ABSTRACT This study examines the influence of ultrasonic-assisted turning (UAT) on the surface finish of hardened Mo40 steel under various cutting speeds, feed rates, and ultrasonic excitation voltages (Vg) at 21 kHz. Compared to conventional turning (CT), UAT improves surface quality most effectively at lower cutting speeds and higher ultrasonic amplitudes. Increasing Vg enhances vibration-induced surface micro-disruptions, producing finer textures and reduced roughness. These benefits are maximized at low-to-moderate cutting speeds and feed rates. Above a critical cutting speed, UAT efficiency declines due to continuous tool contact, causing a slight roughness increase. Optimization identifies an ideal combination of feedrate (0.07 mm/rev), ultrasonic voltage (130 V), and cuttingspeed (27 m/min) for minimal surface roughness. Findings highlight ultrasonic excitation voltages (vibration amplitude) as a key factor in achieving superior surface finish and demonstrate UAT’s potential to enhance machining of hardened steels, offering improved precision and component longevity for industrial applications.

The automotive, aerospace, biomedical, and other engineering sectors make substantial use of Ti6Al4V titanium alloy, known for its high strength-to-weight ratio, corrosion resistance, and biocompatibility, but it often suffers from poor tribological performance and low surface hardness. To increase durability, a variety of surface modification techniques have been investigated, including chemical etching, shot peening, thermal oxidation, laser surface texturing, and physical vapor deposition. However, these methods frequently entail high thermal input and mechanical stress with limited control over surface chemistry. Electrochemical methods, on the other hand, allow uniform and precise alteration of surface morphology without thermal or mechanical damage. Among these, anodization and plasma electrolytic oxidation (PEO) facilitate hardening and stress-free surfaces but suffer from passive film formation, porosity and micro-cracks, while electrochemical polishing (ECP) yields much better surface finish but at high energy cost and causes passive film formation. In this review, electrochemical machining (ECM), typically viewed as a subtractive method for material removal, is reevaluated as a process for both material removal and functional surface tailoring. Despite its application for removing material, ECM promotes valence-controlled dissolution that favours the formation of lower oxidation states of titanium. It also inhibits the formation of passive films and enables the formation of atomically smooth surfaces. The present study provides a novel theoretical framework for customizing Ti6Al4V surfaces with improved functional and morpho­logical properties by integrating ECM with anodization, PEO and ECP within the broader paradigm of electrochemical surface engineering.

Balancing surface finish and ablation depth in direct laser turning of RB-SiC based on combined IPSO-SVR models with MOAHA-TOPSIS method

ABSTRACT Volumetric additive manufacturing (VAM) enables one-step, layer-free fabrication of 3D parts by spatially controlling energy–matter interactions within a photosensitive resin. While VAM is faster than conventional layer-based printing and well suited for complex geometries, wider adoption is limited by coupling between exothermic curing and non-uniform light fields. This interaction degrades surface finish and dimensional accuracy, reducing mechanical and functional performance. Herein, we propose a low-temperature assisted VAM (L-VAM) strategy that tunes resin viscosity via precise temperature–reaction coupling. By stabilizing material flow and mitigating uneven thermal gradients and irradiance disparities, L-VAM suppresses defect formation associated with spatially varying fluidity and heating. Experiments show that an optimized L-VAM process significantly improves dimensional stability and surface quality, delivering a 65.3% reduction in surface roughness compared with conventional VAM. These improvements establish the proposed L-VAM strategy as particularly suitable for high-precision applications including micro-optics and soft robotics.

