In next-generation wide-body aircraft, CFRP/Ti stack structures constitute essential components at critical airframe junctions, including flat-tail and wing-body docking regions. With the increasing size of aircraft, these stacks demand larger and deeper holes to ensure sufficient junction strength, which presents substantial challenges for conventional automated machining. Traditional drilling techniques often fail to satisfy the stringent requirements for tool robustness and hole integrity when processing large-diameter holes in multi-layer CFRP/Ti stacks. To overcome these limitations, this study introduces a novel large-diameter hole machining approach based on a gradual reaming strategy tailored for four-layer Ti/CFRP/CFRP/Ti stacks. Specifically, a series of specialized reaming tools featuring helix-stepped geometries is developed to enhance tool strength. Furthermore, two reaming strategies-distinguished by large and small material removal volumes-are proposed to ensure superior hole quality. Through experiments, the hole formation process, cutting-force fluctuations, and chipfracture behavior are systematically analyzed to elucidate the underlying mechanisms of large-diameter reaming in multilayer CFRP/Ti stacks. The experimental findings reveal that the large removal volume strategy generates excessive cutting forces and torque, thereby compromising hole quality. In contrast, the small removal volume strategy sustains machining efficiency while improving hole quality by 85.6 %, thereby effectively fulfilling industrial requirements.

Drilling multidirectional (MD) carbon fiber reinforced polymers (CFRPs) has posed tremendous challenges for the modern manufacturing industry due to their unique properties including anisotropy and heterogeneity. Critical defects such as delamination, burrs and tearing are important issues that raise serious concerns in the manufacturing sectors. To deal with these issues, the current study analyzes the damage formation and surface integrity for MD-CFRP drilling via both numerical and experimental approaches. The key novelty of this research lies in accounting for the interfacial interaction between individual plies and the effect of ply directionality on drilling responses. Based on the developed macroscopic CFRP models, drilling simulations have been conducted along with cutting experiments. The current work offers a comprehensive understanding of how variations in drilling parameters influence the machinability aspects and cutting-induced damages for MD-CFRP laminates. The dynamic delamination formation, which was not fully addressed in traditional experiments, is revealed in the study. The burrs are mainly formed in the exit side of cut CFRP holes and are primarily influenced by the feed rate. Increasing the feed rate significantly exacerbates the tearing damage by 0.18 mm2, while elevating the spindle speed from 1326 to 5305 rpm slightly reduces tearing by 0.03 mm2. To minimize surface damage, low feed rates and moderate spindle speeds are recommended for use from the industrial point of view. The results obtained provide technical guidance and practical implications to realize damage-free drilling of MD-CFRPs for industrial applications.

Machining carbon fiber reinforced polymers (CFRPs) is facing huge challenges due to the generation of crucial damages, posing a fatal impact on structural performance and accuracy. To date, numerous studies have been performed to address the damage issues associated with cutting CFRPs through experimental and numerical ways. However, no review articles are reported so far to summarize the state-of-the-art advances achieved in the numerical modeling of cutting-induced damages for CFRPs. To fill this gap, this paper firstly overviews the fundamental characteristics of cutting-induced damages for CFRPs and then summarizes the potential numerical methods applied for CFRP machining. A particular focus is placed on detailing progress of the constitutive models, failure criteria, definition of tool-chip interaction and frictional behavior for CFRP machining. Moreover, a rigorous literature survey was conducted to report the recent advances in the modeling of orthogonal cutting damages and drilling-induced damages for CFRP composites. The thermo-mechanical effects and parametric effects on the cutting-induced damages as well as the numerical quantification/assessment are illustrated. Eventually, the future perspectives concerning the numerical prediction and estimation of cutting-induced damages for CFRPs are outlined. The paper can benefit both academia and industry to realize damage-free cutting of CFRP composites.

