J. Manuf. Mater. Process., Volume 8, Issue 6 (December 2024) – 64 articles

AISI 304 is widely regarded as the most common austenitic stainless steel and is utilized in various household and industrial applications, including food handling equipment, machinery components, and heat exchangers. Its popularity stems from its excellent mechanical properties, corrosion resistance, and ease of manufacturing. Given its diverse applications, it is crucial to study the microstructural evolution and mechanical properties of the welded zone, especially considering the potential for weld decay during fusion welding. In this context, two critical thermal-dependent factors for ensuring high-quality welds are grain growth and hardness variation in the heat-affected zone (HAZ) during the welding process. This paper presents an innovative finite element (FE) model developed to analyze the grain growth and hardness reduction that occur in the HAZ during plasma arc welding (PAW) of AISI 304 steel for solid expansion tube (SET) technology. Using the commercial FE software SFTC DEFORM-3D™, a user subroutine was created that integrates a physics-based model with the Hall–Petch (H-P) equation to predict changes in grain size and hardness. This study introduces a comprehensive numerical model, encompassing the user subroutine, heat source fitting, and geometry, which accurately predicts the thermal phenomena associated with grain coarsening and hardness reduction in the HAZ during the welding of austenitic stainless steel. The results from the numerical model, including the customized user routines, show good agreement with experimental data, leading to a maximum error prediction of 10 HV in hardness, 30 µm in grain size, and 10% in HAZ extension. Full article

Laser powder bed fusion (LPBF) provides a novel approach with high complexity and freedom for material processing and design, and its special thermal history endows the material with anisotropic properties. By adding micro-alloying elements Nb and Ti into conventional 316L, the anisotropy of the novel austenitic stainless steel fabricated by LPBF, which is related to the laser heat input, was investigated. The refined microstructure of this steel was further strengthened with in situ-generated Nb-, Cr-, and Ti-rich nanoprecipitates at a specific location. The heat input affects the material anisotropy, and a lower heat input leads to stronger anisotropy in this steel. The as-built parts at a low heat input in the horizontal and vertical planes exhibited finer microstructures compared to those fabricated at a high heat input. The epitaxial growth of the grains associated with the thermal gradient resulted in the vertical-section grain size being generally larger than that of the horizontal section. As a result, the low-heat-input parts with a finer grain are also stronger in the horizontal direction, with yield and tensile strengths approaching 0.9 and 1.2 GPa, respectively. Meanwhile, the microstructural changes due to the high heat input imparted a better ductility of parts in different sections (a 3.15% and 4.4% increase in the horizontal and vertical directions, respectively). Its mechanical properties depend mainly on the direction of stress coupled with intergranular friction during deformation in both coarse and fine grains. Full article

The present study focuses on advancing one of the most popular AM techniques, namely, laser powder bed fusion (LPBF) technology, which has the ability to produce complex geometry parts with minimum material waste but continues to face challenges in minimizing the surface roughness. For this purpose, a novel hybrid manufacturing technology, which applies in a single setup (in-envelope) both LPBF technology and high-speed machining, was examined in this research for the fabrication of tensile specimens with three different surface finish conditions: as-built, hybrid (in-envelope machining) and post-machining (out-of-envelope) on Inconel^® alloy 718, hereafter referred to as IN718. As the application of the IN718 alloy in service is typically specified in the precipitation-hardened condition, three different heat treatments were applied to the tensile specimens based on the most promising thermal cycles identified previously for room-temperature tensile properties by the authors. The as-built (AB) specimens had the highest average surface roughness (R_a) of 5.1 μm ± 1.6 μm, which was a significant improvement (five-fold) on the hybrid (1.0 μm ± 0.2 μm) and post-machined (0.8 μm ± 0.5 μm) surfaces. The influence of this surface roughness on the mechanical properties was studied both at ambient temperature and at 650 °C, which is close to the maximum service temperature of this alloy. Regardless of the surface conditions, the room-temperature mechanical properties of the as-fabricated IN718 specimens were within the range of properties reported for standard wrought IN718 in the annealed condition. Nonetheless, detailed examination of the strain localization behavior during tensile testing using digital image correlation showed that the IN718 specimens with AB surfaces exhibited lower ductility (global and local) relative to the hybrid and post-machined ones, most likely due to the higher surface roughness and near-surface porosity in the former. At 650 °C, even though the mechanical properties of all the heat-treated IN718 specimens surpassed the minimum specifications for the wrought precipitation-hardened IN718, the AB surface condition showed up to 4% lower strength and 33–50% lower ductility compared with the hybrid and PM surface conditions. Microfocus X-ray computed tomography (µXCT) of the fractured specimens revealed the presence of numerous open cracks on the AB surface and a predisposition for the near-surface pores to accelerate rupture, leading to premature failure at lower strains. Full article