This study characterizes the mechanical behavior of Ti‐6Al‐4V lattice structures manufactured using laser powder bed fusion (PBF‐LB/M) for application in endoprostheses. Additive manufacturing enables creating customized orthopedic implants with complex geometries that combine mechanical stability with biological integration. The choice of biocompatible Ti‐6Al‐4V, together with the incorporation of lattice structures, offers improved mechanical performance, corrosion resistance, and bone ingrowth. A critical step toward the clinical adoption of such additively manufactured lattice structures is their thorough mechanical characterization, the central focus of this work. To this end, three test methods are employed to assess macroscopic mechanical response and damage tolerance: uniaxial compression, fourpoint bending and crack propagation tests. The results show that the mechanical properties depend on the lattice topology and surface finish. In particular, TPMS‐based architectures (Triply Periodic Minimal Surfaces) exhibit superior fatigue crack propagation behavior, which is attributed to a more homogeneous stress distribution. In static testing, the SplitP TPMS (SPP) and Honeycomb (HCG) structures achieve the best balance of high stiffness (up to 27 GPa) and compressive strength (up to 249 MPa). These experimentally validated data form a crucial basis for subsequent artificial intelligence (AI)‐based structural optimization to maximize the long‐term mechanical reliability of implants under physiological loads.

Reliable tool condition monitoring (TCM) plays a critical role in precision machining, where progressive wear can lead to dimensional inaccuracies, degraded surface finish, and unplanned downtime. Despite advances in data-driven diagnostics, most machine-learning solutions remain constrained by their reliance on extensive labelled datasets, which poses a major barrier to industrial adoption. To address this limitation, this work introduces a Self-Supervised Masked-Feature Pretraining (SSL-MFP) framework that learns latent vibration representations by reconstructing partially masked time-frequency features, thereby eliminating the need for class labels during the initial learning stage. The pretrained encoder is subsequently fine-tuned using only a small subset of the labelled dataset for downstream drill-wear classification, markedly reducing annotation demands. The framework is evaluated on a fused vibration-feature dataset and benchmarked against established supervised baselines spanning machine-learning and deep-learning architectures. Results indicate that the proposed approach achieves classification accuracy comparable to that of fully supervised models while utilizing significantly fewer labelled samples, demonstrating effective generalization under limited annotation conditions. Furthermore, the learned feature manifold exhibits distinct class separability, evidencing the representational strength of the self-supervised encoder. Overall, the SSL-MFP paradigm provides a data-efficient foundation for TCM, enabling industrial deployment where labelling costs and adaptation are critical challenges.

Abstract Wire-arc additive manufacturing (WAAM) is a state-of-the-art near net shape manufacturing technology for manufacturing structures with tailored mechanical properties. However, the process typically requires minor post-processing (e.g., machining) to achieve the desired surface finish and dimensional accuracy. This study investigates the mechanical properties and the concomitant microstructural evolution in a WAAM bimetallic comprising of a low alloy carbon steel (P22) and Inconel 625 nickel alloy (IN625) using gas metal arc welding (GMAW). Microstructural examination revealed distinct microstructural features, including bainite-ferrite morphology in P22 steel and a dendritic γ-austenite matrix in IN625 with intermetallic Laves phase precipitates. The interface exhibited a defect-free metallurgical bond, characterised by martensitic laths within the P22 region, primarily due to rapid cooling, and columnar grains in the IN625 region due to directional solidification. Tensile and Charpy impact tests revealed that IN625 exhibited superior mechanical properties, whereas the bimetallic component displayed moderate strength with reduced ductility. In these tests, fractures appeared to consistently occur on the P22 side, due to the presence of Mn-rich inclusions. Crystallographic texture analysis showed near random texture for the P22 steel, governed by recrystallisation and phase transformation dynamics. In contrast, the texture of the IN625 deposit cannot be concluded due to the small number of directionally grown grains during WAAM.

Surface finish plays a critical role in the tribological performance of additively manufactured engineering components. In exploring part characteristics in laser powder-bed fusion (L-PBF), this study investigates the effect of contouring strategies on the upskin surface of inclined specimens (30°, 45°, and 60°) made with L-PBF, using post- and pre-contouring strategies with various levels of process parameters. The surface data of fabricated inclined specimens were acquired by white-light interferometry, followed by a quantitative analysis using surface images. The results show that post-contouring leads to better surface finishes, with the lowest Sa of 8.68 µm attained at the highest laser power (195 W) and the slowest scan speed (500 mm/s) on 30°-inclined specimens, likely due to increased remelting and less step-edges. In contrast, pre-contouring produces distinct surface textures on the upskin of L-PBF specimens, resulting in a rougher surface morphology, with a maximum Sa of 33.39 µm also from 30°-inclined specimens at the lowest power (100 W) and the highest speed (2000 mm/s), suggesting an insufficient remelting of surface defects. In comparative analysis, in general, post-contouring yields smoother upskin surfaces, with a 17%–30% reduction in Sa, than those from equivalent pre-contouring conditions, highlighting the potential of scan sequences for optimizing L-PBF to improve the surface finish of inclined structures.

