Sheet Metal Research Articles

Miniaturized meandered ring graphene-metal metasurface with wide angle control on the transmitted wave

In this paper, a miniaturized transmissive metasurface using graphene-metal in the 3.5 THz frequency range is proposed and designed to control the wavefront of the transmitted wave. The designed unit cell has four identical ultra-thin layers. Each layer contains a meandered ring-shaped slot carved in a metal sheet, which is partially filled with four graphene patches in symmetrical places. By employing the meandered shape slots, the lateral dimensions of the unit cells are reduced to 0.19 of the free space wavelength, which, to the best of our knowledge, is the most miniaturized designed structure among the existing transmissive metasurfaces in the literature. Full wave simulations confirmed that without any physical changes and by just altering the spatial distribution of the chemical potential of the graphene patches, wave-front control is achieved. The achievements include beam steering and beam splitting with numerous discrete angles up to 63° and beam focusing with optional focal lengths. It is envisaged that besides 6G wireless telecommunications, this structure could also be beneficial for THz imaging, nano-photonic and opto-electronic devices.

Effect of Water Injection Systems on Sheet Metal Bending by Nanosecond Green Laser Peen Forming

Effect of Water Injection Systems on Sheet Metal Bending by Nanosecond Green Laser Peen Forming

Exploring alternative manufacturing techniques for high-quality solar cell interconnectors: a comparative study of laser cutting and electric discharge machining

Abstract Solar cell interconnectors are typically crafted from thin foils to establish an electrical connection between two components. For limited production of interconnectors with non-standard dimensions, common production methods (such as stamping and sheet metal processes) cannot be utilized. This article examines alternative techniques, such as Fiber Laser Cutting Machine and Electric Discharge Machining (wire cutting). The laser cutting method did not achieve the desired quality standards, leading to the rejection of the interconnectors. Issues such as burning, local melting, and damage to the silver coating were noted at the edges. The melting of the coating layers formed brittle intermetallic compounds, which can cause cracking and reduce weldability and solderability. In contrast, the Electric Discharge Machining method successfully produces interconnectors with complex shapes by stacking layers of foil. This approach results in high-quality interconnectors that showed no signs of burning or local melting on their edges.

On the control of thickness in gas blow metal sheet forming processes: A review

Although the advantages of formability are notable, blow-forming processes, which are classified as sheet metal stretching processes, present limits in terms of uniformity of the thicknesses of the produced product. This is a review paper that collects the numerical and experimental studies of the literature on the new metal sheet forming techniques to improve formability and production efficiency. In particular, the focus is on (a) the multi-phase forming technique and (b) the techniques involving a blank with a profile of variable initial thickness. These techniques promote a strategic decrease of the thickness in some areas of the part to be formed to improve the final distribution of thicknesses in those most critical areas of the component to be made. The paper presents the finite element modelling works of the literature to predict the accuracy of a formed part in terms of the uniformity of its thickness that avoids breakups; thus, allowing to design and establish the feasibility of new forming techniques. The parameters influencing the forming processes were analysed by comparing the results of the finite element simulations in terms of the thickness distribution of the finished product and forming times. This paper presents also the experimental forming tests that verified these forming techniques and provided a thickness profile that reduces maximum thinning and forming times in comparison with the traditional processes. The conclusion of the paper demonstrates that these forming techniques allow to obtain a more uniform thickness of the formed part in a shorter processing time.

A Simple Pump-Free Approach to Generating High-Throughput Microdroplets Using Oscillating Microcone Arrays

Droplet generation is crucial in various scientific and industrial fields, such as drug delivery, diagnostics, and inkjet printing. While microfluidic platforms enable precise droplet formation, traditional methods often require costly and complex setups, limiting their accessibility. This study introduces a simple, low-cost approach using an off-the-shelf unit and a 3D-printed reservoir. The device, equipped with a driver board, piezo-ring transducer, and a metal sheet with holes, generates oil-in-water (O/W) droplets with an average diameter of 4.62 ± 0.67 µm without external fluid pumps. Its simplicity, cost-effectiveness, and scalability make it highly suitable for both lab-on-chip and industrial applications, demonstrating the feasibility of large-scale uniform droplet production.

