Search Results (345)

This study investigates the influence of die design parameters on forging forces and thermomechanical responses during near-solidus forging (NSF) of complex steel components. Finite element simulations using Forge NxT analyzed six die configurations varying geometry orientation, gating system design (conical, cylindrical, curvilinear), and draft angles (20° and 30°), with 42CrMo4E steel modeled at 1360 °C. Key responses including punch and lateral forces, temperature distribution, strain localization, and die stress were evaluated to assess design effects. Results showed that the gating system geometry critically controls material flow and load requirements. The conical gating design with a 30° draft angle yielded the lowest punch (141.54 t) and lateral (149.44 t) forces, alongside uniform temperature and strain distributions, which improve product quality by minimizing defects and incomplete filling. Lower lateral forces also reduce die opening risk, enhancing die life. In contrast, the base case with a 20° draft angle exhibited higher forces and uneven strain, increasing die stress and compromising part quality. These findings highlight the importance of selecting appropriate gating systems and draft angles to reduce forming loads, increase die life, and improve uniform material flow, contributing to better understanding of die design in NSF of complex steel components. Full article

Innovative approaches in hot forging, such as the use of floating dies, which aim to minimise burr formation by controlling material flow, require precise management of die geometry distortions. These distortions, primarily caused by thermal gradients, must be tightly controlled to prevent malfunctions during production. This study introduces a comprehensive thermal analysis framework that captures the complete forging cycle—from billet transfer and die closure to forging, spray-cooling, and lubrication. Two advanced heat transfer models were developed: a pressure- and lubrication-dependent contact heat transfer model and a spray-cooling model that simulates fluid dispersion over die surfaces. These models were implemented within the finite element software FORGE-NxT to evaluate the thermal behaviour of dies under realistic operating conditions. These two new models, contact and spray-cooling, implemented within a full-cycle thermal simulation and validated with industrial thermal imaging data, represent a novel contribution. The simulation results showed an average temperature deviation of just 5.8%, demonstrating the predictive reliability of this approach. This validated framework enables accurate estimation of thermal fields in the dies, and offers a practical tool for optimising process parameters, reducing burr formation, and extending die life. Moreover, its structure and methodology can be adapted to various hot forging applications where thermal control is critical to ensuring part quality and process efficiency. Full article

Background/Objectives: Fish eggs activated with UV-irradiated spermatozoa and exposed to the High Hydrostatic Pressure (HHP) shock to inhibit first cell cleavage develop as gynogenetic Doubled Haploids (DHs) that are fully homozygous individuals. Due to the expression of the recessive genes and side effects of the gamete treatment, survival of fish DHs is rather low, and most of the mitotic gynogenotes die before hatching. Nevertheless, as maternal gene products provided during oogenesis control the initial steps of embryonic development in fish, a maternal effect on the survival of gynogenotes needs to be also considered to affect efficiency of gynogenesis. Thus, the objective of this research was to apply an RNA-seq approach to discriminate transcriptional differences between rainbow trout (Oncorhynchus mykiss) eggs with varied abilities to develop after gynogenetic activation. Methods: Gynogenetic development of rainbow trout was induced in eggs originated from eight females. Maternal RNA was isolated and sequenced using RNA-Seq approach. Survival rates of gynogenotes and transcriptome profiles of eggs from different females were compared. Results: RNA-seq analysis revealed substantial transcriptional differences between eggs originated from different females, and a significant correlation between the ability of the eggs for gynogenesis and their transcriptomic profiles was observed. Genes whose expression was altered in eggs with the increased survival of DHs were mostly associated (GO BP) with the following biological processes: development, cell differentiation, cell migration and protein transport. Some of the genes are involved in the oocyte maturation (RASL11b), apoptosis (CASPASE 6, PGAM5) and early embryogenesis, including maternal to zygotic transition (GATA2). Conclusions: Inter-individual variation of the transcription of maternal genes correlated with the competence of eggs for gynogenesis suggest that at least part of the mortality of the rainbow trout DHs appear before activation of zygotic genome and expression of the lethal recessive traits. Full article

