Metal Stamping Research Articles

Precision-induced localized molten liquid metal stamps for damage-free transfer printing of ultrathin membranes and 3D objects

Transfer printing, a crucial technique for heterogeneous integration, has gained attention for enabling unconventional layouts and high-performance electronic systems. Elastomer stamps are typically used for transfer printing, where localized heating for elastomer stamp can effectively control the transfer process. A key challenge is the potential damage to ultrathin membranes from the contact force of elastic stamps, especially with fragile inorganic nanomembranes. Herein, we present a precision-induced localized molten technique that employs either laser-induced transient heating or hotplate-induced directional heating to precisely melt solid gallium (Ga). By leveraging the fluidity of localized molten Ga, which provides gentle contact force and exceptional conformal adaptability, this technique avoids damage to fragile thin films and improves operational reliability compared to fully liquefied Ga stamps. Furthermore, the phase transition of Ga provides a reversible adhesion with high adhesion switchability. Once solidified, the Ga stamp hardens and securely adheres to the micro/nano-membrane during the pick-up process. The solidified stamp also exhibits the capability to maneuver arbitrarily shaped objects by generating a substantial grip force through the interlocking effects. Such a robust, damage-free, simply operable protocol illustrates its promising capabilities in transfer printing diverse ultrathin membranes and objects on complex surfaces for developing high-performance unconventional electronics.

Re-manufacturing of Pre-deformed Automotive Sheet Metal Stamping Scrap Without Melting

Abstract The recycling of aluminium sheet metal typically involves shredding and re-melting, processes which are both energy-intensive and challenged by the presence of metallic contaminants. To mitigate these issues, this study explores an alternative approach: the re-manufacturing of deep-drawn parts directly from scrap aluminium sheets, thus bypassing the melting step. We used 2 mm thick Al-Mg sheet metal in H111 temper to produce simulated stamping scrap (miniaturized bonnets). Blanks were cut from these bonnets and secondary parts in a cross-cup geometry were deep-drawn using two different forming processes: warm-forming at 200 °C and O-temper forming at room temperature. The resulting maximum draw depths were 20-22 mm for warm-forming and 25-30 mm for O-temper forming. While warm-forming resulted in lower draw depths, O-temper forming led to coarse recrystallized grain formation in some regions. Our approach could significantly reduce the energy consumption associated with aluminium recycling.

Research on stamping formability and process simulation of AZ31 magnesium alloy based on deep learning

To study the formability of AZ31 magnesium alloy under different temperature conditions and improve the forming quality of its parts, this paper aims to solve the minimization problem of pursuing the “maximum thinning rate”. This study obtained the mechanical properties of AZ31 magnesium alloy at 25 °C, 150 °C, 250 °C, and 350 °C through uniaxial tensile tests and explored the stamping formability of AZ31 magnesium alloy mobile phone cases using the finite element inverse calculation method (MSTEP). Based on the hot stamping of AZ31 magnesium alloy at 250 °C, the Monte Carlo Simulation (MCS) method was used to randomly sample the blank holder force, stamping speed, friction coefficient, and resistance coefficient, and then simulate to obtain the corresponding “maximum thinning rate”. In addition, a hybrid prediction model optimized by Genetic Algorithm (GA) and Dung Beetle Optimization (DBO) based on the Back Propagation Neural Network (BPNN) - Random Forest (RF) was used to explore the nonlinear relationship between blank holder force, stamping speed, friction coefficient, resistance coefficient, and the “maximum thinning rate”. The results show that the plasticity of AZ31 magnesium alloy enhances with the temperature increase, especially exhibiting the best stamping formability at 250 °C. Feature importance indicates that the resistance coefficient and stamping speed have a greater impact on the maximum thinning rate, while the influence of blank holder force and friction coefficient is relatively smaller. Mean Square Error (MSE) shows that the predictive capability of the hybrid model is significantly superior to that of the single BP neural network and Random Forest model, displaying optimal efficiency. The predicted maximum thinning rate by the model is 15.39 %, with an error rate of only 0.32 % compared to the DYNAFORM finite element software simulation results, confirming the correctness, accuracy, and effectiveness of the prediction model. Overall, this study provides practical optimization strategies for metal stamping forming processes, with significant practical application value.