Self-Compacting Concrete (SCC) has become an important advancement in concrete technology due to its ability to flow under its own weight, fill formwork completely, and pass through congested reinforcement without external vibration. These characteristics improve construction efficiency, reduce labor and noise, and enhance surface finish and structural reliability (Okamura & Ouchi, 2003; EFNARC, 2005). As a result, SCC is increasingly used in complex structural applications. However, the production of SCC often requires high cement content and carefully controlled aggregate grading, which can increase cost and environmental impact. In recent years, growing concerns over climate change and resource depletion have driven research toward more sustainable concrete materials. One widely adopted approach is the use of supplementary cementitious materials (SCMs) to partially replace ordinary Portland cement. Ground Granulated Blast Furnace Slag (GBFS), a by-product of the steel industry, has been extensively studied due to its ability to reduce carbon emissions while improving long-term mechanical performance and durability of concrete (Shi et al., 2015; Thomas, 2018). Studies conducted between 2020 and 2025 have confirmed that GBFS can enhance later-age compressive strength in SCC by refining pore structure and contributing to continued hydration, although early-age strength may be slightly reduced depending on replacement level (Singh et al., 2021; Li & Huang, 2023). In addition to cement replacement, the selection and proportioning of aggregates play a critical role in determining SCC performance. Aggregate characteristics such as shape, surface texture, and grading strongly influence fresh properties, particularly flowability, passing ability, and segregation resistance (Neville, 2011). Recent research has shown that the use of alternative or processed aggregates, including Crushed Stone Aggregate (CSA) and Coarse Processed Aggregate (CPA), can significantly affect SCC rheology and strength development. Angular and rough-textured aggregates tend to increase internal friction, thereby reducing workability unless compensated by mix design adjustments or chemical admixtures (Mohammadhosseini et al., 2021; Wang et al., 2022). Workability has consistently been identified as one of the most sensitive properties of SCC incorporating sustainable materials. Several studies conducted in the last five years report that increasing the proportion of SCMs or alternative aggregates can reduce slump flow and stability if not properly optimized (Abbas et al., 2023; Safiuddin et al., 2021). Conversely, appropriate use of GBFS has been shown to improve the viscosity and cohesiveness of SCC, contributing to stable flow behavior when combined with suitable aggregate grading (Zhang et al., 2022).

Metal mesh-reinforced thermoplastic composites have emerged as promising candidates for lightweight, energy-absorbing structures in aerospace applications. However, their mechanical performance is highly sensitive to fabrication parameters such as winding angle, layer sequence, and forming pressure. In this study, a hybrid tube structure composed of GF/PP prepreg and stainless-steel mesh was fabricated using a manual winding process, aiming to optimize the structural design and processing conditions. A custom-built winding platform was used to ensure stable operation, and the effects of lay-up configuration and compaction pressure were investigated. The [45°/-45°/metal mesh/-45°/45°] lay-up with 40 N pressure offered superior surface finish and mechanical balance through improved interfacial bonding. Mechanical tests, including tensile, compressive, and shear experiments were conducted according to ASTM standards. The GF/PP composite exhibited high tensile strength along the fiber direction and stable shear resistance, while the metal mesh demonstrated elastic–plastic behavior under uniaxial loading. The results confirm the feasibility of the proposed process and lay-up strategy, providing a basis for structural design and simulation of high-performance hybrid components.