Wire electrical discharge machining (WEDM) is a standard micro-manufacturing technology. In WEDM, surface roughness (SR), deviation dimension (DD), and machining time (MT) are critical requirements that impact machining quality and are affected by various input parameters. The workpiece often performs multiple machining steps (roughing, semi-finishing, and finishing) to achieve high accuracy. Each machining step directly affects the accuracy and machining time, and the preceding machining step influences the subsequent machining step parameters. Many input control parameters regulate WEDM’s performance. Thus, optimizing process control parameters at each step is essential to achieve optimal results. This study investigates the influence of input parameters, including pulse on time (Ton), pulse off time (Toff), and servo voltage (SV), on SR, DD, and MT when machining AISI D2 mold steel through rough, semi-finish, and finish cutting. Taguchi and Analysis of Variance (ANOVA) are applied to analyze and optimize this WEDM process. The results display that the optimal surface roughness values for rough, semi-finish, and finish-cut stages are 2.03 µm, 1.77 µm, and 0.57 µm, corresponding to the parameter set of Ton = 6 μs, Toff = 10 μs, and SV = 30 V; Ton = 3 μs, Toff = 15 μs, and SV = 60 V; and Ton = 21 μs, Toff = 45 μs, and SV = 60 V, respectively. In addition, in the finish-cut stage, the parameters for optimal DD of 0.001 mm (0.04%) are Ton = 3 μs, Toff = 15 μs, and SV = 40 V. In contrast, those values for optimal MT of 218 s are Ton = 3 μs, Toff = 30 μs, and SV = 40 V. All optimal input values are confirmed by the manufacturing mold and die parts. Full article

Accurate preform design in forging processes is critical for improving part quality, conserving material, reducing manufacturing costs, and eliminating secondary operations. This paper presents a finite element (FE) simulation-based methodology for preform design aimed at achieving flashless and near-flashless forging. The approach leverages material point backtracking within FE models to generate physics-informed preform geometries that capture complex material flow, die geometry interactions, and thermal gradients. An iterative scheme combining backtracking, surface reconstruction, and point-cloud solid modeling was developed and applied to several three-dimensional forging case studies, including a cross-joint and a three-lobe drive hub. The methodology demonstrated significant reductions in flash formation, particularly in parts that traditionally exhibit severe flash under conventional forging. Beyond supporting the development of new flashless forging sequences, the method also offers a framework for modifying preforms during production to minimize waste and for diagnosing preform defects linked to variability in frictional conditions, die temperatures, or material properties. Future integration of the proposed method with design of experiments (DOE) and surrogate modeling techniques could further enhance its applicability by optimizing preform designs within a localized design space. The findings suggest that this approach provides a practical and powerful tool for advancing both new and existing forging production lines toward higher efficiency and sustainability. Full article

The topographical, microstructural, and mechanical surface properties of additively manufactured components depend on variations of several processing parameters. Most studies focus on a narrow range of parameter variations, with the surface and subsurface characteristics being determined for that limited set of conditions. This makes it difficult to optimize these properties for additively manufactured parts and the energy consumption of the additive-manufacturing (AM) process. Our study looks at the systematic variation of two key AM parameters over their full range using a commercial AM machine. The laser scanning speed (500–1700 mm/s) and the laser power (250–370 W) were the parameters used. We analyze and discuss how these two parameters affect the surface topography, roughness, porosity, microstructure and hardness, as well as their anisotropy for the top and side surfaces during powder bed fusion, using a single AM machine and printing strategy. The aluminum alloy AlSi10Mg was selected for the study. It is one of the most commonly used materials in die casting and has the potential to take advantage of AM technology, since these parts can be lightweight, have good mechanical properties and to be produced with complex shapes. Full article

In the stamping process of automotive parts, springback is a major problem when using Advanced High-Strength Steel (AHSS). This phenomenon significantly impacts the shape accuracy of products and is difficult to control. This study aims to optimize process parameters such as blank holder force (BHF), die clearance, and blank width to minimize springback in the workpiece. Using optimal process parameters will enhance the efficiency of die compensation processes. The study uses the Finite Element Method (FEM) simulation to predict forming behavior. The case study, Reinforcement-CTR PLR, is made from AHSS grade JSC980Y with a thickness of 1 mm. Four material model combinations were evaluated against actual experiment results to select the most accurate springback prediction model. A full factorial design was used for experiments with varied process parameters. The optimization process used regression and various Artificial Neural Networks (ANNs). From the result, a Deep Neural Network (DNN) with two hidden layers performed with the highest accuracy compared to the other models. The optimal process parameters were identified as 27.62 tons BHF, 1 mm die clearance, and a 290 mm blank width. These optimal results achieved 98.05% of the part area within a displacement tolerance of −1 to 1 mm, closely matching FEM-based validation. Full article

