This study presents a novel numerical framework that elucidates the critical, yet previously underexplored, role of Marangoni vortex dynamics in determining the final surface quality during the laser polishing of Ti6Al4V (TC4). TC4 titanium alloy is widely used in aerospace, biomedicine, and other high-precision applications due to its excellent specific strength, corrosion resistance, and biocompatibility. However, its surface quality directly affects the fatigue life and service performance of parts, and traditional polishing methods suffer from low efficiency and high pollution. As a non-contact, controllable surface treatment technology, nanosecond laser polishing has demonstrated unique advantages in balancing processing efficiency and surface quality. This study systematically discussed the influence of key process parameters (spot overlap rate, laser power, and scanning times) on the nanosecond laser polishing of TC4 titanium alloy. It revealed the internal physical mechanism by analyzing the temperature and velocity fields and vortex dynamics during molten-pool evolution. It is found that the polishing effect is determined by the process parameters, which adjust the thermal–fluid coupling physical field (temperature distribution, melt flow, and vortex structure) in the molten pool. There is an optimal combination of parameters (spot overlap rate of 79%, laser power of 0.8 W, scanning speed of 5 m/min, scanning 3 times) that can place the molten pool in an optimal dynamic balance state and achieve effective flatness. The experimental results show that, under this parameter, the surface roughness of the specimen with an initial roughness of 1.223 μm is reduced by about 32%. The research further clarified the mechanism by which the initial roughness of the base metal influences the molten pool: the greater the initial roughness, the more pronounced the “peak shaving and valley filling” effect. Under the same parameters, the improvement rate of the specimen with the initial roughness of 1.623 μm could reach about 40%. This study not only establishes the optimized process window but also reveals the essential relationship between “process parameters–bath behavior–surface quality” from the level of the physical field of the molten pool. The findings provide a practical guideline for parameter optimization, directly applicable to the high-precision laser finishing of critical titanium components in the aerospace and biomedical industries.
The growing demand for sustainable materials has driven interest in natural fiber-reinforced composites as eco-friendly alternatives to synthetic materials. This research investigates the fabrication and mechanical performance of hemp and sisal fiber-reinforced composites, with a focus on improving fiber–matrix bonding through alkali and fungal treatments. Experimental results show that fungal treatment significantly improves tensile and flexural strength, while hardness slightly decreases. Water absorption tests revealed moderate reductions in hydrophilicity compared to untreated samples, although absolute water uptake remains higher than conventional glass/epoxy composites. Microscopy analysis further confirmed enhanced fiber adhesion and structural integrity in treated specimens. These findings suggest that hybrid composites reinforced with hemp and sisal, particularly with fungal treatment, hold promise for low-to-medium load sustainable applications in the automotive interiors, packaging, and construction industries, where moderate mechanical performance and partial biodegradability are acceptable. This research contributes to the advancement of bio-based composite materials while acknowledging current limitations in long-term durability and complete biodegradability.
Rofandi Rori Aditiar Warandi, Maulana Furqon, Dadang Gandara
et al.
This study was conducted to develop an improved coffee grinder tailored for small and medium enterprises (SMEs) to address challenges due to limited resources. The development phase included a broad description, sizing, defining main components, developing technical drawings, manufacturing, and conducting functional tests. The machine had an overall dimension of 743 mm in length, 367 mm in width, and 580 mm in height. It was powered by a 1 HP induction motor with a rotation speed of 1400 rotations per minute (RPM) and a shaft diameter of 19 mm. The prototype achieved a grinding capacity of 23.8 kg/h for acceptable coffee grounds while maintaining a constant grind size, essential for achieving the best flavor and aroma. However, the noise level reached 86.5 dB, requiring hearing protection for prolonged usage. Future investigations should focus on exploring alternative materials and developing noise mitigation strategies, as noise reduction efforts can enhance operator physical and mental health in the coffee production process.
In the context of low-pressure casting, an excessive inlet velocity may result in the introduction of an oxide film and air into a liquid metal, leading to the formation of a two-layer film structure within the casting. Such defects can significantly degrade the mechanical properties of the castings. In order to optimize the advantages of low-pressure casting, an empirically designed equation for the inlet velocity was formulated and the concept of critical inlet velocity was further refined. A comprehensive numerical simulation was conducted to meticulously analyze the liquid metal spreading phase within the cavity. Subsequently, low-pressure casting experiments were carried out with actual castings of an A357 alloy, using two different entrance velocities—one critical and the other exceeding the critical entrance velocity. Tensile test specimens were extracted from the castings for the comparative evaluation of mechanical properties. It was observed that the average tensile strength of specimens cast at the critical inlet velocity exhibited a notable 16% enhancement. In contrast, specimens cast at velocities exceeding the critical inlet velocity manifested the presence of double oxide film defects. This evidence suggests that casting at a velocity faster than the critical inlet velocity leads to the formation of double oxide film defects, which in turn reduces the mechanical properties of the castings.