Biomaterials have assumed a decisive role in modern medicine by enabling significant advancements in medical care practices. These materials are designed to interact with biological systems, offering substantial solutions for various medical needs. In this research, bioceramic materials consisting of a bioactive hydroxyapatite-based matrix with Ti nanoparticles were processed as promising materials. These bioceramics were obtained using mechanical milling, uniaxial pressing, and sintering as powder processing techniques. This study evaluates the effect of Ti additions on the structural, electrochemical, and mechanical properties of the hydroxyapatite ceramic material. Titanium additions were about 1, 2 and 3 wt%. The experimental results demonstrate that the biocomposite’s structure has two hexagonal phases: one corresponding to the hydroxyapatite matrix and the other to the Ti as a reinforced phase. The biomaterials’ microstructure is completely fine and homogeneous. The biomaterial reinforced with 1 wt. % Ti exhibits the best mechanical behavior. In this context, electrochemical tests reveal that bioceramics can achieve stability through an ion adsorption mechanism when exposed to a physiological electrolyte. Bioceramics, particularly those containing 1%Ti, develop their bioactivity through the formation of a high-density hydroxide film during a porous sealing process at potentials around −782.71 mV, with an ionic charge transfer of 0.43 × 10⁻⁹ A/cm². Finally, this biofilm behaves as a capacitor Cc = 0.18 nF/cm², resulting in lower ionic charge transfer resistance (Rct = 1.526 × 106 Ω-cm²) at the interface. This mechanism promotes the material’s biocompatibility for bone integration as an implant material. Full article

One major disadvantage of fused filament fabricated components (FFF) is its well-known anisotropy, which results from the layer-wise adding of material, and that it is not always possible to avoid loading in the layer build-up direction. In particular, components that are exposed to multi-axial load conditions must manage with reduced tensile strength in the build-up direction. This work is therefore concerned with improving the tensile strength transverse to the layering by changing the layer structure without directly changing the material itself. Therefore, the print-defining G-Code was modified to change the arrangement between the layers. The effectiveness of this method was investigated by means of tensile tests using thermoplastic samples made of Acrylonitrile Styrene Acrylate (ASA), Poly Cyclohexylenedimethylene Terephthalate Glycol (PCTG), Poly Ethylene Terephthalate Glycol (PETG) and Poly Lactic Acid (PLA) for layer thicknesses of 0.16 mm and 0.28 mm. The results show that the G-Code modification generally resulted in an increase in tensile strength. For PETG, an improvement of 25% was achieved. Full article

Directed Energy Deposition Laser Beam (DED-LB) is a promising additive manufacturing technique that uses a laser source and a powder stream to build or repair metal components. Repair applications offer significant economic and environmental benefits but are more challenging to develop, especially for components that are difficult to process due to their intricate geometries and materials. Process conditions can change precipitously, and it is essential to implement monitoring systems that ensure high process stability and, consequently, superior end-product quality. In the present work, a mid-wave infrared coaxial camera was used to monitor the melt pool geometry. To simulate the challenging repair process conditions of the DED-LB process, experimental tests were carried out on substrates with different thicknesses. The stability of the deposition process on nickel-based superalloys was analyzed by means of MATLAB algorithms. Thus, the effect of open-loop and closed-loop monitoring with back control on laser power on the process conditions was assessed and quantified. Metallographic analysis of the produced samples was carried out to validate the analyses performed by the monitoring system. The occurrence of production defects (lack of fusion and porosity) related to parameters not directly controllable by monitoring systems, such as penetration depth and dilution, was determined. Full article

