Search Results (73)

This study investigates the melt-flow behavior of the AlSi₉Cu₃ alloy during high-pressure die casting using a combined experimental and numerical approach. A transparent die and a high-speed camera were used to capture the transient motion of the melt front, while a validated computational model reproduced the filling dynamics under identical boundary conditions. The influence of the gating-system geometry—particularly the gate thickness, flow-path length, and inlet cross-section—was analyzed with respect to filling velocity, filling time, and flow stability. To quantify hydraulic losses that arise in practical die-casting conditions, an empirical correction coefficient k₂ was introduced. Its value was obtained by regression analysis based on ten repeated measurements of filling time for each configuration. The deviation between the simulated and experimental velocities did not exceed 5%, demonstrating the reliability of the numerical model within the tested parameter range. The results show that the optimized gating design reduces flow instability, suppresses air entrapment zones, and yields a more uniform velocity distribution across the cavity. The empirical relations derived involving k₂ provide a practical tool for preliminary design of gating systems, enabling faster optimization without extensive trial-and-error procedures. The methodology presented in this work offers a validated basis for improving gating-system performance in high-pressure die casting of aluminum alloys. Full article

Acquiring reliable thermal data during the high-pressure die-casting (HPDC) process remains a significant challenge due to its complexity and rapidly evolving thermal environment. In industrial settings, the influence of process parameters is typically evaluated after solidification by examining the final casting quality, as direct temperature measurements within the die during operation are difficult to obtain. Additionally, most casting simulation tools lack accurate correlations for the interfacial heat transfer coefficient (IHTC) as a function of process parameters. To address this limitation, a laboratory-scale hot chamber die-casting (HCDC) apparatus was developed to replicate the fluid flow and the thermal conditions of industrial HPDC operation while enabling direct thermal measurements inside the die cavity using embedded thermocouples. The molten metal temperature was estimated using the lumped capacitance method, and the IHTC was determined through a custom inverse heat conduction algorithm incorporating an adaptive forward time-stepping scheme. This algorithm was validated by solving the forward heat conduction problem using the ANSYS 2025 R1 Transient Thermal solver. The experimentally obtained IHTC values showed good agreement with those measured during industrial HPDC trials, with a maximum deviation of about 14% in the peak value, while the full width at half maximum (FWHM) differed by less than 12%. These results confirm that the developed HCDC setup can reliably reproduce industrial thermal conditions and generate high-quality thermal data that can be used in numerical casting simulations. Full article

To address incomplete die filling, high cracking tendency, and severe die wear in the conventional forging of AISI-410 martensitic stainless steel U-shaped forgings, an optimized billet volume pre-allocation strategy was proposed. Two improved forging schemes for the U-shaped forgings were designed: the Arc Concave Flattening Scheme (adding arc-shaped concave features to the flattening die for corner volume compensation) and Preformed Volume Allocation Scheme (incorporating a preforming step for strategic volume pre-allocation at ends and corners). Finite Element Analysis employing the Oyane damage model and Archard wear model was employed to simulate and optimize the forging process. The optimal scheme was applied to production trials. The results demonstrated that the Preformed Volume Allocation Scheme significantly improved the geometric compatibility between the billets and the final forging die cavity. As a result, the billet’s temperature, strain, and equivalent stress uniformity increased, reducing cracking tendency. Moreover, the rise in the mitigated temperature and stress concentration resulted in reduced final forging die wear. Production trials confirmed a qualified rate of ~96% (34% higher than the Original Scheme). The final forging die service life reached 300 pieces per refurbishment cycle, showing a 50% improvement. This work provides theoretical and practical guidance for optimizing the forging processes of complex martensitic stainless steel components. Full article

Superplastic materials are characterised by extreme lightness and remarkable ductility. Instead of a punch, a gas is used to push the sheet into the die cavity, and it is precisely regulated to control the material’s strain rate. Forming a superplastic material while maintaining a high strain rate sensitivity index requires the forming gas to follow a precise pressure–time loading curve. This can be excellently predicted with the aid of the finite element method (FEM). Therefore, for the superplastic material to exhibit its best formability throughout the entire process, it is necessary to control the strain rate step by step to keep the maximum strain rate within the material’s optimal superplastic range. In this work, the results of a superplastic-forming process used to create a hemispherical shell are presented. This was carried out using both a circular blank of uniform thickness and a blank with a conical cross-section. The analysis was performed using finite element modelling. Specifically, the results obtained using 3D analysis were compared with those obtained using axisymmetric analysis for conditions of axial symmetry. Using the conical cross-section blank helped achieve a more uniform thickness distribution in the produced hemispherical shell. The success of the numerical activity was validated through results from appropriate experimental work conducted on the magnesium alloy AZ31. The results show that, by employing a blank characterised by a conical section profile, the thickness distribution appears more uniform than that of a constant-thickness blank. Full article

