfaces. Finally, the effect of spindle speed on the milling process in particular tool chatter is investigated by FE simulations, through which a linear relationship between the spindle speed and microscopic roughness Rz of a machined surface is obtained. The research findings provide a theoretical basis for understanding the origination of tool chatter in the diamond micro-milling process, as well as the rational selection of machining parameters for suppressing the tool chatter.

Nanocrystalline diamond (NCD) is regarded as a highly promising composite engineering material owing to its superior mechanical properties. Surface texturing significantly enhances the surface performance of NCD. Given the unique inherent combination of hardness and brittleness in NCD, laser ablation emerges as a critical method for fabricating surface microstructures. However, the research on laser-induced surface texturing of NCD remains limited. This study experimentally investigated the characteristics of nanosecond laser-ablation-induced graphitization in NCD and provided an in-depth analysis of the laser ablation mechanism, aiming to guide the optimization of NCD surface microtexture manufacturing. Specifically, we conducted systematic nanosecond pulse laser ablation experiments on NCD samples and utilized Raman spectroscopy to qualitatively characterize the graphitization within microgrooves and across the entire ablated surface. The effects of the laser scanning speed, power, defocus level, and scanning interval on the graphitization extent and morphological characteristics were systematically investigated, identifying the single-factor optimal parameter set for maximizing graphitization. Through single-factor experimental analysis, the findings of this study provide foundational data for subsequent multivariate-coupled optimization and offer theoretical support for enhancing the surface properties of NCD through microtexturing via laser ablation.

To improve the ultrasonic energy and realize far-field ultrasonic abrasive machining of complex surfaces, a spherical-array-focused ultrasonic abrasive machining system was established. By combining ultrasonic field simulation, detection and a single-factor experiment, the influences of the ultrasonic generator current, abrasive concentration, and particle size on the material removal properties and surface quality evolution of quartz glass were investigated. When the current was less than 0.4 A, the material removal showed plastic removal at the nanoscale. When the current was more than 0.5 A, the cavitation phenomenon formed micron-scale impact removal traces on the workpiece surface. The increase in abrasive concentration increased the impact density and material removal rate, while excessive abrasive concentration increased the impeding effect between abrasive particles and reduced the material removal rate. Moreover, the increase in abrasive particle concentration enhanced heterogeneous cavitation nucleation, promoted the removal of abrasive impact materials under the action of a cavitation jet, and inhibited the removal of direct surface cavitation. The abrasive particle size affects the heterogeneous cavitation nucleation and the acceleration of the cavitation jet on abrasive particles, which affects the material removal rate and surface quality. By controlling the energy of the focused ultrasound and abrasive parameters, the plastic or brittle domain removal of quartz glass can be achieved at the micro- and nanoscales.