In competitive industry, economical and environmentally friendly production techniques are essential. In this sense, cleaner and more sustainable machining techniques are the industry’s focus. In addition to green methods, effective parametric control is necessary for hard-to-cut materials, particularly titanium Ti-6Al-4V, which is extensively used in a diversity of industries, including aerospace, medical, and military applications. Therefore, the current study aims to improve the machining performance of Ti-6Al-4V alloy using sustainable lubrication conditions. The effect of Al₂O₃ nanoparticles based on the minimum quantity lubrication (N-MQL) condition on surface quality and productivity are compared with minimum quantity lubrication (MQL). The performance measures, including surface roughness (Ra), material removal rate (MRR), and temperature, are evaluated at three machining variables, i.e., cutting speed (V_c), feed rate (f), and depth of cut (a_p). These performance measures are further assessed by tool wear and surface morphology analysis. a_p, f, and V_c are the most influencing parameters for Ra, MRR, and temperature, regardless of lubrication mode. The optimized values of RA of 0.728443 µm, MRR of 2443.77 m³/min, and temperature of 337 °C are achieved at N-MQL. For the N-MQL state, the optimized values of Ra of 0.55 µm, MRR of 2579.5 m³/min, and temperature of 323.554 °C are attained through a multi-response optimization desirability approach. Surface morphology analysis reveals a smooth machined surface with no obvious surface flaws, such as feed marks and adhesion, under N-MQL conditions, which significantly enhances the surface finish of the parts. The machining performance under the N-MQL condition has been enhanced considerably in terms of an improvements in surface finish of 32.96% and MRR of 11.56%, along with a decrease in temperature (17.22%) and higher tool life (326 s) than MQL. Furthermore, Al₂O₃ is advised over MQL because it uses less energy and has reduced tool wear and improved surface quality, and it is a cost-effective and sustainable fluid. Full article

Metal Binder Jetting (BJT/M) has emerged as a promising additive manufacturing (AM) technology for the realization of complex parts using a wide range of metal alloys. This technology offers several advantages, such as design flexibility, reduced lead times, a high building rate, and the ability to fabricate intricate geometries that are difficult or impossible to achieve with conventional manufacturing methods. Cobalt Chromium Molybdenum (CoCrMo) alloys are particularly suitable for demanding applications in the aerospace, biomedical, and industrial sectors that require high strength and hardness, corrosion resistance, and biocompatibility. In this work, ten cubic and ten tensile samples were printed with a layer height of 50 µm using the shell printing method, debound and sintered at 1325 °C for 4 h, with the aim of investigating the properties of CoCrMo parts made using BJT technology. A density of 7.88 g/cc was obtained from the Archimede’s test. According to the printing and sintering parameters, an average hardness of 18.5 ± 1.8 HRC and an ultimate tensile strength of 520.5 ± 44.6 MPa were obtained. Finally, through a microstructure analysis, an average grain size of 182 ± 14.7 µm was measured and the presence of an intergranular Cr-rich phase and Mo-rich carbides was detected. Full article

Polymer composites have been utilized across various industries, especially in transportation, for many years. With a growing emphasis on sustainable production resources, the industry increasingly favours composite materials reinforced with natural fibres or particles. Unlike conventional fibres such as glass, carbon, or aramid, natural fibres typically have low compatibility with polymer matrices, often necessitating pretreatment to enhance bonding. In this study, coir fibres were physically and chemically treated with sodium bicarbonate solutions at varying concentrations (5–15%) and immersion durations (0–5 days). The treated fibres were then mixed into epoxy resin and poured into moulds to produce test specimens for evaluating mechanical properties. The fibre content in the composites ranged from 10 to 20%. Statistical analysis revealed that immersion time significantly affects all mechanical properties tested (tensile modulus, tensile strength, strain, and impact strength). Solution concentration significantly influences tensile modulus and strain, while fibre content significantly affects tensile modulus and strength. The conducted optimization shows that the best mechanical properties are achieved with the minimum tested coir fibre content of 10%. Maximum stiffness and strength can be expected with the longest immersion time of 5 days in the highest solution concentration of 15%. The best strain and impact strength properties, however, are observed at the lowest solution concentration of 5%. Full article

Automotive structural components from Advanced High-Strength Steels (AHSS) can be manufactured with Flexible Roll Forming (FRF). The application of FRF in the automotive industry is limited due to flange wrinkling defects that increase with material strength. The new Incremental Shape Rolling process (ISR) has been shown to reduce wrinkling severity compared to FRF and therefore presents a promising alternative for the manufacture of high-strength automotive components. The current work analyzes for the first time the mechanisms that lead to wrinkling reduction in ISR based on the critical stress conditions that develop in the flange. For this, finite element process models are validated with experimental forming trials and used to investigate the material deformation and the forming stresses that occur in FRF and ISR when forming a variable-width automotive component. The results show that in ISR, the undeformed flange height decreases with increasing forming; this increases the critical buckling and wrinkling stresses with each forming pass and prevents the development of wrinkles towards the end of the forming process. In contrast, in FRF, the critical buckling or wrinkling stress is constant, while the longitudinal compressive stress in the flange increases with the number of forming passes and exceeds the critical stress. This leads to the development of severe wrinkles in the flange. Full article