In this paper, dedicated material models were developed and verified for three melts of EN AW-7021 alloy, differing in zinc and magnesium content, for tube extrusion conditions. Based on the plastometric tests, it was found that in the studied range of strain parameters, the analyzed melts of the same aluminum alloy showed different sensitivity to strain rate and temperature. In addition, a significant effect of magnesium and zinc content on the plasticity of the tested material was observed. Therefore, dedicated material models describing stress changes were developed for each melt analyzed. The models were then implemented into the material database of the QForm-Extrusion^® program, which was used for the theoretical analysis of the industrial extrusion process. In order to verify the results of numerical calculations, industrial tests of the extrusion process were carried out. The force parameters and the rate of the extrusion process were mainly analyzed. The use of dedicated material models for each melt contributed to the accuracy of numerical modeling. A high degree of compliance was obtained regarding the theoretical and experimental extrusion force and the velocity of metal flowing out of the die cavity, among others. Full article

Eccentric camshaft components serve as critical elements in emergency pump systems for commercial vehicle steering mechanisms. To optimize material utilization efficiency, reduce production costs, and enhance manufacturing throughput, this investigation implemented a vertical upsetting extrusion forming methodology for camshaft forging production. Initial trials revealed defect formation in forged components. By analyzing the causes of the defects, an improved process method was developed to eliminate them. The chemical composition, macroscopic and microscopic morphologies of defects, forging process, and metal streamlines were analyzed and studied by means of a direct reading spectrometer, high-resolution camera, metallographic microscope, DEFORM finite element analysis software, and chemical etching. Findings indicate that the observed defects constitute forging-induced cracks, with subsequent normalizing heat treatment exacerbating decarburization phenomena in defect-adjacent microstructures. During the forging process of the forgings, the metal continuously extruded into the die cavity, and the inflowing metal pulled the dead zone metal downward, causing the flow lines aligned with the contour to bend into S-shaped metal streamlines. Cracks formed when the tensile stress in the dead zone metal exceeded the material’s critical tensile stress. An improved process was proposed: adopting a vertical upsetting extrusion forming method with a 40° diversion angle at the junction between the first step and the thin rod in the die cavity. Numerical simulations confirmed complete elimination of deformation dead zones in the optimized process. Experimental verification demonstrated crack-free forgings. Therefore, the eccentric camshafts formed by the initial process exhibited forging cracks, and the proposed improved method of vertical upsetting extrusion forming with a diversion angle effectively eliminated the forging cracks. Full article

Tracking the microstructural evolution during high-pressure die casting of Al-Si alloys is challenging due to the rapid solidification, varying thermal conditions, and severe turbulence. The process involves a transition from slower cooling in the shot sleeve to rapid cooling in the die cavity, resulting in a bimodal dendritic microstructure and nucleation of new finer dendrite arms on fragmented externally solidified crystals. In this study, a two-dimensional phase-field model was employed to investigate the solidification behaviour of a hypoeutectic Al-7% Si alloy during high-pressure die casting. The model is based on thermodynamic formulations that account for temperature changes due to phase transformation heat, thermal boundary conditions, and solute diffusion in both liquid and solid phases. To replicate the observed bimodal microstructure, solid–liquid interface properties such as thickness, energy, and mobility were systematically varied to reflect the transition from the shot sleeve to the die cavity. The results demonstrated the model’s ability to capture the growth of dendrites under shot sleeve conditions and nucleation and development of new dendrite arms under the rapid cooling conditions of the die cavity. Full article

Traditional methods for wrinkled tubes involve welding processes and additional elements, such as plates, screws, rivets, and guides. Considering all the limitations of these processes, this work aims to propose a methodology that allows for maximising the manufacturing process of carbon steel tube joints with seaming using cold forming and minimising the cost of the final product. Therefore, the present work aims to develop a computational model, based on the finite element method, to optimise the deformation process of T6 Aluminium tubes (ø 45 × ø 38.6 mm) with a length of 120 mm. The method uses a steel die with cavities to achieve wrinkled tubes by a forming process. This numerical study was carried out using the Ansys^® 2022 R2 software. A nonlinear material and an incremental structural analysis were used. The applied methodology allowed the optimisation of process parameters, the application of forces during tube deformation, the geometry of the die cavity, boundary conditions, and mesh discretisation. Numerical modelling was carried out using the axial symmetry of the assembly (tube–die), enabling a simplified and efficient execution of the final tube geometry. The results were analysed based on the maximum pressure applied to the tube, and the vertical and horizontal displacements of the deformed component, thus obtaining the tube flow with complete filling inside the die cavity at the end of deformation. The die geometry that produced the best results presented a cavity with a radius of curvature of 3 mm, 6 mm in height, and with a depth of 4 mm. The optimised result of the die geometry generated satisfactory results, with the displacement on the x-axis of the tube of approximately 2.85 mm, ensuring the filling of the cavity at the end of the process. For this, the maximum pressure exerted on the tube was approximately 374 MPa. Full article