Aluminum foam is expected to be a leading candidate for lightweight parts due to its light weight and excellent shock-absorption and sound-absorption properties. In order to use it as a part, it is essential to form it into the desired shape. However, the cell walls that form the pores are composed of thin aluminum. When aluminum foam is formed, the cell walls easily fracture and the pores collapse. This results in the loss of the properties of the aluminum foam. Past studies have shown that press forming aluminum foam immediately after foaming, while it is still in the softened state, prevents cell wall failure and pore deformation. In this study, we attempted to perform a continuous process from the foaming of the precursor to the press forming of aluminum foam for three precursors, for the purpose of the continuous production of aluminum foam with desired shapes. It was shown that it is possible to continuously and sequentially foam the precursors by heating and press forming the foamed samples. In addition, aluminum foam with a similar shape, porosity, and pore structure can be fabricated using the continuous process. Also, it was shown that aluminum foam with complex shapes can also be continuously fabricated by using a complex-shaped die. Furthermore, it was indicated that the use of a die in press forming can shorten the cooling time and reduce the production time. Full article

The metal thickness uniformity of the micro-electroforming process determines the structural accuracy, surface finish, and functional characteristics, which directly affect the quality, performance, and reliability of the final parts. However, due to the non-uniformity of the electric field distribution, the problem of thickness non-uniformity in the micro-electroforming process has always been one of the key challenges limiting its application and development. The auxiliary cathode structure can improve the uniformity of electroforming thickness by regulating the cathode electrodeposition rate and electric field distribution and is widely used in the micro-electroforming process. In this study, with the micro-array metal die core as the research object, based on finite element simulations, the effect of the geometrical parameters of the auxiliary cathode on the thickness uniformity of electroforming is analyzed in depth. This study introduces the optimization method of the BP neural network and the NSWOA (Non-dominated Sorting Whale Optimization Algorithm) and achieves a significant improvement in the unevenness of electroforming thickness by designing and adjusting the parameters of the position, width, and shape of the auxiliary cathode. The unevenness of the microarray metal mold core is reduced to 4% from 475% without the auxiliary cathode, using the auxiliary cathode structure designed with this method. Full article

This paper proposes a novel tube hydro-joining process, which combines piercing, hole flanging, and nut inlaying. The nut punch shape design proposed by this paper can deliver three advantages of no scrap, no oil leakage, and longer flange length, which can achieve stronger clamping force and accordingly increase the pull out load. First, we use the finite element analysis to investigate the elasto-plastic deformation of the aluminum alloy A6063 tube during the hydro-joining process. A punch-shaped nut with a tapered locking part is designed to increase the elasto-binding strength of the pierced tube and the pull out load of the inlayed nut. The effects of hydro-joining loading paths on the formability of the A6063 tubes and punch-shaped nuts are examined. Additionally, the effects of fit zone size, nut punch stroke length, internal pressure, nut diameter, and the die hole diameter on the pull out load and twisting torque are explored. Finally, experiments on hydro-joining of A6063 tubes are conducted to validate the finite element modeling and the simulation results. Full article

The high-pressure die-casting (HPDC) process involves injecting molten light metal into a steel mold under high pressure, resulting in parts with excellent surface quality and precise dimensions. However, this process subjects the mold to thermal fatigue and mechanical stress, which can lead to damage over time. This study investigated the wear characteristics of two types of inserts made from different steel materials, SKD61 steel and FDAC steel, under HPDC conditions. A thorough approach that combined computer simulations, experiments, and 3D scanning was employed to analyze wear patterns and dimensional changes after up to 300 casting cycles. The results indicate that the SKD61 steel outperformed the FDAC steel in terms of wear resistance and dimensional stability. The maximum deposition values of the SKD61 mold were only 0.009 mm, which was only 25% compared to the FDAC mold, indicating a significantly higher wear resistance. These findings are crucial for selecting and enhancing insert materials in HPDC, ultimately leading to higher-quality and more efficient casting. Full article