This study systematically compares the surface polishing performance and finishing results of the following two different electrolytic plasma polishing technologies on stainless steel AISI 316L: (i) plasma electrolytic polishing (PEP) and (ii) plasma electrolytic polishing jet (PEP-Jet). The two techniques are compared against an industrial standard polishing method, electropolishing (EP). For comparable energy density consumption, the samples treated with the PEP-Jet technique showed the highest removal rate, up to three times less than the initial roughness, resulting in the highest surface roughness reduction from Sa = 249 nm to Sa = 81 nm. Microstructure characterization of samples treated using PEP-Jet also showed well-defined crystalline grain boundaries with a distinct appearance of predominantly inter-crystalline structures within individual grains, which is uncommon with EP techniques. The surfaces treated using PEP-Jet exhibited the lowest corrosion rate of $6.79\times {10}^{-5}$ mm/year, and no signs of areal corrosion were detected in the performed corrosion tests in contrast with the other samples and their respective treatments. The comparative analysis revealed that the high ionic current delivered by the electrolyte jet flow in the PEP-Jet process effectively stabilizes the plasma at the contact zone, thereby enhancing the plasma polishing of austenitic stainless steel samples. The efficacy of this method has been demonstrated in terms of reducing energy consumption and enhancing corrosion resistance in comparison with (PEP) and (EP) as state-of-the-art processes in corrosive environments of high-alloyed steel. Full article

Processing high-performance aluminum alloys, including 6xxx and 7xxx series, via laser additive manufacturing (AM) processes poses significant challenges, primarily due to the rapid cooling rates inherent in these processes, which often result in solidification cracking and metallurgical defects. This study aimed at producing dense, crack-free samples of Al6061 alloys, using the laser powder bed fusion (L-PBF) process. Taguchi’s method of design of experiments was employed to study the effects of laser power, scanning speed, and hatch spacing on the L-PBF process parameters for Al6061. Two types of samples were fabricated: cubic samples for density and microstructural analyses; and dog bone samples for tensile testing. The microstructure, density, mechanical properties, fractography, and material composition of the L-PBF Al6061 parts were investigated. Based on our experimental findings, an optimal process window is suggested, with a laser power of 200–250 W, scanning speed of 1000 mm/s, and hatch spacing of 140 µm, resulting in complete melting within the energy density range of 44–50 ${\mathrm{J}/\mathrm{mm}}^3$. This work demonstrates that adjusting processing conditions—specifically, increasing the energy density from 25.51 ${\mathrm{J}/\mathrm{mm}}^3$ to 44.64 ${\mathrm{J}/\mathrm{mm}}^3$—leads to a reduction in porosity from approximately 5% to below 1%, significantly improving the density and quality of the parts fabricated using L-PBF. Full article

With the development of robotic welding automation, there is a strong interest in welding seam identification and localization methods with high accuracy, real-time performance, and robustness. This paper proposed a 3D workpiece weld identification and localization method based on DBSCAN (density-based spatial clustering of applications with noise) to realize stable feature extraction for multiple joint types. Firstly, this method employs combinatorial filtering to effectively eliminate non-target point clouds, including outliers and installation platform point clouds, which can minimize the computational load. Secondly, DBSCAN is used to classify workpiece point clouds into different clusters, which can be used for point cloud segmentation of flat workpieces and curved workpieces. Thirdly, the edge detection and feature extraction methods are used to obtain joint gap and weld feature points while combining the information of point clouds for different types of welds. Finally, based on the identification and localization of the welds, welding path planning and attitude planning are implemented. Experimentation results indicated that the proposed method exhibits robustness across various types of welded joints, including butt joints with straight seams, butt joints with curved seams, butt joints with curved workpieces, and lap joints. Meanwhile, the average error of joint gap detection was 0.11 mm and the processing time of a 90 mm straight-seam butt joint is 701.12 ms. Full article

