To reduce tool wear and improve surface quality in machining hard and brittle materials, grinding experiments are conducted on monocrystalline silicon using an electrochemical discharge assisted micro-grinding (ECD-MG) tool. Morphological evolutions are tracked and micro elements are analyzed on abrasive grains to understand tool wear mechanisms in ECD-MG process. Analyze the impact of micro-grinding tool wear on grinding force and workpiece surface quality, and based on the equivalent cutting load of a single abrasive grain and the wear rate, a dynamic evolution equation of micro-abrasive wear was established. The study shows that in ECD-MG process, four main tool wear mechanisms are grain abrasion, grain fracture, grain shedding and binder wear. Compared with conventional micro-grinding, ECD-MG reduces the occurrence of abrasive fracture and abrasive shedding, reduces the reduction in the diameter of the micro-grinding tool and the grinding force caused by abrasive wear, reduces the average edge fragmentation width of the grinding micro-groove, enhances the overall surface quality of the workpiece. The above research provides a theoretical foundation and technical support for extending the service life of tools in ECD-MG process.

The small arc-shaped CVD diamond roller wheel has broad application prospects in the preparation of micro-structured cutting tools. However, CVD diamond material has good wear resistance, which makes it extremely difficult to dress its small arc-shaped profile. In this work, the oblique line interpolation tangential envelope method is proposed to dress the small arc-shaped CVD diamond roller wheel. This method utilizes the squeezing contact points of two rotating wheels on the dressing path to form the required small arc-shaped profile. This can simultaneously avoid uneven loss of the tool wheel and interference with the installation accuracy of the machine tool, improving the dressing precision of arc-shaped profile. The profile errors caused by different machine tool motion axis are analyzed. The corresponding profile error prediction models have been established. In order to improve the truing accuracy of CVD diamond roller wheel, a segmented arc compensation method is proposed. Finally, femtosecond laser processing technology is used to achieve sharpening of CVD diamond roller wheel. The abrasive particles have a suitable blade height to facilitate the excellent grinding performance of the roller wheel.

As a key material for next-generation aero-engine components, the surface layer quality of a GH4169 superalloy after machining directly determines the wear performance of critical parts. This study focused on the tribological behaviour of GH4169 superalloy workpiece prepared by longitudinal torsional ultrasonic vibration-assisted milling (LTUVAM) over a wide temperature range. First, the surface topography and microstructural characteristics of milled specimens of conventional milling (CM) and LTUVAM were characterized. Subsequently, the effects of ultrasonic amplitude, sliding load and test temperature on the characterization parameters of wear resistance were summarized. The wear behaviours of the dual friction system, including a milling workpiece and friction ball, at room/high temperatures were investigated. Additionally, based on the microstructural characteristics of the milled specimen, the sliding wear mechanism of the dual friction system at room/high temperature was elucidated, along with the mechanism for enhancing surface layer wear resistance. Research findings indicate that high-temperature conditions promote thermal and osmotic transfer between the specimen and friction balls, increasing adhesive, oxidative wear and element transfer during sliding. The main forms of wear on CM and LTUVAM specimens at room/high temperatures are abrasive, adhesive, delamination, oxidative wear and element transfer. The LTUVAM specimens exhibited higher wear resistance compared to those prepared by CM, owing to the inhibition of inter-surface friction node growth (by the uniform ultrasonic vibration texture) and sub-surface crack nucleation and extension (by the refined surface layer microstructure). Results provide theoretical support for improving the wear resistance of nickel-based superalloy components under extreme conditions.

Bone grinding often causes excessive force and thermal damage due to the heterogeneous nature of bone tissue. To reduce mechanical and thermal loads in conventional bone grinding (CBG), this study proposes a laser-assisted bone grinding (LABG) method using laser ablation as surface pretreatment. A two-dimensional thermal model was established to predict ablation depth and the thermally affected layer. Constant-depth scratch tests and comparative grinding experiments were conducted to investigate surface integrity and material removal behavior. Results showed that the laser-induced groove structure reduced the tool-workpiece contact area, decreasing the average grinding force by 69.35% while maintaining temperatures below the 50 degrees C biological threshold. The laser-pretreated layer promoted brittle-dominated removal, where thermal microcracks interacted with grinding-induced cracks to facilitate fracture-based material removal. The proposed LABG method provides an effective approach for low-damage and high-efficiency bone machining in orthopedic applications.