Antenna array of waveguide horns with an E-plane aperture, as well as horns with an aperture in the E- and H-planes

Background. Currently, in connection with the conduct of a special military operation, the issue of the availability of inexpensive mobile terminals for high-speed satellite communications of domestic production is very relevant, as well as due to the large extent of the territories of our country, there are a number of areas where cellular communication is absent, for example, the Taiga, the Arctic, the territory of the Arctic Ocean, etc. Therefore, the only possible connection in these territories is satellite communication. Aim. Development of a linear equidistant antenna array with equal amplitude and common-mode excitation for a mobile satellite communication terminal. Methods. The antenna array was designed from the open ends of waveguides with a cross section of 19 × 11 mm with air filling. Adjacent pairs of radiating waveguides are powered by an E-planar divider: the waveguide is divided in half in height by a thin metal diaphragm, wave reflections from which are insignificant; further, in each half of the power divider, height-separated right and left turns and smooth transitions in the E-plane are implemented – an extension from 5,25 mm to 11 mm. Results. An antenna array with a period of 19,5 mm has been developed. Overall dimensions: opening width – 624 mm, height – 12 mm, depth – 118 mm. A feature of the antenna array design is the use of smooth asymmetric transitions in the E-plane according to the exponential law; in the opening of the headlights, waveguide asymmetric horns alternate, with a period equal to 4 values of the width of the waveguides, taking into account the width of their narrow walls, expanding in the upper (2 adjacent radiators) and lower (next 2 radiators) directions. Conclusion. The advantage of using an approach to the construction of linear antenna arrays powered by multichannel power dividers is the ability to minimize the depth of the antenna system. The main disadvantages are the constructive and technological complexity of power dividers and significant power losses with a large number of channels. Possible manufacturing technologies of the developed phased array: 1. Stamping of polystyrene of the inner part of the power divider and emitters. Next, polishing, copper spraying and electroplating with a layer of copper. 2. Printing on a 3D polystyrene printer, polishing, copper spraying and copper electroplating. 3. Manufacture of a power divider using SIW technology based on standard microwave laminates. The use of metallized through holes for matching power dividers. Antenna elements and coaxial waveguide junctions are made by stamping from polystyrene, or printing on a 3D printer from polystyrene, then polishing, spraying a layer of copper and electroplating with a layer of copper. 4. Metal stamping of the power divider, emitters and coaxial waveguide junctions (2 parts). The dielectric insert can be printed on a 3D printer made of polystyrene.

Real-time detection of surface cracking defects for large-sized stamped parts

This study presents a framework for the real-time detection of surface cracking in large-sized stamped metal parts. The framework aims to address the challenges of low detection efficiency and high error rates associated with manual cracking detection. Within this framework, a novel network, SNF-YOLOv8, is proposed to efficiently detect cracking while ensuring that the detection speed matches the production speed. The network incorporates a convolutional spatial-to-depth module to enhance the detection of small-sized cracking and mitigate surface interference during inspections. Furthermore, a visual self-attention mechanism is introduced to improve feature extraction. A combination of standard convolutional and depth-wise separable convolutional layers in the neck network enhances speed without compromising accuracy. Experimental validation conducted using a dataset from actual production lines, in collaboration with a multi-national corporation, demonstrates that SNF-YOLOv8 achieves an average precision of 85.2% at a detection speed of 164 frames per second. The framework achieves an accuracy rate of 98.8% in detecting large-sized cracking and 96.4% in detecting small-sized cracking, meeting the requirements for high-precision and real-time detection applications.