Freeform carbon fibres were 3D-printed from CH₃OH:H₂O mixtures using hyperbaric-pressure laser chemical vapour deposition (HP-LCVD). The experiment overlapped a region of known diamond growth, with the objective of depositing diamond-like carbon without the use of plasmas or hot filaments. A high-pressure regime was investigated for the first time through the precursor’s critical point. Seventy-two C-fibres were grown from 13 different CH₃OH:H₂O mixtures at total pressures between 7.8 and 180 bar. Maximum steady-state axial growth rates of 14 µm/s were observed. Growth near the critical point was suppressed, ostensibly due to thermal diffusion and selective etching. In addition to nanostructured graphite, various carbon allotropes were synthesised at/within the outer surface of the fibres, including diamond-like carbon, graphite polyhedral crystal, and tubular graphite cones. Several allotropes were oversized compared to structures previously reported. Raman spectral pressure–temperature (P-T) maps and a pictorial P-T phase diagram were compiled over a broad range of process conditions. Trends in the Raman I_D/I_G and I_2D/I_G intensity ratios were observed and regions of optimal growth for specific allotropes were identified. It is intended that this work provide a basis for others in optimising the growth of specific carbon allotropes from methanol using HP-LCVD and similar CVD processes. Full article

The present study introduces an integrated software approach that provides an automated product design toolkit for customized products like knives, incorporating topology optimization (TO) and numerical simulations in order to streamline engineering workflows during the product development procedure. The modeling framework combines state-of-the-art technologies into a single platform, enabling the design and the optimization of mechanical structures with minimal human intervention. In particular, the proposed solution leverages artificial intelligence (AI), shape optimization methods, and computational tools in order to iteratively optimize material utilization as well as the design of products based on certain criteria. By embedding simulation within the design optimization loop, the developed software module ensures that performance constraints are respected throughout the design process. The case studies are concentrated in designing knives, demonstrating the platform’s ability to reduce design time, enhance product performance and provide rapid iterations of structurally optimized geometries. Finally, it should be noted that this research showcases the potential of integrated modeling technologies towards the transformation of traditional design paradigms, in this way contributing to faster, more reliable and efficient product development in various engineering industries through the training and deployment of AI models in these scientific fields. Full article

Industries operating in extreme conditions demand materials with exceptional strength, fatigue resistance, corrosion resistance, and formability. While AA5052 alloy is widely used in such industries due to its high fatigue strength and corrosion resistance, its strength frequently falls short of stringent standards. For AA5052 alloy, this study explores the combined use of solutionizing and cryo-rolling, followed by annealing, to improve strength. Although several alloys have been reported to undergo solution treatment before cryo-rolling, this study focuses on how post-processing via annealing can lessen the formability constraints usually connected to conventional cryo-rolling. The study sheds light on the ways that solutionizing, cryo-rolling, and annealing interact to affect the alloy’s mechanical characteristics. Microstructure analysis shows that solutionizing improves the grain structure by reducing dynamic recovery, promoting dislocation density, and facilitating precipitate formation. Sheets subjected to solutionizing + cryo-rolling and partially annealed at 250 °C produce optimal results. Interestingly, formability is decreased when cryo-rolling alone is used instead of cold rolling, whereas formability is successfully increased when solutionizing is used. Comparing solutionized + cryo-rolled sheets that are partially annealed at 250 °C to cold-rolled sheets that are annealed at the same temperature, the former show notable quantitative improvements: a notable 17% increase in ultimate strength, a 10% boost in yield strength, and a noteworthy 13% enhancement in microhardness. Formability has improved with the solutionized + cryo-rolled specimens by annealing. This proposed approach led to noticeable gains in formability, hardness, and strength, which would significantly improve material performance for industrial applications. Full article

The P91 martensitic steel and 304L austenitic stainless steels are two mainly used structural steels in power plants. The major problem in conventional multipass tungsten inert gas (TIG) welding of P91/304L steel is high heat input and joint distortion, increased cost and time associated with V groove preparation, filler rod requirement, preheating and welding in multiple passes, and labor efforts. Hence, in this study, a novel approach of robotically operated activated flux TIG (A-TIG) welding process and thin AlCoCrFeNi_2.1 eutectic high entropy alloy (EHEA) sheet as the interlayer was used to weld 6.14 mm thick P91 and 304L steel plates with 02 passes in butt joint configuration. The joints were qualified using visual examination, macro-etching, X-ray radiography testing and angular distortion measurement. The angular distortion of the joints was measured using a coordinate measuring machine (CMM) integrated with Samiso 7.5 software. The quality of the A-TIG welded joints was compared to the joints made employing multipass-TIG welding process and Inconel 82 filler rod in 07 passes. The A-TIG welded joints showed significant reduction in angular distortion and higher productivity. It showed a 55% reduction in angular distortion and 80% reduction in welding cost and time compared to the multipass-TIG welded joints. Full article