In electrical discharge machining (EDM), the ignition process is the induction process for dielectric breakdown and plasma formation. It is generally believed that using a high ignition voltage is more effective in enhancing the breakdown probability and improving the machining efficiency. However, the discharge gap usually becomes relatively large when using the high ignition voltage. As a result, the contour machining accuracy and surface machining quality may be reduced. This study explores an ignition control method to reduce the probability of breakdown at high voltage without affecting the machining efficiency. A step-rising ignition voltage is proposed to test for ignition step by step from a low voltage. Only if no breakdown occurs during the low voltage stages will the highest voltage be used for ignition. On this basis, the voltage step-rising time is adaptively regulated and an active sweep pulse is generated according to the calculated discharge state index. The experimental results show that compared with ignition using a constant high voltage, the proposed ignition control method is conducive to reducing the tool electrode wear and improving surface quality, while the machining efficiency is still guaranteed.

Nickel-based superalloy (GH4169) is an ideal material for preparing turbine blades. Profile grinding of the fir-tree-shaped turbine blade root can easily cause thermal damage to the workpiece specimen. This study aims to enhance the suppression of alloy thermal damage by regulating the thickness of the oxide film on the cubic boron nitride (CBN) grinding wheel during the electrolytic in-process dressing (ELID)-assisted grinding process. A theoretical model for calculating the thickness of oxide film in ELID-assisted grinding was developed. Finite element simulation was conducted using the electrolytic film-forming process of the grinding wheel. The effects of electrical/nonelectrical parameters on the oxide film characteristics and grinding responses were addressed. The optimal matching scheme of process parameters was established. The results showed that the film layer of the grinding wheel at the blade root cam is more seriously damaged, and the workpiece surface is rougher. Further optimization of the electrode is demanded to achieve different dressing effects at various positions of the grinding wheel based on the workpiece profile. By reducing the interelectrode gap (he), increasing the power supply voltage (Eo), and controlling the electrolysis time (Δt) at 10–15 min, the preferred film-forming efficiency and grinding quality can be achieved. By increasing the grinding wheel speed (Vs) or decreasing the workpiece feed rate (Vf) and grinding depth (ap), the grinding thermal damage can be suppressed. A larger value of Vf or ap can be selected to acquire a compromise between grinding quality and film-forming efficiency after increasing the value of Vs. The optimal combination of electrical and nonelectrical parameters during this test is Eo = 120 V, Δt = 15 min, he = 0.1 mm, Vf = 50 mm min−1, Vs = 30 m s−1, and ap = 0.4 mm.

Understanding the microscopic mechanisms of fiber fracture and removal plays a vital role in optimizing the cutting process and tool wear progression of carbon fiber reinforced polymers (CFRPs). Cutting edge radius (CER) is a critical parameter determining the surface formation of CFRPs as chip removal takes place by the action of cutting edge. In this study, micro-mechanical finite element (FE) models based on the maximum stress criteria were developed to reveal the influences of CER on fiber removal mechanisms governing the orthogonal cutting of UD-CFRPs. The results show that the CER significantly impacts both the transition of fiber removal modes and subsurface damage formation in CFRP cutting. At the 0 degrees fiber orientation, increasing the CER tends to intensify the compression-induced fracture for fiber layers interacting with the tool. While for 45 degrees and 90 degrees fiber orientations, the key fiber separation mode changes from shear-induced fracture to bending-induced fracture as the CER rises. For the 135 degrees fiber orientation, chip removal faces the greatest difficulty, with significant compressing and squeezing effects occurring, leading to poor fiber breakage and severe subsurface damage. Moreover, a smaller CER benefits the reduction of subsurface damage but increases the risk of edge chipping due to higher stresses concentrating at the cutting edge.

Aviation part manufacturing has the features of high processing accuracy, high added value, high customization, long processing cycle, and large material removal, which leads to complex carbon emission characteristics and high-carbon emission intensity throughout the entire manufacturing process. With the increased awareness of the “dual carbon” strategy, green and low-carbon development has become a necessary route for the aviation manufacturing industry. To this end, this paper focuses on the entire manufacturing process of aviation components and defines the carbon emission boundaries of the entire aviation manufacturing operation. The carbon emission characteristics of each process in the entire aviation part manufacturing are analyzed. On this basis, combining the advantages of the improved value stream diagram, the carbon emission modeling and evaluation method for the entire process of aerospace parts manufacturing based on the bill-of-carbon is proposed, so as to achieve the carbon emission fine characterization and carbon efficiency comprehensive evaluation. Finally, the feasibility and effectiveness of the proposed method are verified by the entire manufacturing process of longitudinal skeleton. This paper can provide methodological support for the refined modeling of carbon emissions and carbon efficiency evaluation of large aviation parts, and lay a theoretical foundation for energy saving and carbon reduction in future aviation part manufacturing.