A generalisable tool path planning strategy for free-form sheet metal stamping through deep reinforcement and supervised learning

AbstractDue to the high cost of specially customised presses and dies and the advance of machine learning technology, there is some emerging research attempting free-form sheet metal stamping processes which use several common tools to produce products of various shapes. However, tool path planning strategies for the free forming process, such as reinforcement learning technique, derived from previous path planning experience are not generalisable for an arbitrary new sheet metal workpiece. Thus, in this paper, a generalisable tool path planning strategy is proposed for the first time to realise the tool path prediction for an arbitrary sheet metal part in 2-D space with no metal forming knowledge in prior, through deep reinforcement (implemented with 2 heuristics) and supervised learning technologies. Conferred by deep learning, the tool path planning process is corroborated to have self-learning characteristics. This method has been instantiated and verified by a successful application to a case study, of which the workpiece shape deformed by the predicted tool path has been compared with its target shape. The proposed method significantly improves the generalisation of tool path planning of free-form sheet metal stamping process, compared to strategies using pure reinforcement learning technologies. The successful instantiation of this method also implies the potential of the development of intelligent free-form sheet metal stamping process.

Combining physics-based and data-driven methods in metal stamping

Combining physics-based and data-driven methods in metal stamping

ВАРІАНТИ ВИКОРИСТАННЯ ВЛАСТИВОСТІ УНІФІКАЦІЇ ПРИ ВИБОРІ КОНСТРУКТИВНО-ТЕХНОЛОГІЧНИХ РІШЕНЬ З’ЄДНАНЬ “МЕТАЛ+КОМПОЗИТ”

Possibility of unification property realization in application to variants of structural-technological solutions of “metal+composite” joints.It is drawn that this property is important for up-today vehicle engineering structures at different goals of its manufacturing. It is shown that there are three possible options can be revealed in metal-composite heterogenous joints realization: with monolithic, cylindrical and sheet transversal fastening connections.Possibility of application sheet transversal fastening elements produced on metal strips is considered exactly. Also, possibility of implementation strips of different materials and thickness is analyzed.The property of unification is most fully manifested at the stages of design, technological preparation of production and production itself. Variants of technological processes for manufacturing sheet fasteners on metal strips using stamping methods or laser cutting are proposed. An analysis of the advantages and disadvantages of these technical processes showed that the most rational method is stamping with bending.Options for route technical processes for forming transversal connections on metal tips using sheet reinforcing elements are proposed.Options for equipment are proposed, with the help of which serial production of teeth on metal strips is possible. It should be noted among these equipment options metal stamps for stamping teeth and using an electro-hydraulic device for bending them.Examples of implementation of design and technological solutions with sheet micro-elements in the manufacture of high-pressure vessels and in the strengthening of bolted joints are given.

Analysis and optimization of stamping and forming process of bearing outer ring

To address the common issues of wrinkling, tearing, and uneven wall thickness in the actual sheet metal stamping process of the outer ring of needle roller bearings, this study analyzes critical technical indicators such as forming limits, thickness distribution, and principal strains in the forming process in detail. Three-dimensional models of the concave and convex dies were constructed. The effects of different process parameters, including stamping speed, edge pressure, sheet metal thickness, and friction coefficient, on the quality of the forming parts were investigated by varying these parameters. Subsequently, the orthogonal experimental method was used to determine an optimal experimental group from multiple sets of experiments. It was found that under the process parameters of a stamping speed of 3000 mm/s, edge pressure of 2000 N, sheet metal thickness of 0.9 mm, and friction coefficient of 0.125, the forming quality of the outer ring of the bearing is ideal.

