Hang Gao

In the pursuit of achieving exceptional surface shape accuracy for MPCVD (Microwave Plasma Chemical Vapor Deposition) polycrystalline diamond wafers during the free abrasive lapping process, plane lapping based on rotary swing drive was employed in this study. The crux of this study lay in the development of a comprehensive kinematic model, scrutinizing the motion behavior of abrasive particles, and probing the influence of parameters on the uniformity of abrasive trajectories. The results show that the eccentricity, arc chord length and speed ratio affect the probability of track coincidence rate, and then affect the distribution uniformity. And then the verification experiments solidifying the reliability of our kinematic model and affirming the veracity of simulation results. The best surface shape accuracy ( PV) of the MPCVD polycrystalline diamond wafer was 2.3 μm under optimal parameters, representing a substantial advancement compared to the original lapping method, which only yielded a PV value of 8.4 μm. This study provides a promising method for high surface shape accuracy of MPCVD polycrystalline diamond wafers with large sizes.

In the realm of abrasive flow machining (AFM), precise finishing and maintaining dimensional accuracy have remained challenging due to non-uniformities in the AFM process and complexities associated with the abrasive media’s shear viscosity and wall slip behavior. By addressing these challenges, this study introduces a comprehensive framework, combining theoretical foundations, measurement techniques, and experimental setups. Utilizing capillary flow, a novel compensation strategy is incorporated within the Mooney method to counter entrance pressure drop effects. This enhanced capillary flow method emerges as a promising alternative to the conventional Cox–Merz empirical rule, enabling precise characterization of wall slip behavior and shear viscosity, particularly at elevated shear rates. The abrasive media exhibit a Navier nonlinear wall slip, as highlighted by the Mooney method. Rigorous verification of the proposed methodologies and models against supplemental experiments showcases a high degree of congruence between predicted and observed results, emphasizing their accuracy and broad application potential in AFM. This research illuminates the intricacies of the abrasive media’s behavior, accentuating the need for meticulous characterization, and provides a robust foundation for genuine modeling and predictions in material removal within AFM.