Electrochemical Discharge Machining (ECDM) has emerged as a highly effective technique for micro-hole fabrication in hard, brittle insulating materials. However, the critical challenge of synchronizing the Tool Feed Rate (TFR) with the Material Removal Rate (MRR) often leads to detrimental tool-workpiece contact, resulting in tool electrode fracture and workpiece damage. To address this fundamental limitation, this study introduces an innovative current signal-based approach for tool-workpiece contact detection, integrating a Residual-Bidirectional Long Short-Term Memory network with Attention mechanism (Res-BiLSTM-A) and Bayesian Optimization Meta-Learning (BO-meta-learning) to develop an intelligent detection method. The proposed method employs BO-meta-learning for optimal training dataset selection, achieving precise contact state identification during the general hole machining process. Experimental validation through force sensor measurements confirmed the detection accuracy of the proposed method. Comparative analysis demonstrates significant performance enhancements of the Res-BiLSTM-A model over conventional grid search models, with improvements of 1.58-3.16 % in accuracy, 1.87-3.18 % in F1-score, and 0.05-4.38 % in AUC values. The timeline of the contact process revealed that discharge-induced forces precede physical contact, enabling preemptive detection through current signal analysis. These findings not only resolve a persistent challenge in ECDM but also establish a critical foundation for developing next-generation closed-loop control systems in electrochemical discharge machining.

Laser etching technology has the advantages of high efficiency and high precision, and can be used to etch micro textures on the surface of PCD materials. However, nanosecond laser etching has serious thermal damage defects, significantly reducing tool durability. In this work, spray assisted laser etching is regarded as a promising new method. The objective of this study is to investigate experimentally the groove morphology of PCD materials under different laser pulse energies and input energy densities. Firstly, the spray assisted laser etching technology is theoretically analyzed, and its processing advantages are shown from the material removal mechanism. Then, the influence of average power, repetition rate, scanning speed, scanning frequency, and pumping water volume on the groove morphology was studied through single factor experiments. By combining appropriate process parameters, a substantial amount of material with thermal damage should be removed. In addition, it is found that spray assisted laser etching effectively inhibits the formation of recast layer, reduces the disorder structure of graphite, and significantly improves the processing quality. Finally, based on the above optimized process parameters, a variety of micro textures without recast layer and with complete structure were successfully obtained by using this new technology. The above research results indicate that the spray assisted laser etching technology can effectively reduce or eliminate the thermal damage defects on the surface of PCD materials.

In the ultrafast laser stealth dicing of silicon carbide wafers, achieving both high efficiency and superior quality remains a significant challenge in wafer manufacturing. To address this, this study innovatively proposes applying laser power modulation to multi-layer modified stealth dicing of 4H-SiC, aiming to enhance cross-section quality while maintaining processing efficiency. Experiments reveal that multi-layer modification dicing utilizing self-focusing effects achieves over fourfold efficiency gains compared to single-layer modification, yet results in significantly increased cross-section roughness. Molecular dynamics simulations reveal that this phenomenon stems from edge thermal stress concentration caused by uneven heat dissipation. Building upon this insight, the proposed laser power modulation technique achieves a substantial reduction in cross-section roughness under optimized parameters, thereby synergistically enhancing both efficiency and quality. This study offers valuable insights and practical methodologies for high-quality and high-efficiency SiC wafer stealth dicing.

