Jianguo Zhang

In recent years, digital manufacturing, high-energy-beam processing, and nano- and micro-scale fabrication have developed rapidly, extending the capabilities of modern engineering and broadening their practical application

The fused silica hemispherical resonator, a critical component in hemispherical resonator gyroscopes, requires exceptional surface integrity to ensure high quality factors (Q factors) and minimal frequency splitting. Ultra-precision grinding is commonly used for shaping such brittle materials, and the performance of the grinding wheel plays a crucial role in machining outcomes. This study integrates one-step forming with a bronze-bonded cup-shaped diamond grinding wheel and on-machine dressing techniques targeting both the cutting edge and wheel matrix. A systematic investigation from tool geometry to resonator performance is conducted. The radial runouts of the cutting edge and matrix are significantly reduced to 5.666 and 2 μm, respectively. This improvement leads to fewer surface defects and shallower grinding marks, yielding a surface roughness below 0.02 μm and reducing the peak-to-valley error by 73% to 85.27 nm. Geometric accuracies at the resonator level are improved, with circularities of the inner and outer hemispheres and concentricity reduced by 46.15%, 57.89%, and 28.57%, respectively. The Q factor of the resonator is improved to 3.17 × 107, while frequency splitting is reduced to 0.0156 Hz. These results confirm that simultaneous dressing enhances tool integrity, enabling high-quality surface generation and improved resonator performance. This study provides a viable approach for fabricating high-Q resonators.

A novel dual-axis piezoelectric system designed for elliptical vibration cutting (EVC) is reported. The system features a topology-optimized compliant mechanism for transmitting the motion of parallel-arranged stacked piezoelectric actuators (SPAs). Static and dynamic analyses of the mechanism were conducted using the solid isotropic material with penalization (SIMP) approach with hexagonal-element. A comprehensive optimization model was developed to guide the topological evolution, incorporating constraints related to resonance frequencies, motion coupling, fatigue durability, and manufacturability. The performance of the designed compliant mechanism was validated via finite element simulations. The fabricated prototype achieved strokes of $\mathbf{13.04}$ and $\mathbf{12.55}\,\boldsymbol{\mu}\mathbf{m}$ in two directions, respectively, with corresponding resonance frequencies of 4357 and 3178 Hz. A decoupled control strategy combining a proportional and integral (PI) controller and model-based feedforward compensation was implemented, yielding minimal inter-axis crosstalk. Trajectory tracking experiments demonstrated the effectiveness of the designed closed-loop system.

Calcium fluoride (CaF ₂ ) crystals are regarded as ideal materials for optical components due to their excellent ultraviolet (UV) transmittance and optical anisotropy.

In this paper, hierarchical micro/nano structures composed of periodic microstructures, laser-induced periodic surface structures (LIPSS), and nanoparticles were fabricated by femtosecond laser processing (LP). A layer of hydrophobic species was formed on the micro/nano structures through perfluorosilane modification (PM). The reflectivity and hydrophobicity’s influence mechanisms of structural height, duty cycle, and size are experimentally elucidated. The average reflectivity of the silicon surface in the visible light band is reduced to 3.0% under the optimal parameters, and the surface exhibits a large contact angle of 172.3 ± 0.8° and a low sliding angle of 4.2 ± 1.4°. Finally, the durability of the anti-reflection and superhydrophobicity is also confirmed. This study deepens our understanding of the principles of anti-reflection and superhydrophobicity and expands the design and preparation methods for self-cleaning and anti-reflective surfaces.

Polycrystalline ZnS is a typical infrared optical material. It is widely used in advanced optical systems due to its excellent optical properties. The machining accuracy of polycrystalline ZnS optical elements must satisfy the requirements of high-performance system development. However, the soft and brittle nature of the material poses a challenge for high-quality and efficient machining. In recent years, in situ laser-assisted diamond cutting has been proven to be an effective method for ultra-precision cutting of brittle materials. In this study, the mechanism of in situ laser-assisted cutting on ultra-precision cutting machinability enhancement of ZnS was investigated. Firstly, the physical properties of ZnS were characterized by high-temperature nanoindentation experiments. The result revealed an increase in ductile machinability of ZnS due to plastic deformation and a decrease in microhardness and Young’s modulus at high temperatures. It provided a fundamental theory for the ductile–brittle transition of ZnS. Subsequently, a series of diamond-cutting experiments were carried out to study the removal mechanism of ZnS during in situ laser-assisted cutting. It was found that the mass damage initiation depth groove generated by in situ laser-assisted cutting increased by 57.99% compared to the groove generated by ordinary cutting. It was found that micron-sized pits were suppressed under in situ laser-assisted cutting. The main damage form of HIP-ZnS was changed from flake spalling and pits to radial cleavage cracks. Additionally, the laser can suppress the removal mode difference of different grain crystallographic and ensure the ductile region processing. Finally, planning cutting experiments were carried out to verify that a smooth and uniform surface with Sa of 3.607 nm was achieved at a laser power of 20 W, which was 73.58% better than normal cutting. The main components of roughness were grain boundary steps and submicron pit. This study provides a promising method for ultra-precision cutting of ZnS.

Difficult-to-machine materials (DMMs) are extensively applied in critical fields such as aviation, semiconductor, biomedicine, and other key fields due to their excellent material properties. However, traditional machining technologies often struggle to achieve ultra-precision with DMMs resulting from poor surface quality and low processing efficiency. In recent years, field-assisted machining (FAM) technology has emerged as a new generation of machining technology based on innovative principles such as laser heating, tool vibration, magnetic magnetization, and plasma modification, providing a new solution for improving the machinability of DMMs. This technology not only addresses these limitations of traditional machining methods, but also has become a hot topic of research in the domain of ultra-precision machining of DMMs. Many new methods and principles have been introduced and investigated one after another, yet few studies have presented a comprehensive analysis and summarization. To fill this gap and understand the development trend of FAM, this study provides an important overview of FAM, covering different assisted machining methods, application effects, mechanism analysis, and equipment design. The current deficiencies and future challenges of FAM are summarized to lay the foundation for the further development of multi-field hybrid assisted and intelligent FAM technologies.