Recently, there has been much scholarly research on the applications of CNTs in various fields which can be attributed to their outstanding properties. For that matter, machining processes as the backbone of manufacturing technologies have also benefited greatly from the introduction of CNTs. However, there is a lack of papers that provide a holistic overview on potential applications, which impedes focused and robust research in their application. In this work, after providing an outline of the methods used in increasing the productivity of machining processes, we will review the ways in which CNTs, known for their remarkable mechanical, chemical, electrical, and thermal characteristics, enhance the productivity of machining processes. We emphasize fit-for-purpose applications to determine the fate of CNTs use in machining processes. We examine the applications of CNTs in enhancing the mechanical characteristics of cutting tools, which include increased wear resistance, strength, and thermal conductivity, thereby extending tool life and performance. Additionally, this work highlights the application of nanofluids in MQL systems, where CNTs play a crucial role in reducing friction and enhancing thermal management, leading to reduced lubricant usage while maintaining cooling and lubrication effectiveness. Full article

In Laser Powder Bed Fusion, process material defects such as a lack of fusion, powder inclusions and cavities occur repeatedly by chance. These stochastically distributed defects can significantly reduce the mechanical performance of the components during operation. Possible in situ repair solutions such as multiple remelting of specific layer areas are promising approaches to avoid these defects in the finished component, thus improving the overall properties. In this context, the present study investigates the remelting of artificially introduced defects using the example of M789 tool steel. In the first step, the process parameter settings and mechanical properties were evaluated using a tensile test, and the density of the local repair was examined using X-ray computer tomography and a metallographic analysis. The results demonstrate that the mechanical properties of the tensile test are comparable with those of the reference samples while successfully increasing the component quality. This indicates that defects that arise during the process can be remelted without the loss of mechanical characteristics. Full article

In this work, the effect of high-entropy alloy powder preparation on the coatings deposited via high-velocity oxygen fuel sprayings was studied. The powders of FeNiCoCrMo_0.5Al_1.3 composition were prepared by milling and gas atomization. The structures, porosity, phase composition, and microhardness of the coatings produced from mechanically alloyed and gas-atomized powders were compared. The influence of milling parameters on the powder phase composition and morphology was studied. Milling at 600 rpm for 1.5 h allowed the production of mechanically alloyed powder with a homogeneous distribution of Fe, Ni, and Al and thin lamellas enriched with Co, Cr, and Mo. Despite the difference in the feedstock powders’ phase compositions, the phase compositions of the coatings deposited from mechanically alloyed and gas-atomized powders are the same consisting of BCC, FCC solutions, and oxide. The amount of FCC solutions and oxide in the coating depends on the size distribution of the sprayed powder. It was found that the phase composition and the properties of the coatings deposited from the mechanically alloyed and gas-atomized powders of similar sizes are similar. Full article

The wettability and high-temperature mechanical properties of porous BN/Si₃N₄ ceramics brazed with SiTi22 (wt. %) filler were studied. It is manifested that SiTi22 filler presents remarkable wetting and spreading capabilities on the porous BN/Si₃N₄ ceramic surface. An interfacial reaction layer is generated at the interface, and the thickness of the reaction layer initially grows and subsequently remains constant with the escalation of temperature. Carbon coating modification is beneficial to the wettability and high-temperature mechanical properties of porous BN/Si₃N₄ ceramics. The wetting driving force is mainly controlled by the interfacial reaction at the three-phase line of the wetting front. The mechanical properties of the carbon-coated joints are significantly enhanced in comparison with uncoated joints. The joint strength attains a maximum value of roughly 73 MPa in the shear test implemented at 800 °C. The strength of the joint is significantly enhanced mainly due to the TiN_0.7C_0.3 particles that consume energy by changing the crack propagation direction, and the SiC nanowires strengthen the connection by bridging. Full article

The present study investigates the effects of fabrication parameters such as the nozzle temperature, the flow rate, and the layer thickness on the tensile strength of copper-filled metal-composite specimens. The selected material is a polylactic acid (PLA) filament filled with 65% copper powder. Two sets of 27 specimens each were fabricated, and equivalent tensile experiments were carried out using a universal testing machine. The experiments were planned according to the full factorial design, with three printing parameters, as well as three value levels for each parameter. The analysis revealed that the temperature and the flow rate had the greatest impact on the yielded tensile strength, with their contribution percentages being 42.41% and 22.16%, respectively. In addition, a regression model was developed based on the experimental data to predict the tensile strength of the 3D-printed copper-filled metal composite within the investigated range of parameters. The model was evaluated using statistical methods, highlighting its increased accuracy. Finally, an optimization study was carried out according to the principles of the desirability function. The optimal fabrication parameters were determined to maximize the tensile strength of the specimens: temperature equal to 220 °C, flow rate equal to 110%, and layer thickness close to 0.189 mm. Full article