Ultra-high-speed cutting (UHSC) has emerged as a transformative manufacturing technology aimed at overcoming the long-standing machining challenges associated with high-performance difficult-to-machine composites (HPDMCs). These materials—comprising silicon-based, metal matrix, and carbon fiber-reinforced polymers—are critical to strategic sectors such as aerospace and high-end equipment. This review adopts a distinctive “material-tool-process-equipment” synergistic innovation framework as its core analytical lens. Within this framework, it systematically outlines advances in UHSC, including the fundamental mechanisms of damage suppression and surface integrity enhancement under ultra-high strain rates. Innovative process methods such as laser-assisted and ultrasonic-assisted machining are examined in detail. This review also provides a mechanistic analysis of two key enabling technologies—tool micro-texturing and functional coatings—highlighting their roles in interfacial tribological regulation and physicochemical protection. Furthermore, dedicated equipment systems and stability optimization strategies essential for technological implementation are presented and evaluated. By synthesizing the current state of the field, this review identifies persistent bottlenecks and, guided by the proposed framework, suggests targeted future research directions: deep integration of smart manufacturing technologies, development of synergistic multi-energy-field processing, and enhanced adaptability to extreme service environments. This work not only consolidates the current knowledge in UHSC but also outlines a clear pathway for its evolution into a fully autonomous, efficient, and reliable manufacturing paradigm.

How to perform a laser welding is crucial to assure the quality of welds on magnesium alloys, and the challenges are the suppression of bubble generation and the reduction of pore defects. In this paper, hybrid blue-IR laser welding (HBI-LW) is proposed to improve the stability of a molten pool and keyhole; HBI-LW is produced by using dual coaxial lasers that have different wavelengths and spot diameters. A multi-physics heat flow model is developed to analyze the effect of composite heat sources on porosity quantitatively. The combined volumetric heat source model has been verified experimentally. The experiments show that when the laser power is 1800 W and the power of HBI is increased to 600 W, the porosity is formed at a lower level of about 0.5 %. The results are aligned well with that from numerical simulations on the proposed volumetric heat source model. In comparison with LW, HBI-LW is able to generate a larger melt pool and plasma plume and to smoothen the rear wall of a keyhole. This regulates the flow of the molten pool, suppresses the keyhole closure, and reduces the occurrence of keyhole collapse effectively. The dynamics of the keyhole and the forming mechanism of pores are investigated. This research provides theoretical and practical guides to suppress pore defects in laser welding on magnesium alloy.

Ultrafast laser slicing is a promising method for slicing silicon carbide (SiC) wafers. However, the surface quality of the sliced wafer significantly impacts subsequent processing efficiency and material utilization. This paper investigates the effects of laser processing parameters on the surface quality of sliced 4H-SiC wafers and proposes a gradient energy-modulation multi-pass strategy. The results indicate that excessive pulse energy or scanning passes degrade the cracked layer morphology and increase surface roughness. Compared to constant-energy multi-pass scanning, gradient energy modulation with Delta Ep = 1.7 mu J improves surface quality. The area of the modified region and the boundary defect region decreased by 28 % and 20 %, respectively. By using the gradient energy-modulation scanning strategy, a 5 x 5 mm sample with an average Sa = 224 nm was obtained, and the surface roughness was reduced by 80 %. Boundary defects are refined from micron-scale cracks to nanometerscale voids. This study offers valuable insights and practical methodologies for high-quality SiC wafer slicing, minimizing material loss and enhancing downstream efficiency.

Grinding-induced white and dark layers play a critical role in determining the surface integrity of hardened AISI 52100 steel. However, the atomic-scale formation mechanisms remain inadequately characterized. This study systematically investigated carbon redistribution governing the differentiation of superficial and subsurface layers, focusing on the interplay between carbon atom migration and localized structural transformations. Through FIB-TEM characterization, a competitive grain refinement pathway was deciphered within the white layer, and its nanocrystallization model was established. This model reflects adaptive grain evolution driven by dislocation slip, offering new perspectives on surface integrity regulation via multiscale analysis. Results revealed that grinding-induced superficial re-austenitization followed by rapid cooling caused carbon saturation in alpha-Fe lattices, which generated asymmetric distortion that promoted twinning-dominated martensitic transformation and formed a hardened white layer composed of acicular martensite grains. Subsurface regions with insufficient thermal input for austenitization underwent carbon desolvation during cooling, triggering significant relaxation of lattice distortion. This process enabled high-temperature tempering that generated a softened dark layer of over-tempered martensite and ferrite composites. Under the thermomechanical coupling effect, dislocation slips were accumulated within the workpiece surface microstructure. This led to a nanocrystallization model that progressively transitioned from dynamic recovery (DRV) to major continuous dynamic recrystallization (cDRX) supplemented by minor discontinuous dynamic recrystallization (dDRX). Meanwhile, the pinning effect of carbide particles enhanced dislocation proliferation and cross-slip. The synergistic interactions among these mechanisms resulted in substantial grain refinement down to the nanoscale. These findings provide valuable insights for optimizing grinding processes and improving the performance of machine elements.