Deep Learning Approach for automatic detection of split defects on sheet metal stamping parts

Sheet metal stamping processes are used primarily for high-volume products produced for a range of sectors, from white goods manufacturing to the automotive and aerospace sectors. However, the process is susceptible to defects. Due to the numerous potential defects that may arise in the stamping product, human inspectors are often deployed for their detection. However, they are unreliable and expensive, especially when operating at production speeds equivalent to the stamping rate. This study investigate CNN-based automatic inspection for stamping defects. The study carried out two sets of experiments. All the Experiments yielded high classification accuracy, recall and precision demonstrating the viability of the CNN method for defect detection in the sheet metal stamping process. Additionally, this study revealed that in limited data confounding factors can be a challenge. The second experiment further explored the impact of small neck defects, harsh lighting and reflections on defect detection. The observations indicated that the model struggled to identify defects occluded by reflections, particularly small neck defects.

The effect of hyaluronic acid and iodine complex gel compared to Vaseline on deep second‐degree burn wound in rats

AbstractThe combination of hyaluronic acid and iodine (Hyodine) has sparked interest in wound care and could have valuable applications in treating burn injuries. We aimed to provide valuable insight into the potential advantages, limitations, and implications of using Hyodine in burn wound management. We studied 25 male rats to assess the clinical outcomes and wound‐healing effects of Hyodine. Each rat received a deep second‐degree burn wound on their back using metal stamps. Subsequently, the rats were then randomly split into two groups. The first group was treated with a layer of Hyodine gel, while the second group received Vaseline. The burn sites were photographed on days 1, 7, 14, and 21 using a digital camera. After excision of the burn wounds, histopathology slides were stained and evaluated in terms of the degree of epithelialization, angiogenesis, inflammatory cells' infiltration, and collagen amount and arrangement. Despite a non‐significant difference regarding the extent of burn wound area between intervention and control groups in the first day of experiment, the rats that were treated with Vaseline showed a significant decrease compared to those who received Hyodine in the second and third weeks (p = 0.02). On the other hand, epithelialization, pathology score, and collagen synthesis were significantly different between days 7, 14, and 21 of each group. However, collagen arrangement and neovascularization were only significantly different between days 7, 14, and 21 in Hyodine group (p = 0.02 and p = 0.03, respectively). The Hyodine gel may offer beneficial outcomes in patients with a burn wound. Based on our findings, despite a non‐significant difference in the extent of burn wound area, using Hyodine revealed a significant improvement in different histopathological variables including neovascularization, and collagen arrangement.

A stable diffusion enhanced YOLOV5 model for metal stamped part defect detection based on improved network structure

Machine-vision-based defect detection for large metal stamping is a fundamental requirement for improving product quality and inspection speed. However, the performance of machine vision in detecting defects is limited by the large variety of stamped products, significant dimensional differences, and long data-acquisition cycles. To overcome these problems, metal stamping detection has been achieved using the improved YOLOV5 model, which features a slim neck and a multiheaded self-attentive mechanism for detecting wrinkles, holes, and cracks in metal stamping. An image-processing module was used to reduce the impact of metal reflections and improve image quality. Stable diffusion improvement was used to augment the dataset to overcome the small dataset size problem and enhance its generalisation capability. In addition, a BotNet structure with a self-attentive mechanism was introduced into the YOLOV5 model backbone to improve the image feature extraction capability. We then optimised the prediction head structure of YOLOV5 to improve the detection speed and accuracy. Ablation experiments were performed to analyse and verify the effectiveness of each module. The results of the ablation experiments show that the mAP of our proposed stable diffusion improvement data enhancement method, and the YOLO-Bot-VOV algorithm, for metal stamped part defect detection reached 98.2 %, and the parameters were reduced by 0.432 million.