Aluminium/carbon fibre reinforced polymer (Al/CFRP) composite stacks combine the high strength-to-weight ratio of the CFRP with the ductility and impact resistance of aluminium. Due to their excellent mechanical properties, Al/CFRP stacks are becoming increasingly popular in major industrial fields such as aerospace and automotive. However, mechanical machining of these materials, particularly at the interlayer regions, presents significant challenges, notably the formation of interlayer burrs. To address this issue, we introduce an innovative hole-making technology designed to minimise machining-induced interlayer burr formation. The novel technology integrates helical and spiral interpolation strategies to reduce axial force at the interlayer interfaces. We validated the efficiency of the novel technology through a series of machining experiments, employing a Central Composite Inscribed (CCI) experimental design. The experiments were performed on a three-axis CNC milling centre, with burr measurements obtained using a Keyence VR-5000 3D profilometer. Maximum burr heights were recorded along the hole contours at one-degree intervals. Our findings demonstrate a significant reduction (28 %) in interlayer burr formation in unidirectional carbon fibre-reinforced polymer (UD-CFRP) plates when utilising the proposed technique. These results suggest that our developed method is promising to improve machining quality in Al/CFRP stacks, meriting further investigation and development.

The objective of this research work is to machine micro-holes in Ti-6Al-4V alloy using conventional electric discharge machining process and to optimize its machining parameters to achieve maximum material removal rate and minimum electrode wear rate. The process parameters that have been selected for this study were input current (Ip), pulse-on time (Ton) and pulse-off time (Toff). The experiments were carried out based on Box-Behnken L15 design. Using the regression method, mathematical models were developed for output responses (material removal rate and electrode wear rate) and their significance in enhancing machining processes was analysed using surface plots. The input parameters achieving maximum material removal rate was found to be 4 A of input current (Ip), 5.2 µs of pulse-on time (Ton) and 14.4 µs of pulse-off time (Toff), and for achieving minimum electrode wear rate, it was found to be 1 A of input current (Ip), 2 µs of pulse-on time (Ton) and 6.4 µs of pulse-off time (Toff). Further, the multivariate optimization technique, grey relational analysis, was employed to determine the optimal combination of process parameters to maximize material removal rate while minimizing electrode wear rate. The optimum process parameters identified were an input current (Ip) of 1 A, a pulse-on time (Ton) of 8 µs and a pulse-off time (Toff) of 6.4 µs. Experimental results confirmed that these conditions yielded an optimal material removal rate of 0.008 mm3/min and an electrode wear rate of 0.00055 mm3/min. These results confirmed that the optimal values fall within the range of maximum and minimum outputs for material removal rate and electrode wear rate.

The global drive towards net-zero has accelerated the adoption of carbon fibre reinforced polymers (CFRP) for lightweight structures in various sectors such as aerospace, automotive, energy and biomedical. Mechanical machining of CFRP is often necessary to meet dimensional or assembly-related requirements. However, significant challenges including surface defects (delamination, burr, surface roughness), rapid tool wear and material transition issues in drilling CFRP/metal stack, underscore the need for effective, automated process prediction / optimization for improved machining performance. Conventional physics-based models often fall short due to their reliance on extensive computational resources and inability to capture CFRP’s complex machining dynamics arising from thermo-mechanical load coupling and process uncertainties. To address these limitations, recent advancements in artificial intelligence (AI) offer promising, data-driven solutions that reduce reliance on domain-specific knowledge while delivering fast, accurate predictions by uncovering patterns within dataset. This provides a promising solution towards intelligent CFRP machining process with improved quality and efficiency. To date, there is a lack of comprehensive, up-to-date review of data-driven methods in CFRP machining process prediction/optimization. This review fills this gap and provides a critical analysis of data-driven methods in four key application settings: (i) machining process characteristics and surface quality/defects prediction; (ii) tool wear prediction; (iii) material transition recognition in CFRP/metal stacks machining; (iv) vision-based surface defects recognition. By presenting a state-of-the-art overview of advances, challenges and future research directions, this review highlights the transformative potential of data-driven methods in advancing intelligent CFRP machining within the manufacturing value chain.