Francesco Arcidiacono, Alessandro Ancarani, Carmela Di Mauro
et al.
PurposeSmart Manufacturing (SM) lies at the core of Industry 4.0. Operations management research has identified several factors influencing firms’ ability to adopt SM. However, a clear understanding of capabilities needed to progress in SM is still missing. This paper aims to investigate how absorptive capacity (AC) allows firms to advance in SM and explore how managerial antecedents support the capacity to absorb SM-related knowledge at different stages of SM adoption.Design/methodology/approachThis study adopts an exploratory approach through multiple case studies. Twelve firms, operating as part of the automotive supply chain and exhibiting different stages of SM adoption, constitute the sample.FindingsThe results suggest that advancement in SM requires firms to progressively reinforce their AC. Firms’ ability to acquire and assimilate SM knowledge is supported by managerial antecedents encompassing integrative capacities to bridge old and SM technologies, managerial cognition through the clear alignment of SM technologies with strategic goals and knowledge development capabilities through practices oriented to provide senior managers with SM competences.Originality/valueThe findings contribute to SM research by suggesting that AC is a crucial dynamic capability for SM adoption. The results also provide evidence-grounded recommendations to firms engaged in the digital transformation on the managerial capabilities needed to support AC and to progress from lower to higher stages of SM.
Isaac Olushola Ogunkola, Oyinloye Emmanuel Abiodun, Babatunde Ismail Bale
et al.
Background: The Mpox outbreak awakened countries worldwide to renew efforts in epidemiological surveillance and vaccination of susceptible populations. In terms of Mpox vaccination, various challenges exist in the global south, which impede adequate vaccine coverage, especially in Africa. This paper reviewed the situation of Mpox vaccination in the global south and potential ameliorative approaches. Methods: A review of online literature from PubMed and Google Scholar concerning Mpox vaccination in countries belonging to the ‘global south’ category was done between August and September, 2022. The major focus areas included inequity in global vaccine distribution, challenges impeding vaccine coverage in the global south, and potential strategies for bridging the gap in vaccine equity. The papers that met the inclusion criteria were collated and narratively discussed. Results: Our analysis revealed that, while the high-income countries secured large supplies of the Mpox vaccines, the low- and middle-income countries were unable to independently access substantial quantities of the vaccine and had to rely on vaccine donations from high-income countries, as was the case during the COVID-19 pandemic. The challenges in the global south particularly revolved around inadequate vaccine production capacity due to lack of qualified personnel and specialized infrastructure for full vaccine development and manufacturing, limited cold chain equipment for vaccine distribution, and consistent vaccine hesitancy. Conclusion: To tackle the trend of vaccine inequity in the global south, African governments and international stakeholders must invest properly in adequate production and dissemination of Mpox vaccines in low- and middle-income countries.
Metal additive manufacturing has reached a level where products and components can be directly fabricated for applications requiring small batches and customized designs, from tinny body implants to long pedestrian bridges over rivers. Wire-fed directed energy deposition based additive manufacturing enables fabricating large parts in a cost-effective way. However, achieving reliable mechanical properties, desired structural integrity, and homogeneity in microstructure and grain size is challenging due to layerwise-built characteristics. Manufacturing processes, alloy composition, process variables, and post-processing of the fabricated part strongly affect the resultant microstructure and, as a consequence, component serviceability. This paper reviews the advances in wire-fed directed energy deposition, specifically wire arc metal additive processes, and the recent efforts in grain tailoring during the process for the desired size and shape. The paper also addresses modeling methods that can improve the qualification of fabricated parts by modifying the microstructure and avoid repetitive trials and material waste.
Vadim R. Gasiyarov, Andrey A. Radionov, Boris M. Loginov
et al.