Contribution to the formability improvement in sheet metal stamping by a novel technique to control press kinetics

The thickness variation during sheet deep drawing process has an impact on the quality of the final product and can lead to local material fractures. To minimize this phenomenon caused by varying degrees of stretching in different areas of the sheet, various methods can be employed. This research paper introduces a novel technique for metal sheet deep drawing, specifically designed for parts with complex geometric shapes that exhibit significant variations in deformation levels across different areas. The objective of this method is to enhance the quality of the deep drawing process by reducing thickness variations in the final part. In this proposed approach, the vertical movement of the punch is accomplished through two vertical rotational movements. This increases the flexibility of the deformation process, ensuring that the active tools elements occupy the most advantageous positions determined by the material flow in the die. As a result, the material's deformability is improved, allowing for a higher degree of deformation. Additionally, this new method offers a relatively simple design and kinematics solutions for the press and eliminates the need for lengthy assembly-disassembly times.

Formation of reflective shells by electric arc spraying and application of composite material to the punch

In the course of the work, the process of forming reflective shells and finding the position of grid elements after deformation was investigated. Fixation of mesh nodes by electric arc spraying. After that, a composite material such as polystyrene is applied to form reflective shells. Minimization of potential energy is carried out numerically by an iterative method. The result of the work is the formation of the antenna array shell by the method of electric arc spraying and the application of the composite material. The following forming operations of sheet metal stamping are known: drawing, rotary drawing, relief forming, trimming, including rubber and liquid drawing, hydromechanical drawing, explosion drawing, electric discharge stamping, electromagnetic stamping, hydropneumatic drawing, which allow to obtain a shell from sheet material (solid or gas and water permeable) by pressing it against a die or punch with a transfer medium.

Testing the effects of photobiomodulation on angiogenesis in a newly established CAM burn wound model

Burn wounds are a common challenge for medical professionals. Current burn wound models hold several limitations, including a lack of comparability due to the heterogeneity of wounds and differences in individual wound healing. Hence, there is a need for reproducible in vivo models. In this study, we established a new burn wound model using the chorioallantoic membrane assay (CAM) as a surrogate model for animal experiments. The new experimental setup was tested by investigating the effects of the auspicious biophysical therapy, photobiomodulation (PBM), on the wound healing of an induced CAM burn wound with a metal stamp. PBM has been shown to positively influence wound healing through vascular proliferative effects and the increased secretion of chemotactic substances. The easily accessible burn wounds can be treated with various therapies. The model enables the analysis of ingrowing blood vessels (angiogenesis) and diameter and area of the wounds. The established model was used to test the effects of PBM on burn wound healing. PBM promoted angiogenesis in burn wounds on day 4 (p = 0.005). Furthermore, there was a not significant trend toward a higher number of vessels for day 6 (p = 0.065) in the irradiated group. Changes in diameter (p = 0.129) and the burn area (p = 0.131) were not significant. Our results suggest that CAM can be a suitable model for studying burn wounds. The novel experimental design enables reproducible and comparable studies on burn wound treatment.

Numerical analysis of maximum force in deep drawing processes of prismatic parts

The high competitiveness of the industrial sector and the short time for developing new products drives the use of process analysis tools that enable speeding up the design phase. In sheet metal stamping projects, numerical simulation has become indispensable. As a replacement for traditional trial-and-error methods, the finite element method (FEM) enables the optimization of process-related variables. Consequently, it is possible to mitigate some of its main problems, such as the emergence of fracture, wrinkling, and springback. A second alternative for analyzing the process, even faster and cheaper, is based on the use of analytical calculations. These can predict, among other parameters, the forces involved in stamping. This study aims to evaluate the degree of accuracy of equations predicted in the literature to estimate the maximum stamping force of non-axisymmetric parts. For this purpose, analytical results of the stamping force of 1 mm thick austenitic stainless steel AISI 304 sheets were compared to results obtained via numerical simulation.