Additive manufacturing of hard TiC-based cermets typically employs a high-energy beam as the energy source but suffers from high residual stress and microcracks. Herein, we propose an economical additive-manufacturing process for TiC-based cermets using powder extrusion printing (PEP) combined with pressureless sintering, which overcomes inadequacies such as extensive residual stress and microcracks. Complex cermet parts with high densities are successfully fabricated, thereby experimentally demonstrating the feasibility of this method. The as-produced TiC60(Ni88Fe12)40 composites exhibit a typical core-rim structure, which plays an important role in improving the interfacial bonding ability. The sintering temperature has a significant impact on the microstructure and mechanical properties. The flexural strength and microhardness increase first and then decrease at temperatures ranging from 1390 to 1430 degrees C. Optimum mechanical properties are achieved at 1410 degrees C with flexural strength and microhardness of 1013 +/- 17 MPa and 965 +/- 18 HV0.2, respectively. The additive-manufactured cermets exhibit superior abrasive resistance and the main abrasive mechanism is adhesive wear accompanied by oxidative wear. The good wear resistance is attributed to the high hardness of the TiC phase and the lubricating effect of the abrasive debris.

To enhance the strengths of welds on AZ31B Mg alloy, silicon carbide (SiC) nanoparticles can be added in welds to improve mechanical properties of welds. However, SiC nanoparticles have high-level of surface energy, the physical properties of SiC nanoparticles are significantly different from Mg alloy, and these tend to cause the instability of a molten pool and a keyhole in laser-welding. This study proposed to modulate the power of an oscillating laser and control the temporal and spatial distribution of laser energy to strengthen welds when SiC nanoparticles are applied to join AZ31B Mg alloy. The effects of power modulation on macroscopic morphology, microstructure, and mechanical properties of welds were investigated systematically. The experiments showed that an oscillating laser with the modulated power has not only reduced various defects including spatters, weld beads, and humping significantly; but also decreased gas porosities in welds and eliminated an agglomeration of nanoparticles. At a modulation frequency of 150 Hz, the average size of grains was refined from 24.30 to 5.87 μm, and the maximum intensity at the 0001 direction of texture had a reduction over 86%. By comparing with the mechanical properties of base materials, the ultimate tensile strength was increased to 239 MPa (96.3%) and the elongation at the fracture point reaches 12.75% (53.5%). By comparing the welds by the laser welding without (i) adding nanoparticles and (ii) power modulation, the proposed method has increased the tensile strength by 12.7% and 10.1% and the elongation by 45.9% and 20.9%, respectively.

Grinding is widely utilized in minimally invasive surgery due to its handleability and high precision. However, the substantial heat generated during the grinding process can lead to localized temperature increases, which cause thermal damage to surrounding healthy tissues. This study investigates the temperature distribution in the variable-depth reciprocating grinding process by developing a heat flux density model for the spatially irregular grinding contact surface. A User Defined Function (UDF) subroutine was developed to numerically simulate temperature distribution based on this heat flux density model. To validate the model, bone grinding experiments were conducted under various spindle speeds and cutting depths, with temperature measurements taken from the bone. The simulation results demonstrated high accuracy in experimental temperatures. Additionally, numerical simulations were performed to visualize the thermal damage range during bone grinding. The findings indicate that, under specific grinding conditions-such as a cutting depth of 0.2 mm at 10,000 rpm and 0.1 mm at 30,000 rpm-the thermal damage depth is relatively shallow, measuring only 0.07 mm. These results provide valuable insights for orthopedic surgeons regarding the influence of grinding parameters on bone temperature and establish a solid foundation for selecting optimal grinding parameters in orthopedic robotic systems for clinical applications.