The strategic initiative aimed at building “digital metallurgy” implies the introduction of diagnostic monitoring systems to trace the technical condition of critical production units. This problem is relevant for rolling mills, which provide the output and determine the quality of products of metallurgical companies. Making up monitoring systems requires the development of digital shadows and coordinate observers, the direct measurement of which is either impossible or associated with numerous difficulties. These coordinates include the spindle torque applied by the spring-transmitting torque from the motor to the rolling stand rolls. The development and research are conducted by the example of the electromechanical systems of the horizontal stand at the plate mill 5000. The stand electric drive characteristics are given, and the emergency modes that cause mechanical equipment breakdowns are analyzed that. The relevance of analyzing transient torque processes in emergency modes has been accentuated. The paper points to the shortcomings of the system for elastic torque direct measurement, including low durability due to the harsh operating conditions of precision sensors. It also highlights the need to install the measuring equipment after each spindle. The disadvantage of the previously developed observer is the function of calculating the electric drive speed derivative. This causes a decrease in noise immunity and signal recovery accuracy. The contribution of this paper is building a digital elastic torque observer that has advantages over conventional technical solutions, based on the theoretical and experimental studies. The technique for virtual observer adjustment was developed and tested in the Matlab-Simulink software package. For the first time, a comprehensive analysis was conducted for spindle elastic torques in emergency modes that caused equipment damage. An algorithm was developed for an emergency shutdown of a stand electric drive in the worst-case mode of strip retraction between work and backup rolls, due to the overlap of the strip on the roll. Further, the algorithm was tested experimentally. The criteria for diagnosing pre-emergencies was then justified. An adaptive motor-braking rate controller was developed. The developed observer and emergency braking system are in operation at the mill 5000. Long experimental research proved the efficiency of dynamic load monitoring and the reduction in the number of equipment breakdowns.
T. Aneesh, Chinmaya Prasad Mohanty, Asis Kumar Tripathy
et al.
The most effective and cutting-edge method for achieving a 0.004 mm precision on a typical material is to employ die-sinking electrical discharge machining (EDM). The material removal rate (MRR), tool wear rate (TWR), residual stresses, and crater depth were analyzed in the current study in an effort to increase the productivity and comprehension of the die-sinking EDM process. A parametric design was employed to construct a two-dimensional model, and the accuracy of the findings was verified by comparing them to prior research. Experiments were conducted utilizing the EDM machine, and the outcomes were assessed in relation to numerical simulations of the MRR and TWR. A significant temperature disparity that arises among different sections of the workpiece may result in the formation of residual strains throughout. As a consequence, a structural model was developed in order to examine the impacts of various stress responses. The primary innovations of this paper are its parametric investigation of residual stresses and its use of Haynes 25, a workpiece material that has received limited attention despite its numerous benefits and variety of applications. In order to accurately forecast the output parameters, a deep neural network model, more precisely, a multilayer perceptron (MLP) regressor, was utilized. In order to improve the precision of the outcomes and guarantee stability during convergence, the L-BFGS solver, an adaptive learning rate, and the Rectified Linear Unit (ReLU) activation function were integrated. Extensive parametric studies allowed us to determine the connection between key inputs, including the discharge current, voltage, and spark-on time, and the output parameters, namely, the MRR, TWR, and crater depth.
Badhoutiya Arti, Darokar Hemant, Verma Rajesh Prasad
et al.
In an era characterised by mounting environmental concerns and a growing awareness of the critical need for sustainability, the manufacturing industry stands at a crossroads. “Regenerative Manufacturing” emerges as a visionary strategy that not only tries to lower the ecological footprint of production but also seeks to restore and rejuvenate ecosystems, communities, and economies. This abstract provides a look into the profound potential of regenerative manufacturing, showcasing its main principles, processes, and its transformational impact on the future of design and production. Regenerative manufacturing signifies a fundamental transformation in the conceptualization, production, and use of items. The manufacturing process incorporates sustainability, circularity, and resilience throughout all its stages, encompassing material selection, design, production, distribution, and end-of-life concerns. The holistic approach discussed here places significant emphasis on the reduction of waste, optimisation of energy usage, and the utilisation of regenerative resources. This strategy aims to establish a regenerative cycle that actively supports the nourishment of the environment, rather than causing its depletion By employing novel methodologies such as biomimicry and generative design, this approach effectively harnesses the knowledge inherent in nature to stimulate the development of sustainable solutions. The regenerative manufacturing paradigm places significant emphasis on the core principles of collaboration and inclusivity. The recognition of the interconnection of all stakeholders is evident, encompassing producers, designers, customers, and local communities. By promoting openness and upholding ethical standards, this approach facilitates socially responsible production techniques that enhance the agency of local economies, safeguard cultural heritage, and prioritise the welfare of employees. The revolutionary capacity of regenerative manufacturing extends beyond the scope of specific goods and sectors. The power of this phenomenon lies in its ability to transform economic systems, facilitating a shift away from a linear model characterised by the processes of extraction, production, and disposal, towards a regenerative and circular economy. This transition offers not alone ecological advantages, but also financial robustness and enduring success.