The global drive towards net-zero has accelerated the adoption of carbon fibre reinforced polymers (CFRP) for lightweight structures in various sectors such as aerospace, automotive, energy and biomedical. Mechanical machining of CFRP is often necessary to meet dimensional or assembly-related requirements. However, significant challenges including surface defects (delamination, burr, surface roughness), rapid tool wear and material transition issues in drilling CFRP/metal stack, underscore the need for effective, automated process prediction/optimization for improved machining performance. Conventional physics-based models often fall short due to their reliance on extensive computational resources and inability to capture CFRP’s complex machining dynamics arising from thermo-mechanical load coupling and process uncertainties. To address these limitations, recent advancements in artificial intelligence (AI) offer promising, data-driven solutions that reduce reliance on domain-specific knowledge while delivering fast, accurate predictions by uncovering patterns within dataset. This provides a promising solution towards intelligent CFRP machining process with improved quality and efficiency. To date, there is a lack of comprehensive, up-to-date review of data-driven methods in CFRP machining process prediction/optimization. This review fills this gap and provides a critical analysis of data-driven methods in four key application settings: (i) machining process characteristics and surface quality/defects prediction; (ii) tool wear prediction; (iii) material transition recognition in CFRP/metal stacks machining; (iv) vision-based surface defects recognition. By presenting a state-of-the-art overview of advances, challenges and future research directions, this review highlights the transformative potential of data-driven methods in advancing intelligent CFRP machining within the manufacturing value chain.

Pool boiling performance enhancement has attracted considerable interest on high power electronic cooling. In this paper, we introduce a self-induced jet impingement device for practical boiling enhancement, achieved by integrating the guidance tube with an orifice plate. With R1336mzz(Z) as the working fluid, we conduct visualization and parametric investigations on the pool boiling performance, considering the varying characteristics of this device. Visualization snapshots confirm the liquid-vapor separation and indicate that the two-phase flow pattern in the guidance tube eventually stabilizes as a churn-annular flow. Our findings suggest that self-induced liquid jet impingement has a minimal effect on the nucleate boiling heat transfer coefficient (hNB) under a certain heat flux, around 75 % CHF of the standard pool boiling, as the single-phase heat transfer is weakened due to the low thermal conductivity of R1336mzz(Z). As the heat flux intensifies, we observe substantial enhancements in both the Critical Heat Flux (CHF) and the Maximum Nucleate Boiling Heat transfer coefficient (hMNB) resulted from the delayed onset of boiling crisis, owing to the additional liquid supply and the promotion on vapor exhausting. The parametric studies reveal that the flow rate of the liquid jet, amplified by either extending the length or the inner diameter of the guidance tube, or by increasing the number of jet holes, positively impacts the boiling performance. However, these improvements show diminishing returns. Our study shows enhancements in CHF and hMNB of up to 69.5 % and 36.7 %, respectively, compared to the standard pool boiling.