Background: Composite restorations are the standard of care for posterior teeth due to their aesthetic properties and conservative nature. However, the choice between direct and semi-direct techniques can influence clinical longevity and performance. Objectives: This study aimed to compare the clinical performance of two restorative approaches: a direct technique and the semi-direct onlay technique in terms of aesthetic quality, surface finish, wear resistance, marginal integrity, and overall clinical efficiency over a two-year period. Methods: A total of 348 composite restorations were placed in 192 patients. Each restoration was evaluated at four timepoints: baseline (T0), 6 months (T1), 1 year (T2), and 2 years (T3). Clinical performance was assessed using standardised 5-point rating scales across the five dimensions. Repeated-measures ANOVA assessed changes over time, while Wilcoxon signed-rank and Mann-Whitney U tests were used for intra- and inter-group comparisons. Results: Significant time effects were observed across all clinical parameters (p < 0.0001). The direct technique exhibited superior initial results in aesthetics and surface finish at T0 and T1 (p < 0.001), but differences diminished by T3. In contrast, the semi-direct technique demonstrated improved performance in wear resistance and marginal integrity at T2 and T3. Both techniques showed progressive deterioration, particularly in marginal adaptation. Conclusions: The direct technique offers enhanced short-term aesthetics and procedural efficiency, while the semi-direct approach provides superior long-term durability and marginal adaptation.

ABSTRACT In hot strip rolling, even moderate variations in transfer bar (TB) thickness can critically affect the final strip profile and surface quality. This study investigates the influence of roll wear in the last roughing stand (R5) on these inconsistencies by integrating plant measurements with finite element method (FEM) simulation. Work roll profiles were captured at different stages of a rolling campaign using a Pessometer. These profiles were precisely reconstructed using CAD software and incorporated into the FEM based DEFORM-3D simulation environment to reflect worn roll geometries within a thermo-mechanical framework. A comprehensive FEM model was developed to emulate real mill conditions; from slab discharge at the reheating furnace to deformation through the roughing stands and up to the third finishing stand, where the strip's geometric integrity, especially profile is predominantly established. Simulations conducted with varying degrees of R5 roll wear revealed that roll surface degradation induces non-uniform thickness distribution in the TB. These inconsistencies persist into the finishing mill and lead to shape-related defects such as ridge formation. This integrated approach not only helps to visualise the genesis of shape defect but also provides actionable insights into optimal roll maintenance schedules and control interventions to ensure more uniform strip production.

The strong competition and demands of the global market in the manufacturing industry make the use of advanced technologies and the study of more effective and precise working methods increasingly necessary. The automation of computer numerical control (CNC) machine tools has gained great importance in the manufacturing industry, optimizing resources and reducing production errors due to human failure. In the present work, the design and implementation of a three-axis CNC machine for additive and subtractive manufacturing combined in a single machine was carried out. To create an optimal and functional design, it was necessary to establish parameters for the three applications to be performed. The speeds and parameters that influence laser cutting were researched, as well as the variables involved in 3D printing and the technical characteristics necessary to carry out wood carving. All these applications are for a work area of 600 mm x 600 mm with a height of 200 mm in the case of 3D printing and 150 mm in the case of carving. As support, to perform structural simulations, the system was designed in CAD software and then its respective CAE analysis was carried out, where it was verified that the sizes of the created elements withstand the loads produced in the processes carried out. Due to differences in speed and torque parameters, it was necessary to design two gantries where the three aforementioned processes are located, with different motion transmissions that allow the applications to be executed with ideal parameters. For the control of movements and activation of electrical components, the MARLIN firmware was used, which allows the generation of different types of CNC applications from a control board in which all necessary actuators are implemented. For the tests, the ISO 10360-2 2009 standard was used to determine the accuracy and repeatability of the structure; additionally, tests were carried out on geometric figures verifying the error in all processes performed. Finally, conclusions and recommendations have been established. With the design and implementation of this prototype, the aim in machining is to reduce manufacturing times, improve surface finish, and manufacture more complex parts; in academia, to have a prototype for carrying out machining practices; and in the industrial field, to have a machine that is accessible in terms of cost, operation, and maintenance.