Abstract The bullwhip is a well-known phenomenon in supply chain management. Whereas past research has focused on factors like supply rationing, batch-size, lead-time etc., mainly from an analytical perspective. This paper broadens the research by specifically examining the impact from production capacity constraints not only on demand (order size) but also on inventory levels and supply chain cost. The results confirm past research and brings new insights in the impact on component and compound bullwhip effect behavior across supply chain echelons by showing that production capacity acts as a damper on the bullwhip effect.
Summary: The electrification revolution in the automobile and other industries demands annual production capacity of batteries of at least 102 GWh, which presents a twofold challenge: supply of key materials such as cobalt and nickel and recycling when batteries are retired from use. Pyrometallurgical and hydrometallurgical recycling are currently used in industry but suffer from complexity, high costs, and secondary pollution. Here we report a molten-salt-based method for direct recycling (MSDR) that is environmentally benign and creates value on the basis of a techno-economic analysis using real-world data and price information. We also experimentally demonstrate the feasibility of MSDR by upcycling a low-nickel polycrystalline LiNi0.5Mn0.3Co0.2O2 (NMC) cathode material into Ni-rich (Ni > 65%) single-crystal NMCs with increased energy density (>10% increase) and outstanding electrochemical performance (>94% capacity retention after 500 cycles). This work may open opportunities for closed-loop recycling of electric vehicle batteries and manufacturing of next-generation NMC cathode materials.
The ability to produce metal matrix nanocomposites via pressing and infiltration was validated. Al/TiC nanocomposite was used as the model material. Pressing the powder in a die yielded cylindrical specimens with a green density of 1.98 ± 0.05 g/cm<sup>3</sup>, which was increased to only 2.11 ± 0.12 g/cm<sup>3</sup> by sintering. Direct infiltration of the pressed specimens at 1050 °C for 3.5 h yielded specimens with a density of 3.07 ± 0.08 g/cm<sup>3</sup>, an open porosity of 3.06 ± 1.40%, and an areal void fraction of 8.09 ± 2.67%. The TiC nanoparticles were verified to be well dispersed using energy-dispersive X-ray spectroscopy. The measured hardness of 64 ± 3 HRA makes it a promising material for structural applications in industries such as aerospace and automotive.
The present study examines the fatigue of friction stir welded (FSW) aluminum 6061, 7075, 1060 joints followed by (i) in situ and sequential rolling (SR) processes, (ii) plastic burnishing (iii) solution-treatment artificial aging (STA), (iv) local alloying through depositing thin copper foils, and (v) inserting alumina powder in the weld nugget zone (NZ). The microstructural features and fatigue life of post-processed joints were compared with those of as-welded joints. The in situ rolling technique offered simultaneous rolling and welding operations of aluminum joints, while through the sequential rolling process, the top surface of FSW joints was rolled after the welding process. The fatigue life of in situ rolled samples was increased as the ball diameter of welding tool increased. The fatigue life of friction stir welded joints after a low-plasticity burnishing process was noticeably promoted. The addition of 1 wt.% alumina in the NZ of joints resulted in a significant elevation on fatigue life of friction stir spot welded joints, while an increase in alumina powder to 2.5 wt.% adversely affected fatigue strength. Weld NZ was alloyed through the insertion of copper foils between the faying surfaces of joints. This localized alloy slightly improved the fatigue life of joints; however, its effects on fatigue life were not as influential as STA heat-treated or in situ rolled joints. The microstructure of weld joints was highly affected through post-processing and treatments, resulting in a substantial influence on the fatigue response of FSW aluminum joints.
María Paula Fiorucci, Alberto Cuadrado, Alejandro Yánez
et al.
Large thoracic defects need to be reconstructed to restore inner organs protection and normal ventilation. Early rigid implants have provided the stabilization of the ribcage; however, those have been associated with breathing restrictions. The evolution of additive manufacturing has enabled the production of 3D custom-made thoracic implants. This has led to case reports on reconstructions with these prostheses, particularly for large anterior resections. A novel design of thoracic implant with dynamic capacity has already been reported, with promising short-term outcomes. However, specific biomechanical studies are needed to clarify its mechanical behaviour. A study of the evolution of the design of dynamic thoracic implants was carried out and such implants were biomechanically tested. Furthermore, finite element analyses were carried out to obtain a simple and reliable model to predict the implant behaviour, considering a rib and its costal cartilage. In the models, the stiffness and stress distribution along the implant and the bone showed that the reconstructions exhibited adequate mechanical behaviour. One of the designs provided a flexibility that closely matched the native model and the maximum stress values did not exceed the 30% of the yield strength of Ti-6Al-4V. The implants strength was demonstrated to be sufficient under tested conditions.