Statistical analysis of stoppages in a metal stamping line: Case study

Purpose: This article seeks to establish a statistical analysis to estimate the time of stoppages in a stamping line, which have a high variability that generates an unreliable scenario for the production program. Likewise, this document shows the methodological sequence to carry out a statistical analysis in a case study at an industrial level, considering variables of a real scenario.Design/methodology/approach: The methodological sequence is divided into five stages. Initially, the information of the stamping process was collected, later the types of stoppage were categorized according to the characteristics of the process. A collection of historical data information on stoppage times was carried out. With the information collected, the percentage frequency of occurrence of stops due to tool changes and incidents in the process was determined, and they were characterized by a Weibull distribution. Finally, to verify the effectiveness of the downtime behavior, a model was developed to simulate the availability of the stamping line in the Vensim Ple ® program.Findings: The model showed that the frequency analysis and the Weibull distribution obtained a similar behavior to reality. The study verified that it is necessary to establish a categorization of the characteristics of the downtimes, according to the characteristics of the pieces produced to evaluate the information, in this way, the times of change by tooling were established through a frequency of use and the stoppages by additional incidences to the process were better.Research limitations/implications: The basis for this study is the reliability of the information, especially in the data record. It has the disadvantage that the bias of the analyst is present when the information is recorded and analyzed.Practical implications: The methodology presented in this article is a reference for industrial applications in which it is required to establish improvement scenarios based on the reduction of stoppages present in the production lines.Originality/value: The importance of this study is that it was possible to establish a suitable workload allocation in the presses to optimize production.

Industrial Application of Surface Crack Detection in Sheet Metal Stamping Using Shift-and-Add Speckle Imaging

Industrial Application of Surface Crack Detection in Sheet Metal Stamping Using Shift-and-Add Speckle Imaging

Improving shape formation under conditions of plane tensile stress

Thin-walled axisymmetric truncated parts made of sheet billets are actively used in rocket and aerospace engineering. Improvement to their shape formation, based on directed material thickness change will ensure the production of parts with minimum thickness variation. This will also enable aviation and space industry enterprises to attain leading positions, as well as reduce labor costs. This work studies the possibility of obtaining thin-walled axisymmetric parts of truncated tapered shape using one of the methods of sheet metal stamping under flat tensile stress conditions (flanging). The mechanism was identified and the analysis of the stress-strain state of the billet during deformation was carried out. This takes into account the minimizing of the difference between the specified and technologically possible thicknesses. A mathematical model was developed to consider the shaping method based on the process of flanging. Theoretical studies were based on the principles of the plastic deformation theory of sheet materials. This was achieved by the following factors: approximate differential equations of force equilibrium; equations of constraint; plasticity conditions; and fundamental constitutive relations under given initial and boundary conditions. The process of flanging was simulated using the LS-DYNA software package with the following initial data of a conical billet made of 12Kh18N10T steel: cone angle 16.4°, thickness Sbillet = 0.3 mm. The aim was to eliminate errors in designing a tool for future implementation of the method on a manufactured die tooling, as well as to confirm the theoretical conclusions on the selection of technological parameters and achieve minimal thickness variation. The steps of computer modeling are presented, indicating the main process parameters such as material model, mechanical characteristics of the workpiece material, type of elements, kinematic loads, conditions of contact interaction of elements with each other, etc.

Analisis Beban Kerja dan Jumlah Pekerja Menggunakan Metode Workload Analysis (Studi Kasus: PT. Metal Stamping)

PT. Metal Stamping is a company engaged in Metal Processing that produces motorcycle parts, filters & radiator parts which in the production process of course use the power of the workers. This can cause an overload of workload experienced by production operators in the Production Department 2. In an effort to solve this problem in this study using the Workload Analysis method, namely with the aim of being able to find out the amount of physical workload experienced by the operator and analyze the optimal number of production operators in the AIDA 250, AIDA 2500, Komatsu 2000 and AIDA 15 machines in the Production Department 2 section. The results showed that there was still an excess workload experienced by operators where the highest physical workload was experienced by operators working on AIDA 15 machines by 118.11%. With the results showing that there is still an excess physical workload experienced by the operators, it is estimated that it is necessary to hold overtime hours for operators because the excess workload is not too large and is considered to be still manageable in the presence of overtime hours.