Carbon fiber-reinforced poly (ether-ether-ketone) (CF/PEEK) is a widely used composite material in aerospace, automotive, and biomedical applications. However, achieving a high-quality surface finish during machining remains challenging due to its low thermal conductivity and high abrasiveness. This study investigates the thermal effects of using cooled compressed air (CCA at −40°C) and heated compressed air (HCA at 60°C) on surface finish during face milling of PEEK reinforced with 30% short carbon fiber (CF30), compared to dry machining (DRY). A Box-Behnken experimental design was applied with three levels of cutting speed ( v c ), feed per tooth ( f z ), and axial depth of cut ( a p ). Surface profiles and roughness parameters ( R a and R z ) were statistically evaluated using ANOVA, Abbott–Firestone curves (AFC), and probability density functions (PDF). Scanning electron microscopy (SEM) and 3D interferometry were employed to analyze the optimized and best-performing samples. Results indicated that the lowest roughness values were achieved under CCA, while HCA yielded the highest. In both cases, f z was the most significant factor. AFC and PDF analyses confirmed that surfaces machined with CCA exhibit a more homogeneous 2D roughness profile, with less pronounced peaks and valleys. The regression model accurately predicted roughness values under CCA, with an error of approximately 4%, aligning well with experimental results ( R a = 0.307 μm, R z = 2.210 μm) and maintaining a suitable material removal rate (MRR = 1723 mm 3 /min). SEM images revealed that CCA enhances surface finish by increasing composite stiffness, facilitating cutting. 3D roughness profiles confirmed isotropic characteristics for all conditions. After optimization, CCA exhibited the lowest S a (0.371 µm), DRY the lowest S z (12.42 µm), and HCA the roughest surface profile, confirming the trends observed in 2D analysis.

Purpose This paper aims to investigate the interfacial reaction mechanisms and microstructural evolution between In-Ag thermal interface materials (TIMs) and electroless nickel-immersion gold (ENIG) surface finishes during thermocompression bonding and subsequent solid-state aging. Design/methodology/approach Pure In, In-3Ag and In-10Ag foils were bonded to Cu substrates with electroplated Ni/Au or ENIG coatings. Cross-sectional scanning electron microscopy and energy-dispersive X-ray spectroscopy were used to analyze interfacial phases. The effects of Au layer thickness, Ag alloying and long-term annealing at 120°C up to 1000 h were systematically examined. Findings Electroplated Ni/Au finishes with a 0.3-µm-thick Au layers promoted the formation of brittle (Au,Ni)In2 intermetallic compounds (IMCs), whereas ENIG with a 0.05-µm-thick Au layer suppressed AuIn2 formation and favored Ni28In72 growth. Ag addition to In TIMs generated Ag-based IMCs (AgIn2, Ag2In), which partially transformed into Ag3In during aging, with Cu and Ni atoms substituting Ag lattice sites. The combined use of ENIG finishes and Ag alloying effectively reduced brittle AuIn2IMC formation and improved interfacial stability. Originality/value This work provides insights into interfacial phase evolution in In-Ag/ENIG systems and identifies practical strategies – Au layer thickness control and Ag alloying – for enhancing the reliability of metallic TIMs. The findings demonstrate the potential of ENIG/In-Ag joints for next-generation high-performance electronic packaging.

Aims: This in vitro study aimed to evaluate the effects of different surface finishing procedures-mechanical polishing, glazing, and polishing followed by glazing-on the color stability, surface roughness, and gloss of three CAD/CAM ceramic materials [feldspathic glass ceramic (GC), lithium disilicate (LDS), and zirconia-reinforced lithium silicate (ZLS)] after aging in a coffee solution. Methods: A total of 108 rectangular ceramic specimens (n=36 per material) were prepared in accordance with ISO 6872. Each material was divided into three subgroups based on the surface finishing procedure: mechanical polishing, glazing, and polishing+glazing. Baseline measurements of surface roughness (Ra), gloss (GU), and color (CIEDE2000, ΔE₀₀) were recorded. Specimens were aged in a coffee solution at 37 °C, and measurements were repeated at 1 week, 2 weeks, 1 month, and 2 months. At the end of the 2-month period, all specimens were re-polished and final measurements were obtained. Data were analyzed to determine material-, time-, and procedure-dependent differences. Results: Surface finishing protocols significantly affected all evaluated parameters (p &lt; 0.05). Mechanical polishing produced the lowest Ra values (0.19±0.05 µm), while glazing alone resulted in the highest Ra after aging. The greatest increase in Ra was observed in zirconia-reinforced lithium silicate, whereas LDS maintained the lowest values throughout the study. The polishing+glazing protocol exhibited the highest GU (76.24±9.19 GU). LDS ceramic demonstrated the best GU retention, while ZLS showed the most pronounced loss over time. Both material type and finishing method significantly influenced ΔE₀₀ (p