To meet the in-orbit construction needs of super-large spacecraft for ultra-long rod structures, this paper proposes an innovative on-orbit roll forming method for polyetheretherketone (PEEK)-based rod stock. This method ingeniously integrates temperature gradient control into a continuous deformation surface cavity design to achieve an efficient forming of resin rod components. A parametric model of the forming die cavity was established based on the comprehensive bending and downhill methods, and the boundary conditions for the temperature distribution gradient within the cavity were determined. Through the simulation and analysis of the PEEK rod curling and stitching forming process, the influence of the cavity configuration parameters on the forming load was determined. By constructing a test platform for the roll forming characteristics of resin rod components, the effects of different forming methods, stitching temperatures, and feed rates on forming quality and load were verified, and the main factors affecting the width of the welding zone, the roundness of the rod, and the straightness of the weld were analyzed. Experimental results show that the proposed continuous roll forming scheme can achieve an efficient and continuous forming of resin rod structures. When the length of the member is processed to 300 mm, at a formed rod diameter of 20 mm, by employing a cavity deformation zone length of 210 mm, a cavity clearance of 0.1 mm, a sheet width of 61 mm, a feed rate of 1 mm/s, and a sealing zone temperature setting of 335 °C, optimal rod forming quality can be achieved, characterized by a straightness error of 0.0133 ± 0.005 mm and a roundness error of 0.19 ± 0.07 mm. The proposal of this scheme provides a reliable basis for the continuous manufacturing of rod structures in the on-orbit construction of large space structures in terms of both the scheme and the parameter selection. Full article

Electrical erosion molding (EDM) is an unconventional machining technology widely used in the manufacture of injection molds for plastics injection molding for the creation of complex cavities and geometries. However, EDM productivity can be challenging, directly influencing mold manufacturing time and cost. This work aims to improve EDM productivity in the context of mold manufacturing for plastics injection molding. The research focuses on the optimization of processing parameters and strategies to reduce manufacturing time and increase process efficiency. Through a rigorous experimental approach, this work demonstrates that the optimization of EDM parameters and strategies can lead to significant productivity gains in the manufacture of plastic injection molds without compromising part quality and accuracy. This research involved a series of controlled experiments on a Mitsubishi EA28V Advance die-sinking EDM machine. Different combinations of pre-cutting parameters and processing strategies were investigated using copper electrodes on a heat-treated steel plate. Productivity was evaluated by measuring the volume of material removed, and geometrical accuracy was checked on a coordinate measuring machine. The experimental results showed a significant increase in productivity (up to 61%) by using the “processing speed priority” function of the EDM machine, with minimal impact on geometric accuracy. Furthermore, the optimized parameters led to an average reduction of 12% in dimensional deviations, indicating improved geometric accuracy of the machined parts. This paper also provides practical recommendations on the selection of optimal EDM processing parameters and strategies, depending on the specific requirements of plastic injection mold manufacturing. Full article

Aluminum alloy die casting has achieved rapid development in recent years and has been widely used in all walks of life. However, due to its high pressure and high-speed technological characteristics, avoiding hole defects has become a problem of great significance in aluminum alloy die casting production. In this paper, the filling visualization dynamic characterization experiment was innovatively developed, which can directly study and analyze the influence of different injection rates on the formation and evolution of alloy flow patterns and gas-induced defects. As the injection speed increased from 1.0 m/s to 1.5 m/s, the average porosity increased from 7.49% to 9.57%, marking an increase in the number and size of the pores. According to the comparison with Anycasting, simulation results show that a liquid metal injection speed of 1.5 m/s when filling the flow front vs. the previous injection rate of 1.0 m/s caused fractures when filling at the same filling distance. Therefore, the degree of the broken splash at the flow front is more serious. Combined with the analysis of transport mechanics, the fracturing is due to the wall-attached jet effect of the liquid metal in the filling process. It is difficult for the liquid metal to adhere to the type wall in order to fuse with subsequent liquid metal to form cavity defects. With an increase in injection velocity, the microgroup volume formed via liquid breakage decreases; thus the volume of air entrapment increases, finally leading to an increase in cavity defects. Full article