The main objective of this investigation is to study the effect of post weld heat treatments (PWHTs) on tensile properties, hardness, and microstructure of pulsed CMT-MIG (cold metal transfer arc – metal inert gas) welded AA20214-T6 aluminium alloy joints. The welded joints were subjected to PWHT of artificial aging (AA), solution annealing treatment (ST) and ST + aging (STA). The tensile properties and microhardness of joints were evaluated. The microstructure of joints was studied using optical (OM) and transmission electron microscope (TEM). The fractured surface of tensile specimens was analyzed using scanning electron microscope (SEM). Results showed that the tensile properties and hardness of as welded and PWHT joints are inferior compared to BM. This mainly refers to the microstructural heterogeneity in different regions of joints and softening of heat affected zone (HAZ) induced by the weld thermal cycle. The PWHTs of AA and ST did not show significant effect on tensile strength and hardness of AW joints. However, the slight reduction in elongation was observed in AA and ST joints. The STA joints showed higher joint efficiency of 71.6%, than other joints by compromising on the elongation. This refers to the greater precipitation of hardening precipitates in STA joints compared to AA and ST joints. It exhibited the higher tensile and yield strength of 326 MPa and 266 MPa and the lowest elongation of 3.8%. The STA joints showed 28.35%, 38.28% and 57.77% reduction in tensile strength, yield strength and elongation compared to base metal (BM) respectively. All the tensile specimens of joints failed in HAZ owing to the lower hardness. This refers to dissolution of precipitates in HAZ. However, the HAZ softening is less severe in STA joints than AW, AA, and ST joints.

Microchannel flow boiling is one of the most effective solutions to the problem of heat dissipation caused by high power electronic devices. However, inherent drawbacks such as low critical heat flux due to dry-out of the liquid film near the channel exit, relatively high two-phase flow pressure drop, severe temperature nonuniformity and boiling instability at high heat flux still prevent widespread commercial application. In this study, based on the idea of uniform vapor quality along the flow direction, a copper Counter-Flow Interconnected Microchannel (CFIM) was proposed to address the main issues currently faced by two-phase microchannel heat sink. A comprehensive comparative study of CFIM, Co-Current Microchannel (CCM) and Counter-Flow Microchannel (CFM) was carried out from the aspects of boiling stability, boiling heat transfer characteristics and temperature uniformity. Three slots of 0.2 mm, 0.5 mm and 0.8 mm in width, denoted as IM0.2, IM0.5 and IM0.8, respectively, are considered. Experiments are conducted at mass fluxes of 291-618 kg/m(2)& sdot;s, saturation temperature of 40 degrees C and effective heat fluxes of 3-293 W/cm(2), using the dielectric fluid R1233zd(E) as the working fluid. The results show that the CHF and average two-phase heat transfer coefficient (HTC) of CFIM are increased by 40.6 similar to 100.5 % and 70.4-83.6 %, respectively, while the two-phase pressure drop is decreased by 17-32.6 % compared to CCM. The design of the counter-flow interconnected structure can manipulate the void fraction and two-phase flow pattern, resulting in a near uniform void fraction and flow pattern. The structure of these connecting slots promotes nucleate boiling and fluid mixing of neighboring channels. More importantly, the flow boiling instability and temperature non-uniformity in CFIM are well suppressed. In addition, IM0.2 has higher heat dissipation than IM0.5 and IM0.8 due to enhanced bubble nucleation, reducing superheat requirements and periodic rewetting to the center of the channel. The results of this research reveal that utilizing a microchannel heat sink with a counter-flow interconnected configuration can effectively improve heat transfer performance during flow boiling. Furthermore, it helps to mitigate issues such as flow boiling instability and temperature nonuniformity.

Enhancing pool boiling performance is crucial for cooling high-power electronics. Inspired by the concept of liquid-vapor separation, we have developed a self-induced jet impingement device to enhance pool boiling, achieving notable results when combined with microporous copper surfaces in subsequent studies. This paper focuses on using sandblasted pin-fin surfaces as heating surfaces and explores their pool boiling performance under varied pin-fin and self-induced jet device parameters. Findings indicate that the self-induced jet device effectively mitigates the obstruction caused by nucleating bubbles to liquid replenishment, leading to improved qCHF and hNB@CHF performance compared to standard conditions. The impact of pin-fin sidewall characteristics, determined by the manufacturing process and parameters, is significant, particularly in enhancing boiling heat transfer performance for dielectric liquid cooling processes. Pool boiling performance is negatively affected by too short or too tall pin-fin heights, irrespective of the self-induced jet presence. Simple strategies like increasing guidance tube length or jet holes number are inadequate for enhancing qCHF. However, increasing the number of jet holes with strategically placing it between pin-fins could still improve boiling performance. This study demonstrates qCHF enhancements of up to 145.8%, achieving a qCHF of 61.2 W/cm2, which noticeably surpasses standard pool boiling conditions.