Automotive manufacturers are changing their product models faster due to the customization of users’ demands. In response, suppliers must react by improving the flexibility of their means of production and making the changeover process more efficient and agile to avoid monetary losses. This article reports a prototype that uses computer vision, deep learning algorithms, and mathematical methods to derive the spatial position (x, y, z) of features of the machined parts of high-pressure die-casting (HPDC) aluminum products. It uses an RGB-D sensor to capture and process an image with the you only look once (YOLO) algorithm to determine the center of specific workpiece features. With this information, the feature depth of each center is obtained from the depth matrix and then introduced into a polynomial regression formula to acquire the spatial position (x, y, z) in millimeters. The prototype is a complementary tool for quickly sampling workpieces in the production line and verifying that they meet the requirements and specifications of spatial distances among features. With this evidence, only if necessary, the piece is sent for further and comprehensive measurement by a coordinate-measuring machine (CMM), in line with the accuracy demanded by the automotive industry. Full article

Cu-based alloys and composites are popular to prepare electroconductive parts. However, their processing can be challenging, especially in case of composites strengthened with oxides. To save the necessary time and costs, numerical simulations can be of help when determining the deformation behaviour of (newly introduced) materials. The study presents a combined method of strengthening of Cu by adding 5 wt.% of La₂O₃ particles and performing shear-based deformation by equal channel angular pressing (ECAP). The effects of the method on the microstructure, mechanical properties, and thermal stability of the composite are examined both numerically and experimentally. The results showed that the La₂O₃ addition caused the maximum imposed strain to be higher for the composite than for commercially pure Cu, which led to the development of subgrains and shear bands within the microstructure, and a consequent increase in microhardness. The numerical predictions revealed that the observed differences could be explained by the differences in the material plastic flow (comparing the composite to commercially pure Cu). The work hardening supported by the addition of La₂O₃ led to a significant increase in stress and punch load during processing, as well as contributed to a slight increase in deformation temperature in the main deformation zone of the ECAP die. Certain inhomogeneity of the parameters of interest across the processed workpiece was observed. Nevertheless, such inhomogeneity is typical for the ECAP process and steps prospectively leading to its elimination are proposed. Full article

The honey bee (Apis mellifera) is of paramount importance to human activities through the pollination services they provide in agricultural settings. Honey bee colonies in the United States have suffered from an increased rate of annual die-off in recent years, stemming from a complex set of interacting stressors that remain poorly described. Defining the cellular responses that are perturbed by divergent stressors represents a key step in understanding these synergies. We found that multiple model stressors induce upregulated expression of the lactate dehydrogenase (Ldh) gene in the midgut of the eusocial honey bee and that the Ldh gene family is expanded in diverse bee species. Alterations in Ldh expression were concomitant with changes in the expression of other genes involved in cellular respiration and genes encoding insulin/insulin-like growth factor signaling (IIS) pathway components. Additionally, changes in metabolites in the midgut after stress, including increased levels of lactate, linked metabolic changes with the observed changes in gene expression. Select transcriptional changes in response to stress were similarly observed in the solitary alfalfa leafcutting bee (Megachile rotundata). Thus, increased Ldh expression may be part of a core stress response remodeling cellular respiration and insulin signaling. These findings suggest that a conserved cellular response that regulates metabolic demands under diverse stressful conditions may play a protective role in bees regardless of life history. Full article

In this study, laser oscillation welding was utilized to offer an effective solution for the joint welding of heat-treatment-free die-cast aluminum alloys, which expands the practical applications of automotive structural parts and heat sinks for electronic devices. The effects of oscillation amplitude on the macro-morphology, microstructure, and properties of the alloy weld were examined, and a molten pool flow model was developed to compare the behavior of the molten pool with and without oscillation. The results show that increasing the oscillation amplitude eliminates the coarse Al₁₅(Fe,Mn)₃Si₂ phase, resulting in a finer and more uniform distribution of the eutectic Si and Mg₂Si phases. At an oscillation amplitude of 7 mm, the maximum tensile shear load and displacement were 2761 N and 1.17 mm, respectively. Laser oscillation was found to enhance the fluidity of the molten pool, reduce porosity, improve weld quality, and effectively decrease cracks and inhomogeneous grain distribution. These findings provide a research basis for optimizing the laser oscillation welding process and for the practical welding of fabricated devices. Full article