Investigation into the sheet metal forming process using solid granules medium with graphite powder addition

ABSTRACT The solid granules medium sheet metal forming process uses loose particles instead of a rigid convex mold in the deep drawing process. This study focused on a mixed medium of solid granules with added graphite powder , establishing numerical models for four different proportions of graphite powder-solid granules mixtures. A finite element simulation of deep drawing was conducted using 08AL sheets. A deep drawing test shows that the thickness distribution curve closely aligns with the numerical simulation. By adding graphite powder to the solid granules medium, the lubrication conditions between the granules and the sheet metal can be modified, increasing the thickness in the fracture-prone areas of the cylindrical part. Utilizing this numerical model yields thickness distribution and deformation characteristics that closely resemble those observed in deep drawing tests, thereby contributing significantly to the optimization and advancement of this forming technology.

Investigation of activation energy of Maxwell fluid with Newtonian heat effect at the boundary layer flow on a cylinder embedded in porous medium

AbstractThis study aims to investigate the flow of Maxwell fluid over a cylinder, considering the combined effect of Magnetohydrodynamics (MHD) and a permeable medium on the equation of momentum, heat generation and radiation on the equation of energy, and activation energy on the mass equation. The objective is to analyze the impression of these physical phenomena on the fluid's behavior under specified boundary conditions, with a focus on the Newtonian heating effect. The significance of this research lies in its application to industrial processes, polymer extrusion and cooling of metallic sheets, where controlling fluid flow and energy transfer is crucial. The dimensional governing equations for momentum, energy, and concentration were changed into non‐dimensional forms via appropriate dimensionless quantities and similarity variables. The subsequent nonlinear ordinary differential equations were answered using the BPV4C inbuilt MATLAB solver. The key findings reveal that the concentration outline rises with a rise in activation energy and declines with a rise in the chemical reaction. Additionally, the Nusselt number profile displays an increasing trend with the Newtonian heating parameter, indicating enhanced heat transfer. Quantitative results demonstrate that the occurrence of a porous medium and MHD significantly impacts the velocity and temperature contours. The real‐time application of this study can be seen in the optimization and design of chemical reactors, heat exchangers, and cooling systems in engineering processes. The developed model delivers insights into controlling energy and mass transfer in processes involving stretching surfaces, which is essential for improving efficiency and product excellence in various industrial applications.

Numerical and Experimental Research of the Plastic Forming Process of Hastelloy X Alloy Sheets Using Elastomeric and Steel Tools

The results of experimental and numerical studies of plastic forming of sheets made of the difficult-to-deform Hastelloy X, a nickel-based alloy with a thickness of 1 mm, using layered elastomeric punches and steel dies, are presented in this publication. The elastomeric punches were characterized by hardness in the range of 50–90 Shore A, while the dies were made of 90MnCrV8 steel with a hardness of over 60 HRC. The principle of operating the stamping die was based on the Guerin method. The finite-element-based numerical modeling of the forming process for various configurations of polyurethane inserts was also carried out. The results obtained from numerical modeling were confirmed by the results of experimental tests. The drawpieces obtained through sheet forming were subjected to geometry tests using optical 3D scanning. The results confirmed that in the case of forming difficult-to-deform Hastelloy X, Ni-based alloy sheets, the hardness of the polyurethane inserts significantly affected the geometric quality of the obtained drawpieces. Significant nonuniform sheet metal deformations were also found, which may pose a problem in the process of designing forming tools and the technology of the plastic forming of Hastelloy X, Ni-based alloy sheets.

Optimisation of Flexible Forming Processes Using Multilayer Perceptron Artificial Neural Networks and Genetic Algorithms: A Generalised Approach for Advanced High-Strength Steels

Flexibility is crucial in forming processes as it allows the production of different product shapes without changing equipment or tooling. Single-point incremental forming (SPIF) provides this flexibility, but often results in excessive sheet metal thinning. To solve this problem, a pre-forming phase can be introduced to ensure a more uniform thickness distribution. This study represents advances in this field by developing a generalised approach that uses a multilayer perceptron artificial neural network (MLP ANN) to predict thinning results from the input parameters and employs a genetic algorithm (GA) to optimise these parameters. This study specifically addresses advanced high-strength steels (AHSSs) and provides insights into their formability and the optimisation of the forming process. The results demonstrate the effectiveness of the proposed method in minimising sheet metal thinning and represent a significant advance in flexible forming technologies applicable to a wide range of materials and industrial applications.

