Abstract Plasma jet machining has emerged as a promising noncontact technique for high-precision surface processing, advantageously avoiding subsurface damage. However, jet instability significantly limits its effectiveness. To address this limitation, this study presents a systematic structural optimization of an inductively coupled plasma torch. A novel inclined inlet geometry is proposed to improve axial flow guidance, and the effects of inlet angle and excitation-to-nozzle distance on flow dynamics are investigated using three-dimensional multiphysics simulations. An image-processing method for quantifying jet stability is developed using three key metrics: centroid displacement, area fluctuation, and temporal superposition. A 5° inlet angle and a 5-mm excitation-to-nozzle distance significantly improved jet radial uniformity and thermal symmetry. Plasma polishing experiments further validated the optimized structure. Surface roughness measurements confirmed a substantial reduction in Sa roughness from 5.589 to 1.033 nm, achieving near-Gaussian removal functions with reduced variance and improved rotational uniformity. The material removal rate also exhibited enhanced stability, with the coefficient of variation decreasing to 3.92% from 6.43% for the original design. Furthermore, parametric analysis showed consistent performance across varying flow rates and power levels. These highlight the effectiveness of structural optimization in stabilizing plasma jets and improving material removal quality, providing practical insights for the advancement of plasma-based processing technologies.

Abstract The fabrication of freeform optical components is increasingly demanded in emerging technologies such as augmented reality, imaging systems, and compact spectrometers. Fast-tool-servo (FTS) diamond turning has become a promising solution for high-speed, high-precision machining of such surfaces. However, achieving nanometric form accuracy remains challenging due to servo-induced dynamic errors, particularly overshoot and control delay. This study proposes a feedforward methodology to predict and compensate for dynamics-induced form errors in long-stroke FTS systems. By capturing FTS position signals and applying normalized cross-correlation (NCC) analysis, a repeatable motion error referred to as the time-shifted following error (TSFE) was identified through time delay compensation of the servo. The three-dimensional map of TSFE was constructed and integrated into the tool path to compensate for the error before machining. Experimental machining test of a dual-sinewave freeform shape achieved peak-to-valley (PV) form error of 0.26 µm, which was a 56% reduction compared to without measurement compensation. The repeatability of the three-dimensional map of TSFE showed a standard deviation of 0.007 µm on the PV, which confirmed that the TSFE map has enough repeatability to be used as a pre-compensation dataset. Additionally, the FTS system had latent TSFE error regardless the spindle rotation rates. In this study the TSFE map derivation of system indicated approximately 0.5 µm PV. These findings establish a fundamental and broadly applicable framework for improving form accuracy in high-speed freeform optics manufacturing using FTS, contributing to the advancement of ultra-precision machining technologies.

Abstract Owing to the relatively low stiffness of the slide and the considerable deformation under support force, the fluid–structure interaction (FSI) phenomenon in aerostatic slides is generally pronounced. This phenomenon affects the performance of static pressure slides, particularly those with high load-carrying capacity and low stiffness. However, most existing methods for analyzing the effect of FSI on the stiffness of static pressure slides are iterative and computationally expensive. To address this issue, a novel direct method is proposed for evaluating the stiffness of static pressure slides while considering FSI. This method can quickly and precisely obtain numerical solutions. Furthermore, the accuracy of the proposed method is validated through experiments. Based on the developed FSI model, the effects of normal force and film thickness on the normal stiffness of aerostatic slides are also investigated.

Abstract Microtextured surfaces, such as those with groove, hole, or protrusion structures, are widely used in various industries for bonding dissimilar materials because of their anchor effect, which enhances adhesion and penetration with other materials. Although surfaces with grooves and protrusions are expected to show higher bonding strength, it is difficult to fabricate such hybrid structures using a material removal process or additive manufacturing. This study established a new burnishing method using a tool with preformed microgrooves at the tip to fabricate groove-with-protrusion structures on metal surfaces by plastic deformation. The tip of a ball-shaped polycrystalline diamond (PCD) tool was irradiated with a femtosecond pulsed laser to generate multiple trapezoid ten-micron scale grooves. Burnishing was then conducted on an oxygen-free copper surface to investigate the characteristics and mechanism of the burnishing-induced plastic deformation behaviors. The results showed that protrusions and grooves, which were several tens of micrometers in height and depth, were simultaneously produced along the tool path on the material surface. Tool sliding on the workpiece induced shear stress, which mainly triggered dislocation movement and plastic deformation enhancement. Cross-sectional observation revealed that grain elongation and refinement remarkably increased with the burnishing depth, indicating that the shear stress from burnishing produced refined grains that flowed and formed the protrusions. This research demonstrates the feasibility of a highly efficient method for simultaneously generating groove-with-protrusion structures with enhanced surface properties.