Creep-feed profile grinding of superalloy fir tree-shaped turbine bladeroot (FTTB) is highly susceptible to thermal damage. The paper aims to provide technical guidance for solving the aforementioned engineering issues. The formation mechanisms of thermal damages in superalloy profile grinding were revealed by establishing a finite element model of abrasive scratching and grinding temperature field. Based on the grinding tests, the effects of thermal damages on the surface integrity during the superalloy grinding were rigorously addressed. The results indicate that superalloy is easy to make the heat flux in the machining area exceed the critical value due to the material properties, the coolant lose the heat transfer ability, and the instantaneous high temperature trigger thermal damages. Convex teeth of bladeroot are more likely to initiate thermal damages, while the CBN abrasives can effectively suppress grinding thermal damages due to their high hardness and superior thermal conductivity. The procedure parameters and surface integrity of superalloy grinding are determined by adjusting the maximum undeformed chip thickness. The thermal damages of grinding superalloys can easily cause oxidation discoloration, fish scale like coating texture, microcracks, broken pits, residual tensile stress, hardness reduction, metallurgical organization transformation, significant roughness and high profile size errors on the surface of the specimen.

In this work, electrochemical deposition techniques (galvanostatic and potentiostatic) were used to obtain coatings of a new composite polymer, 3-methylpyrrole—sodium dodecyl sulfate/poly 2-methythiophene (P3MPY-SDS/P2MT), on cobalt-based alloy samples for anti-corrosion safety. The use of sodium dodecyl sulfate as a dopant ion in electrosynthesis can have a relevant effect on the anticorrosive property of the composite polymer layer by blocking the entry of corrosive ions. The cobalt alloy specimen had an important impact on the electrochemical performance of the composite coating and this together with the presence of the polymeric layer was achieved by simultaneously constitution of a complex oxides film and polymeric layers. The polymeric coatings were analyzed using scanning electron microscopy (SEM), Fourier transform infrared (FT-IR) spectroscopy, and cyclic voltammetry (CV) methods. The corrosion protection of the P3MPY-SDS/P2MT-covered cobalt-based alloy was explored using electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization procedures in a 1 M HCl solution. The corrosion speed of the P3MPY-SDS/P2MT-covered cobalt-based alloy was observed to be ~10 times less than an uncovered specimen, and the effectiveness of the composite layers of this coating is greater than 91%. This superior efficaciousness was obtained by the electropolymerization of P3MPY-SDS/P2MT at current densities of 1 mA/cm2 and 0.5 mA/cm2, applied potentials of 0.9 V and 1.0 V, and a molar ratio of 5:1. Corrosion test results indicate that the P3MPY-SDS/P2MT coatings provide a good result: protection against the corrosion of a cobalt-based alloy in aggressive solutions.

The exceptionally high hardness and active plaque adhesion ability of 3Y-TZP ceramics often cause lots of oral diseases. This work intends to enhance the service performance of such ceramic dentures in human oral cavity by surface texturing technique. Efforts have been made to tackle the surface texture formation mechanism under 2D-UVAM process and establish the connection between the key surface properties and texture morphologies. The impacts of cutting parameters, vibration parameters, and tool geometry parameters on texture morphologies were rigorously studied. The coupling effect of wettability, antibacterial activity, and frictional performance of textured ceramic surfaces was also investigated. The acquired results indicate that the fish-scale texture with high density helps to enhance the hydrophobicity of the zirconia ceramics, while the wavy texture with low density promotes the ceramic material towards a hydrophilic direction. The antibacterial activity is highly related to wettability. The larger contact angle generally means the more pronounced inhibition effect on plaque adhesion. The wear of natural teeth decreases significantly after introducing textures on the ceramic surfaces, but the wear amount is not sensitive to wettability. Therefore, the hydrophobic surface can simultaneously improve the antibacterial characteristics of 3Y-TZP ceramics and its tribological compatibility with the natural teeth.