The manufacturing industry must maintain high-quality standards while meeting customer demands for customization, reduced carbon footprint, and competitive pricing. To address these challenges, companies are constantly improving their production processes using quality management tools. A crucial aspect of this improvement is the root cause analysis of manufacturing defects. In recent years, there has been a shift from traditional knowledge-driven approaches to data-driven approaches. However, there is a gap in the literature regarding a systematic overview of both methodological types, their overlaps, and the challenges they pose. To fill this gap, this study conducts a scoping literature review of root cause analysis in manufacturing, focusing on both data-driven and knowledge-driven approaches. For this, articles from IEEE Xplore, Scopus, and Web of Science are examined. This review finds that data-driven approaches have become dominant in recent years, with explainable artificial intelligence emerging as a particularly strong approach. Additionally, hybrid variants of root cause analysis, which combine expert knowledge and data-driven approaches, are also prevalent, leveraging the strengths of both worlds. Major challenges identified include dependence on expert knowledge, data availability, and management issues, as well as methodological difficulties. This article also evaluates the potential of artificial intelligence and hybrid approaches for the future, highlighting their promises in advancing root cause analysis in manufacturing. Full article

Optimizing the energy efficiency of robotic workstations is a key aspect of industrial automation. This study focuses on the analysis of the relationship between the position of the robot base and its energy consumption and time aspects. A number of 6-axis robots, including the ABB IRB 120 robot, were investigated in this research by combining measurements and simulations using the energy consumption measurement module in the ABB RobotStudio 2024.1.1 environment. The objective of this study was to develop an energy consumption model that can identify the optimal robot positions to minimize energy costs and time losses. The results suggest that the strategic positioning of the robot has a significant impact on its performance and efficiency. These results demonstrate that the ideal working distance of the robots is approximately 50% of its maximum range, and displacements along the X and Z axes affect the energy and time consumption. These findings suggest the existence of a trade-off between time and energy efficiency, providing a basis for further research into the optimization of robotic systems. Thus, this work offers new perspectives for the design of efficient robotic workstations for cross-sensory applications. Full article

In the rapidly evolving landscape of Industry 4.0 and the transition towards Industry 5.0, manufacturing systems face the challenge of adapting to dynamic, hyper-customized demands. Current Simulation Optimization (SO) systems struggle with the flexibility needed for quick reconfiguration, often requiring time-consuming, resource-intensive efforts to develop custom models. To address this limitation, this study introduces an innovative SO design strategy that integrates three flexible simulation modeling techniques—template-based, structural modeling, and parameterization. The goal of this integrated design strategy is to enable the rapid adaptation of SO systems to diverse production environments without extensive re-engineering. The proposed SO versatility is validated across three manufacturing scenarios (flow shop, job shop, and open shop scheduling) using modified benchmark instances from Taillard’s dataset. The results demonstrate notable effectiveness in optimizing production schedules across these diverse scenarios, enhancing decision-making processes, and reducing SO development efforts. Unlike conventional SO system design, the proposed design framework ensures real-time adaptability, making it highly relevant to the dynamic requirements of Industry 5.0. This strategic integration of flexible modeling techniques supports efficient decision support, minimizes SO development time, and reinforces manufacturing resilience, therefore sustaining competitiveness in modern industrial ecosystems. Full article

In recent years, technologies for human–robot interaction (HRI) have undergone substantial advancements, facilitating more intuitive, secure, and efficient collaborations between humans and machines. This paper presents a decentralized HRI platform, specifically designed for printed circuit board manufacturing. The proposal incorporates many input devices, including gesture recognition via Leap Motion and Tap Strap, and speech recognition. The gesture recognition system achieved an average accuracy of 95.42% and 97.58% for each device, respectively. The speech control system, called Cellya, exhibited a markedly reduced Word Error Rate of 22.22% and a Character Error Rate of 11.90%. Furthermore, a scalable user management framework, the decentralized multimodal control server, employs biometric security to facilitate the efficient handling of multiple users, regulating permissions and control privileges. The platform’s flexibility and real-time responsiveness are achieved through advanced sensor integration and signal processing techniques, which facilitate intelligent decision-making and enable accurate manipulation of manufacturing cells. The results demonstrate the system’s potential to improve operational efficiency and adaptability in smart manufacturing environments. Full article