Micro/nanomotors present considerable potential in various fields, such as medical treatment, environmental remediation, and cell engineering. However, their restricted lifetime and issues in navigation control hinder their applications in cases requiring precise positioning without chemical fuels. Thus, we propose a tubular micromotor driven by external magnetic fields, enabling it to swim in water with accurate transport capabilities. The presented tubular micromotor incorporates a single-sided base, which increases the contact area to enable cargo delivery in liquid environments. The micromotor exhibits varied movement behaviors by applying different magnetic fields, and frequency modulation allows for control over movement velocity. Template-assisted electrochemical deposition is employed to achieve large-scale fabrication, which enables the construction of Ni–Au tubular micromotors with a single-sided base. In addition, the micromotor can trace a predefined path, which demonstrates its precise positioning ability. The cargo transport capability of the micromotor is further validated using polystyrene globules as cargo. This fuel-free tubular micromotor, which is driven by magnetic fields, provides a promising approach for precise cargo delivery. Its broad feasibility makes it suitable for various biomedical applications.

Abstract Microscale grooves and holes were fabricated in carbon fiber reinforced plastics (CFRPs) using femtosecond pulsed laser irradiation, and the characteristics and mechanisms of laser processing were investigated. The relationship between laser fluence and ablation depth was established by measuring the cross-sectional profiles of the microgrooves produced at different laser fluences. Furthermore, the effect of the angle between the edge of the micro holes and the carbon fibers was examined by analyzing the edges and wall surfaces of circular and rectangular holes. Experimental results revealed that the laser processing mechanism was strongly dependent on fiber orientation due to significant heat conduction along carbon fibers. The findings of this study contribute to a deeper understanding of the ultrashort pulsed laser processing characteristics and mechanisms for creating small holes in CFRPs and emphasize the possibility of drilling high-precision holes that can be used in the direct bonding of sensors/IC chips to CFRPs.

An optical glass array lens is an optical element arranged periodically to achieve imaging, light equalization, focusing, diffusion, collimation, sensing, and other functions. Precision glass molding offers high production efficiency, simple operation, high replication resolution, and low batch cost, which make it an effective method for the fabrication of glass array lenses. This study used D-K9 optical glass to research the precision molding of ring array lenses. The effects of varying molding temperatures, pressures, and times on the evolution of filling ratio and surface roughness (Sa) were investigated. Stress evolution and residual stress distribution in the lens during the glass molding process were studied via numerical simulation. The results indicate that molding temperature and molding pressure played crucial roles in determining the filling ratio and surface quality of the molded glass lens. At molding conditions of 590 °C/1 kN/30 s, the filling ratios and Sa of the molded glass ring array were approximately 99.5% and 11 nm, respectively. The maximum residual stress was observed near the surface edge of the molded glass array lens. This work provides effective guidance for the fabrication of glass array lenses.

In this study, a novel deposition technique that utilizes diethylzinc (C4H10ZnO) with H2O to form a ZnO adhesion layer was proposed. This technique was followed by the deposition of vaporized nickel(II) 1-dimethylamino-2-methyl-2-butoxide (Ni(dmamb)2) and H2 gas to facilitate the deposit of uniform layers of nickel on the ZnO adhesion layer using atomic layer deposition. Deposition temperatures ranged from 220 to 300 °C. Thickness, composition, and crystallographic structure results were analyzed using spectroscopic ellipsometry, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD), respectively. An average growth rate of approximately 0.0105 angstroms per cycle at 260 °C was observed via ellipsometry. Uniform deposition of ZnO with less than 1% of Ni was displayed by utilizing the elemental analysis function via SEM, thereby providing high-quality images. XPS revealed ionizations consistent with nickel and ZnO through the kinetic and binding energies of each detected electron. XRD provided supplemental information regarding the validity of ZnO by exhibiting crystalline attributes, revealing the presence of its hexagonal wurtzite structure.

Nickel is typically used as one of the main components in electrical contact devices or connectors. Nickel oxide (NiO) is usually formed on the surfaces of electrodes and can negatively impact system performance by introducing electrical contact resistance. The thermal, electrical, and transport properties of NiO, as a Mott insulator or a p-type semiconductor, can be altered by operating and environmental conditions such as temperature and stress/strain by contact. In this study, we investigate the fundamental material properties of NiO through the first-principle calculations. First, we obtain and compare the lattice parameter, magnetic moment, and electronic structure for NiO via the WIEN2K simulations with four different potentials (i.e., GGA, GGA + U, LSDA, and LSDA + U). Then, using the WIEN2K simulation results with LSDA + U potential that produces a highly accurate bandgap for NiO, we calculate the electrical conductivity and electrical part of the thermal conductivity of nickel and NiO as a function of temperature and carrier concentration through the BoltzTraP simulations. Systematic simulation results revealed that the electrical conductivity relative to the relaxation time for NiO increases with the carrier concentration, while it shows a slightly decreasing trend with temperature under a fixed carrier concentration. By contrast, the electrical part of the thermal conductivity shows an increasing trend considering carrier concentration and temperature.