Engineering ceramics have excellent properties such as high hardness and strength, resistance to high temperature, wear and corrosion, However, these ceramics also pose great challenges to processing techniques. A novel method of powder-mixed electrochemical discharge-drilling hybrid machining (PMECDDM) for alumina ceramics was proposed in this paper. The thermal removal mechanism of alumina ceramics during the hybrid machining process were analyzed. The temperature distribution on alumina ceramics under the action of the single-pulse electrochemical discharge was obtained based on a thermal-fluid coupling multiphysics simulation model. The axial force during the material removal process in mechanical drilling (MD) was comprehensively analyzed. Experiments were conducted under constant force feed condition to investigate the micro-hole machining performance of alumina ceramics by different machining methods. Experimental results revealed that a new form of discharge was generated after the introduction of the micro copper powder into the electrochemical discharge-mechanical drilling hybrid machining process, which increased the local discharge energy and strengthens the softening effect of the discharge on alumina ceramics. Compared to MD, the machined surface of PMECDDM exhibited fewer brittle fracture areas, resulting in improved surface quality. Compared with the conventional electrochemical discharge-drilling hybrid machining (ECDDM), the machining efficiency of PMECDDM was increased by approximately 47%.

Aiming at the technical difficulties of laser overlap welding of Al/Cu dissimilar metals,a new infrared-blue hybrid laser welding process was proposed.Laser welding of the overlap joints of 5052 aluminum alloy and T2 copper with thickness of 1 mm was carried out.The effects of different blue laser powers on the weld appearance,microstructure and mechanical properties of the joints were investigated.The results showed that the convection diffusion of copper elements from the lower copper plate to the upper aluminum plate could be weakened by using infrared-blue laser hybrid welding process with a blue laser power in the range of 0～500 W.With the increase of blue laser power,the mixing degree of molten copper and aluminum was increased,resulting in more brittle Al-Cu intermetallic compound(IMC)phases.Generates the following phases in the order from the copper side to the aluminum side,ϒ2-Al4Cu9,AlCu,θ-Al2Cu,α-Al+Al2Cu eutectic structure and Al/Cu eutectic structure.Among these,Al2Cu was the primary IMC phase at the interface layer of the joints.When the infrared laser power was 1050 W and the blue laser power was 300 W,the shear resistance of the joint reached up to 795.51 N.The joint was broken at the heat affected zone(HAZ)of the upper aluminum plate with a ductile fracture mode.

Herein, TiC/Fe-based alloys are melted and deposited on a 45-steel substrate by using an oscillating laser with an 8-shaped trajectory. Four samples are prepared to investigate the phase changes and microstructure characteristics using laser cladding under different oscillation frequencies. The microhardness, wear resistance, and electrochemical corrosion performance on both substrate and coatings are thoroughly evaluated. The results show that with TiC particles uniformly distributed throughout the coatings, the cladded coatings primarily composed of alpha-Fe, (Cr, Fe)7C3, M2B (Cr, Fe), and TiC phases contribute to refined grains and enhanced mechanical strength; additionally, an increase in oscillation frequency leads to further grain refinement, which significantly improves the microhardness of coatings; however, higher hardness does not guarantee better wear resistance; the presence of cracks can actually decrease the coating's durability against wear. It is found that the coating with an oscillation frequency of 200 Hz not only achieves the best wear resistance, but also exhibits excellent electrochemical performance.