Brass sheets are extensively utilized in the automotive, electrical, and other industries, where an in-depth understanding of their formability is crucial for achieving optimal performance in production applications. This study investigates the influence of uniaxial pre-strains on the Forming Limit Curve (FLC) of CuZn 70-30 brass sheets, which aims to enhance their formability by identifying and optimizing key forming parameters. Adding a new variable, the impact of uniaxial pre-strain upon FLC, was our aim of this study and, consequently, the CuZn 70-30 brass sheet formability using punch-stretching tests with purpose-built tools, we experimentally obtained FLCs for brass sheets under varying levels of pre-strain (0.04, 0.06, and 0.08) applied through uniaxial tension by using Nakajima tests with purpose-built tools. The objective was to understand how specific factors such as punch parameters, punch corner radius, and strain rate impact the FLC and, consequently, the brass sheets formability. Results indicate a distinct trend of increasing pre-strain levels leading to a significant rise in minor strain capacity along the right portionof the FLC, with a comparatively insignificant effect on the left. This consistent elevation across strain paths suggests improved formability due to pre-straining, highlighting the potential for optimized manufacturing processes and enhanced product quality across industrial applications. Full article

Remarkable mechanical properties make carbon fibres attractive for many industrial applications. However, up to today, carbon fibres come with a significant environmental backpack, undermining their advantages in light of a strong demand for absolute sustainability of new industrial products. Consequently, there is considerable demand for high-quality carbon fibre manufacturing, low waste production, or alternative precursor systems allowing minimization of environmental impacts. Therefore, this paper investigates the capabilities of data analytics with a special emphasis on predictive quality in order to advance the quality management of carbon fibre manufacturing. Although existing research supports the applicability of machine learning in carbon fibre production, there is a notable scarcity of case studies and a lack of a structured repetitive data analytics concept. To address this gap, the study proposes a holistic framework for predictive quality in carbon fibre manufacturing that outlines specific data analytics requirements based on the process properties of carbon fibre production. Additionally, it introduces a systematic method for processing trend data. Finally, a case study of polyacrylonitrile (PAN)-based carbon fibre manufacturing exemplifies the concept, giving indications on feature importance and sensitivity related to the expected fibre properties. Future research can build on the comprehensive overview of predictive quality potentials and its implementation concept by extending the underlying data set and investigating the transfer to alternative precursors. Full article

The development of technology, including in the oil and gas industry, necessitates the creation of materials with special sets of properties, such as high strength characteristics combined with corrosion resistance. One such material is bimetallic pipe, but we are faced with the problem of creating extended structures and obtaining high-quality butt-welded joints of such industrial bimetallic pipes. The microstructure in different parts of the thermomechanically influenced zone of a butt-welded joint of a bimetallic pipe obtained by rotary friction welding (RFW) was investigated by optical and electron microscopy methods. It was established that during rotary friction welding of the bimetallic pipe in standard mode, one metal flowed into the zone of another. This could be explained by the different plastic properties of the steels that made up the bimetal, which must be taken into account in future welding. Standard RFW mode did not result in the formation of a high-quality weld; defects and discontinuities were observed in the joint area. The maximum hardness values were observed directly in the weld joint. It is concluded that rotary friction welding can be used as a welding technology for bimetallic pipes, but the most attention should be paid to the welding mode to obtain a high-quality butt-welded joint. Full article

In 3D printing, the layered structure often results in artifacts. This effect becomes stronger for surfaces with a lower ramp angle. This effect can be mitigated by manufacturing parts with non-planar layers that fit the parts’ surface geometry. Using the open-source slicing software PrusaSlicer. an algorithm was developed to modify the slicer’s input and output data in a way that fits parts with low ramp angle surfaces. To achieve consistent part quality, all layers were modified to be printed in a non-planar way. The test results indicate that the proposed methods can significantly reduce surface roughness. Although the algorithm works well for parts with a flat base and vertical walls, it would need to be highly adapted to work for different part geometries. Additionally, compared to other algorithms used in Curved-Layer Fused Deposition Modeling (CLFDM), the changed layer structure introduces a changed visual appearance of parts. Full article