Against the backdrop of climate policy goals and the EU’s aim for a resource-efficient economy, the foundry industry must rethink product range, energy consumption, and production technologies. Light metal casting, which is performed through processes like gravity die casting and high-pressure die casting, requires effective thermal management, which is crucial for optimising mould filling, solidification, cycle times, and part quality. Against this background, this study presents the development and characterisation of a cooling system that completely dispenses with energy-intensive heating/cooling devices. The system is based on a mask shape combined with internal spray cooling. This paper shows the simulation workflow for developing the mould mask and the design of the cooling system and compares the performance with conventional temperature control using channels. In the tests, an 82% higher cooling rate was achieved with Cool-Spray than with conventional temperature control, which was approx. 2.5 mm below the cavity surface. In addition to the more dynamic temperature control, the potential for process control was utilised, and the component quality of the test part was significantly improved compared to conventional temperature control. Full article

This research addresses and resolves current challenges in meshless Lagrangian methods for simulating viscoelastic materials. A split-step scheme, or pressure Poisson reformulation of the Navier–Stokes equations, is introduced for incompressible viscoelastic flows in a Lagrangian context. The Lagrangian differencing dynamics (LDD) method, which is a thoroughly validated Lagrangian method for Newtonian and non-Newtonian incompressible flows, is extended to solve the introduced split-step scheme to simulate viscoelastic flows based on the Oldroyd-B constitutive model. To validate and evaluate the new method’s capabilities, the following benchmarks were used: lid-driven cavity flow, droplet impact response, 4:1 planar sudden contraction, and die swelling. These findings highlight the LDD method’s effectiveness in accurately simulating viscoelastic flows and capturing large deformations and memory effects. Even though the extra stress was directly modeled without any regularization approach, the method produced stable simulations for high Weissenberg numbers. The stability and performance of the the Lagrangian numerics for complex temporal evolution of material properties and stress responses encourage its use for industrial problems dealing with polymers. Full article

Currently, the field of microgear manufacturing faces various processing challenges, particularly in terms of size reduction; these challenges increase the complexity and costs of manufacturing. In this study, a technique for microgear manufacturing is aimed at reducing subsequent processing steps and enhancing material utilization. This technique involves the use of trough dies with extrusion-cutting processing, which enables workpieces to undergo forming in a negative clearance state, thus reducing subsequent processing time for micro products. We conducted finite element simulations using microgear dies, measuring stress, velocity, and flow during the forming process of four types of dies-flat, internal-trough, external-trough, and double-trough dies. The results indicated that the buffering effect of the troughs reduced the rate of increase in the material’s internal stress. In the cavity, the material experiences a significant increase in hydrostatic pressure, leading to the formation of a “hydrostatic pressure wall”. This pressure barrier imposes substantial constraints on the flow of the material during dynamic processes, making it difficult for the material to move into the remaining areas. This effectively enhances the blockage of material flow, demonstrating the critical role of hydrostatic pressure in controlling material distribution and movement. In addition, combining the characteristics of both into a double-trough die enhances the overall stability of forming velocity, reduces forming load and energy consumption, and maximizes material utilization. Results further revealed that microgears manufactured using double-trough dies exhibited defect-free surfaces, with a dimensional error of less than 5 μm and tolerances ranging from IT5 to IT6. Overall, this study offers new insights into the traditional field of microgear manufacturing, highlighting potential solutions for the challenges encountered in current microstamping processes. Full article

Laser cladding technology is an effective surface modification technique. In order to prepare coating with excellent properties on the surface of the cold heading die punch, stellite-6 cladding coating with different proportions of Y₂O₃ was prepared on the surface of W6Mo5Cr4V2 high-speed steel using laser cladding technology in this paper. The effects of different Y₂O₃ contents on the macroscopic morphology, microstructure, phase analysis, microhardness, and tribological properties of the stellite-6 coatings were investigated. It was determined that the optimal Y₂O₃ content for the stellite-6 powder was 2%. The results showed that the coating with 2%Y₂O₃ had the least number of pores and cracks and exhibited good surface flatness when joined. The microstructure became finer and denser, composed mainly of branch, cellular, equiaxed, and columnar grains. The coating consisted mainly of γ-Co, Fe-Cr, and Co₃Fe₇ strengthening phases, indicating good metallurgical bonding between the coating and the substrate. The average microhardness reached 539 HV when 2%Y₂O₃ was added, a 15.2% increase compared with the unmodified multilayer coating. The friction coefficient of the clad layer was 0.356, a 21.8% improvement over the unmodified stellite-6 coating. The average worn area of the cross-section was 3398.35 μm², a reduction of approximately 27.8% compared with the unmodified stellite-6 clad layer. The wear surface primarily exhibited abrasive wear, with fewer cavities and a smoother surface. Full article