High-speed rotary ultrasonic elliptical milling (HRUEM), as a novel ultrasonic vibration cutting method, has been introduced in milling the alloy Ti-6Al-4V. The application of ultrasonic vibration in high-speed milling can help open the cutting contact area intermittently. New cutting effects will happen with full use of the separation effect brought by ultrasonic vibration and the cooling effect brought by a high-pressure coolant (HPC). On the basis of that, this paper firstly introduces HPC into HRUEM of Ti-6Al-4V in the open literature and analyzes the tool-workpiece separation cooling mechanism in HRUEM, including kinematic analysis of tool tip trajectories, tool-workpiece separation principles and high-pressure coolant effects. We have conducted a comprehensive experimental study and the results show when HPC is increased to 200 bar, compared to conventional milling (CM), the tool life in HUREM can be extended by 6.6 times at 80 m/min, 4.2 times at 120 m/min and 2.4 times at 160 m/min. The maximum material removal volume (MRV) for a given new end mill in HRUEM is increased by 657% approximately. When the cutting speed is 80 m/min, the cutting temperature of the workpiece in HRUEM is reduced by 24.1% compared to that of CM. By applying the combination of HPC and tool-workpiece periodic separation, we can significantly enhance the cooling and lubrication efficiency in HRUEM and also inhibit the tool wear mode of adhesive wear typically occurred in CM.

To overcome the challenges of processing soft-brittle potassium dihydrogen phosphate (KDP) crystals, this study proposes a back-propagation (BP) neural network model for the rapid prediction of the ion beam removal function using Faraday cup scanning data (a method that measures the spatial distribution of ion beam current density). By correlating current density measurements with point etching experiment results, the model accurately maps both the linear relationship (R² = 0.98) between peak removal rate and peak current density, and the non-linear relationship between the full width at half maximum (FWHM) of the beam and the removal function. The predicted removal function demonstrates high accuracy, with a volume removal rate error of just 2.56% compared to experimental results. Furthermore, this method drastically reduces calculation time from approximately 2 h (required by the conventional point-etching experiment, which involves iterative vacuum cycling, etching, and ex situ interferometry) to just 2 min, significantly improving efficiency. Applied to the ion beam polishing of a 50 mm × 50 mm × 10 mm KDP crystal, the model proved highly effective. The surface figure error was corrected from an initial 0.298λ peak-to-valley (PV) and 0.0496λ root-mean-square (RMS) to 0.167λ PV and 0.036λ RMS, where λ (632.8 nm) is the wavelength of the He-Ne laser used for interferometric surface measurement, achieving a convergence ratio (defined as the ratio of initial PV to final PV) of 1.78. This research provides a high-efficiency, high-precision technical solution for manufacturing KDP components for inertial confinement fusion (ICF) applications.

To address the issues of heat accumulation and potential thermal damage during radio-frequency (RF) ion beam machining of KDP crystals, an energy deposition model and a temperature field model were developed based on Sigmund’s sputtering theory, a Gaussian beam distribution model, and heat conduction theory. Combined with the Monte Carlo method, the effects of incident energy, incident angle, and ion species on the disturbed layer depth and sputtering yield were systematically investigated. Furthermore, the influences of beam divergence angle and deflection angle on the surface energy deposition density distribution were analyzed. On this basis, the evolution of the temperature field and thermal stress field in KDP crystals under both stationary and linearly moving Gaussian surface heat sources was numerically simulated. The results indicate that the proposed model can effectively characterize the thermal response during ion beam machining of KDP crystals. The disturbed layer depth, sputtering yield, and energy deposition density distribution exhibit pronounced sensitivity to processing parameters. Under a stationary heat source, significant local heat accumulation and stress concentration tend to occur on the material surface. In contrast, a moving heat source can mitigate excessive temperature rise at a single location to some extent, although it also produces a heat-affected zone extending along the scanning path. These findings provide a theoretical basis for the optimization of low-damage RF ion beam machining parameters for KDP crystals.