Materials of engineering and construction. Mechanics of materials
Milling tools with a large length–diameter ratio are widely applied in machining structural features with deep depth. However, their high dynamic flexibility gives rise to chatter vibrations, which results in poor surface finish, reduced productivity, and even tool damage. With a passive tuned mass damper (TMD) embedded inside the arbor, a large length–diameter ratio milling tool with chatter-resistance ability was developed. By modeling the milling tool as a continuous beam, the tool-tip frequency response function (FRF) of the milling tool with TMD was derived using receptance coupling substructure analysis (RCSA), and the gyroscopic effect of the rotating tool was incorporated. The TMD parameters were optimized numerically with the consideration of mounting position based on the maximum cutting stability criterion, followed by the simulation of the effectiveness of the optimized and detuned TMD. With the tool-tip FRF obtained, the chatter stability of the milling process was predicted. Tap tests showed that the TMD was able to increase the minimum real part of the FRF by 79.3%. The stability lobe diagram (SLD) was predicted, and the minimum critical depth of cut in milling operations was enhanced from 0.10 to 0.46 mm.
3D NAND technical development and manufacturing face many challenges to scale down their devices, and metrology stands out as much more difficult at each turn. Unlike planar NAND, 3D NAND has a three-dimensional vertical structure with high-aspect ratio. Obviously top-down images is not enough for process control, instead inner structure control becomes much more important than before, e.g. channel hole profiles. Besides, multi-layers, special materials and YMTC unique X-Tacking technology also bring other metrology challenges: high wafer bow, stress induced overlay, opaque film measurement. Technical development can adopt some destructive methodology (TEM, etch-back SEM), while manufacturing can only use non-destructive method. These drive some new metrology development, including X-Ray, mass measure and Mid-IR spectroscopy. As 3D NAND suppliers move to >150 layers devices, the existing metrology tools will be pushed to the limits. Still, the metrology must innovate.
Electric apparatus and materials. Electric circuits. Electric networks, Production capacity. Manufacturing capacity
A low-cost parametric finite element thermal model is proposed to study the impact of the initial powder condition, such as diameter and packing density, on effective thermal conductivity as well as the impact of the laser power input on the final temperature distributions during selective laser melting (SLM). Stainless steel 304L is the material used, since it is not yet commercially available in SLM equipment and our main goal was to show the capabilities of the finite element method in the evaluation of power input in the process. The results from our sensitivity analysis showed that packing density has a greater impact on the final temperature distributions compared with powder diameter variance. However, overall the thermal conductivity of the powder only showed significant effects below the melting point, otherwise the thermal conductivity no longer affected the temperature distributions. Among the three different power inputs analyzed, the temperature profile demonstrated that power inputs of 100 and 200 W are recommended when printing SS-304L rather than 400 W, which generates too high temperature in the powder bed, a non-favorable behavior that can induce high residual stresses and material evaporation.
Sina Heshmati, Mohammad Sadegh Mazloomi, Philip David Evans
Machining grooves into the surface of pine and fir (Abies spp.) deckboards reduces undesirable checking that develops when “profiled” boards are exposed to the weather. We aim to develop improved profiles for Douglas fir, western hemlock and white spruce decking to reduce their susceptibility to checking, and understand how profile geometry influences the stresses that cause checking. We varied the width and depth of grooves in profiled deckboards, exposed deckboards to the weather, and measured checking and cupping of boards. A numerical model examined the effect of groove depth on the moisture-induced stresses in profiled spruce boards. Profiling significantly reduced checking, but increased cupping of deckboards made from all three species. Western hemlock checked more than the other two species. Profiles with narrow grooves (rib profiles) were better at restricting checking than profiles with wider grooves. A rib profile with deeper grooves developed smaller stresses than a rib profile with shallower grooves, and boards with the former profile checked less than boards with shallower grooves. We conclude that checking of profiled Douglas fir, western hemlock and white spruce decking is significantly reduced by changing profile geometry, and our results suggest the best profiles to reduce checking of all three species.