This study presents a comparative analysis of the similarities and differences in the microstructure characteristics between ground and laser-quenched metamorphic layers on the AISI 52100 steel, revealing the respective impacts of thermal and mechanical effects on the microstructure evolution of metamorphic layers (i.e. white layer (WL) and dark layer (DL)). The results show that both thermal and mechanical effects result in grain refinement within WL. However, the increase in the proportions of sub-grain boundaries (SGBs) and low-angle grain boundaries (LAGBs) is caused by the mechanical effect, irrespective of the thermal effect. Furthermore, in addition to the mechanical effect, the thermal effect is also responsible for increased dislocation density within WL. The thermal effect causes the partial dissolution of carbides, while the mechanical effect results in the deformation and refinement of carbides in WL. In the DL, the thermal effect coarsens grains through grain boundary migration, accompanied by forming carbides due to the precipitation of C atoms. The dislocation density and the proportions of SGBs are reduced. However, the influence of the mechanical effect on the microstructure alterations of the DL is negligible. The hardness of the ground WL is increased by approximately 49.1 %, and such an increase is attributed to three factors: solid solution strengthening due to thermal effect, dislocation strengthening due to mechanical effect, and grain boundary strengthening due to thermal and mechanical effects. The thermal effect results in the formation of over-tempered martensite in the subsurface layer, reducing the hardness of ground DL by approximately 35.4 %. The results provide theoretical guidance for controlling the generation or utilization of metamorphic layers on AISI 52100 steel.

Objectives:During the grinding process of hardened bearing steel,the surface undergoes secondary quenching and severe plastic deformation,resulting in a metamorphic layer that differs significantly from the matrix mi-crostructure.The white layer,in particular,considerably influences the mechanical properties,fatigue strength,and ser-vice life of components.This study systematically characterizes the grinding-induced metamorphic layer using multiple microscopic techniques and evaluates its potential beneficial or detrimental effects on material performance through dry sliding friction and wear tests.Methods:Large-depth grinding parameters ware employed to generate a distinct meta-morphic layer on the material surface.The microstructure,morphology,and phase composition of the layer are charac-terized using optical microscopy,scanning electron microscopy(SEM),and micro-area X-ray diffraction(XRD).The microhardness distribution from the surface to the matrix is precisely measured using a semi-automatic Vickers micro-hardness tester to quantify grinding-induced hardness gradients.Finally,the friction and wear behaviors of samples with and without the metamorphic layer are compared.Wear scar morphology and mechanisms are examined using ultra-depth-of-field 3D microscopy and SEM to evaluate the effect of the metamorphic layer on wear resistance.Results:Un-der large-depth dry grinding conditions with a depth of cut of 40 μm,a pronounced white layer forms on the surface of hardened GCr15 bearing steel.This layer consists of fine-grained martensite,retained austenite,and carbides formed via grinding-induced secondary quenching,leading to a significant increase in microhardness,with a maximum value of 1 041 HV.This structural change also contributes to higher density and certain corrosion-resistant properties.Beneath the white layer,a dark layer forms due to tempering transformation caused by grinding thermal cycles,resulting in ma-terial softening with a minimum microhardness of 501 HV.In dry sliding wear tests under a constant load of 50 N,the friction coefficient of the white-layer sample is 0.22,lower than that of the matrix sample(0.34),and the friction pro-cess is more stable.The reduction in the friction coefficient is attributed to the smoother and flatter surface of the white layer,which reduces the actual contact area and consequently diminishes adhesion and ploughing effects,thereby enhan-cing wear resistance.Furthermore,the high hardness of the white layer enables effective resistance to deformation and material loss even under high loads and sliding speeds.The primary wear mechanisms of the white-layer sample are mild adhesive wear,abrasive wear,and oxidative wear.In contrast,the matrix sample exhibits severe abrasive wear,ox-idative wear,and delamination wear due to fatigue,resulting in more substantial material loss.Conclusion:The grind-ing-induced metamorphic layer,resulting from the combined effects of grinding heat and plastic deformation,consists of a white layer,a dark layer,and the matrix from the surface inward.The white layer exhibits significantly higher hard-ness than the matrix,reaching a maximum of 1 041 HV,while the dark layer shows softening relative to the matrix,with a minimum hardness of 501 HV.In terms of friction and wear performance,the white-layer sample demonstrates a lower friction coefficient and superior surface quality compared to the matrix sample,indicating that the formation of the white layer enhances the wear resistance of the component surface.