Multi-criteria decision making approach for selecting the best Ti alloy turning parameters by analysing the influence of cutting force on surface finish under different conditions

Achieving near-atomic-level surface finish on GCr15 bearing steel via CMP: mechanisms and process optimization

ABSTRACT This study investigated the agronomic performance and root characteristics of perennial ryegrass and mixed perennial ryegrass–plantain swards under intensive rotational grazing by dairy cows in Northern Ireland over two full grazing seasons (2023–2024). Key objectives were to evaluate herbage yield, growth dynamics, utilisation, botanical composition, forage quality and root morphology. Total seasonal yield PRG and PRG‐PL were 11,683 and 11,766 kg DM ha −1 , respectively. The PRG‐PL swards exhibited greater herbage utilisation (80.5% vs. 76.7%). Herbage quality analyses showed mixed perennial ryegrass–plantain swards had higher ash ( p &lt; 0.001) and acid detergent fibre ( p &lt; 0.01), but lower neutral detergent fibre ( p &lt; 0.001), water‐soluble carbohydrates ( p &lt; 0.001), digestibility ( p &lt; 0.001) and gross energy ( p &lt; 0.001) compared to perennial ryegrass. Botanical composition remained consistent across years, with mixed perennial ryegrass–plantain swards averaging ~29% plantain. Root assessments revealed perennial ryegrass swards had significantly greater fine root development ( p &lt; 0.001), biomass ( p &lt; 0.001) and surface area ( p &lt; 0.001) to 30 cm soil depth, whilst mixed perennial ryegrass–plantain sward roots were fewer in number but exhibited slightly thicker diameters in deeper layers. Plate metre calibration showed no significant difference ( p &gt; 0.05) between sward types, validating the use of a common equation. Notably, mixed perennial ryegrass–plantain swards ( p &lt; 0.05 ) showed increased growth during periods of low rainfall, suggesting enhanced drought resilience. These findings indicate that incorporating plantain into perennial ryegrass swards can enhance utilisation efficiency and potentially improve resilience under variable climatic conditions without compromising annual productivity. This research provides robust, year‐on‐year data supporting the agronomic viability of moderate plantain inclusion in temperate grazing systems.

This research explores how surface grinding parameters affect the surface roughness of Aluminum 7075 thin plates, a material that is commonly utilized in the marine sector. A full factorial design of experiments with three factors at three levels was used to assess the impact of table speed, feed, and grinding depth on root mean square roughness (Rq) and average roughness (Ra). Measurements of surface roughness were conducted at three linear locations (10 mm, 25 mm, and 40 mm) along the plate to ensure both accuracy and consistency. Among the variables analyzed, the feed rate and grinding depth were identified as the most significant factors, exhibiting the highest standardized effect of 9.67 on both root mean square roughness and average roughness. This pronounced relationship suggests that higher feed and greater grinding depths enhance material removal and interaction between the tool and workpiece, resulting in increased roughness values. The table speed also had a notable impact on surface finish, with standardized effects of 6.84 and 5.78 for Rq and Ra, respectively; a rise in table speed was associated with more roughness, likely due to reduced material contact. The interaction between feed and grinding depth showed statistical significance, demonstrating standardized effects of 4.89 and 3.61 on Rq and Ra, respectively, reinforcing their combined effect on the formation of surface texture. The optimal grinding parameters were determined to be high table speed (50 spm), high feed (5 mm) and high grinding depth (1.0 mm).