Reducing the diameter of the atomized particles by coating polymer membrane on the inner wall of micro-tapered holes of the ultrasonic mesh atomizers

Atomized inhalation therapy with its rapid efficacy, low side effects and high medicine utilization, has become a crucial method for treating respiratory diseases. The depth of atomized particles deposition in the respiratory tract mainly depends on the particle diameter, making the reducing of the atomized particle size crucial for medicine deposit in lung. In the existing literatures, for the widely used dynamic mesh atomizer, the majority of the researches focused on the mechanical structure and the vibration characteristics of the atomizers. However, there is little researches on the micro-tapered holes of the metal sheet of the atomizer, despite the fact that the diameter of these tapered holes determines the size of the atomized particles. Due to the processing technology, the diameter of the micro-tapered holes cannot be further reduced, which greatly limits the development of the dynamic mesh atomizer in inhalation therapy. In this study, we consider the use of polymer coating on the inner wall of the micro-tapered holes to eliminate burrs, reduce the diameter of the holes, and ultimately reduce the size of the atomized particles. A theoretical model of the initial thickness of the coating polymer membrane and the rupture depth under the uniform air pressure applied to a single tapered hole was established. The metal sheets with different initial coating thicknesses were processed to verify the theoretical model by observing the quality of the inner surface and measuring the diameter of the holes. The particle size measurement experiment results show that when the initial coating thickness was 3 μm and 4.5 μm, the average particle sizes were reduced by 12.5 % and 23.2 %, respectively. Therefore, the proposed method can effectively reduce the atomized particles size, which helps to efficiently deposit atomized drugs in the lungs.

Investigation of roll forming process and quality control factors for metal bipolar plates

Metal bipolar plates (BPPs) are crucial components of proton exchange membrane fuel cells (PEMFCs), with the quality of their formation affects the power generation efficiency and lifespan of the fuel cells. The predominant manufacturing method, stamping, often results in localized excessive stretching of metal BPPs, thereby limiting the depth of the flow channels. Roll forming, dominated by bending deformation, is a forming process that ensures uniform thinning and greater depth of BPPs. The multi-directional flow channel roll forming model for BPPs is constructed in this paper for the first time, the characteristics of the roll forming process is investigated. Effects of process parameters on the forming results are discussed. The investigation indicates that during the roll forming process, the channel ports and corners are critical areas where defects are most likely to occur. The average filling ratio of the longitudinal flow channels is 5.6% higher than that of the transverse flow channels. The plastic strain in the longitudinal flow channels is about 36% higher than in the transverse ones, which making the form is more difficult to form, but the thickness is more uniform. Increasing the diameter of the rollers can enhance the filling ratio and flatness, but it will exacerbate thinning at the corners of the flow channels. When the ratio of the flow channel width to the rib width is close to 1, the filling ratio of the BPP is higher, with less thinning, resulting in a better forming result. As the depth of the flow channel increases, resulting in a thinner BPP, when depth-to-width ratio exceeding 0.6 is more likely to lead to failure. Increasing the speed of roll forming can lead to a greater thinning of the BPP and may even cause it to crack. The thinner the sheet metal is, the higher the filling ratio of the BPP and the more uniform its thickness. Those results can provide technical references for the structural design and forming process optimization of BPPs.

Instance Segmentation XXL-CT Challenge of a Historic Airplane

Instance segmentation of compound objects in XXL-CT imagery poses a unique challenge in non-destructive testing. This complexity arises from the lack of known reference segmentation labels, limited applicable segmentation tools, as well as partially degraded image quality. To asses recent advancements in the field of machine learning-based image segmentation, the ‘Instance Segmentation XXL-CT Challenge of a Historic Airplane’ was conducted. The challenge aimed to explore automatic or interactive instance segmentation methods for an efficient delineation of the different aircraft components, such as screws, rivets, metal sheets or pressure tubes. We report the organization and outcome of this challenge and describe the capabilities and limitations of the submitted segmentation methods.

Material characterization of forged bronzes from ancient China (c. 11th-2nd century BCE) reveals development of the non-mainstream metalworking technique in Chinese bronze production

Although ceramic piece-mould casting was the dominant metalworking technique in the Chinese Bronze Age (c. 2100-221 BCE), the forging technique was also employed by craftsmen to pursue lightweight bronzes with thin walls and high hardness. However, compared to the ceramic piece-mould casting technique, research on forging technology is relatively limited. In this research, 48 sheet metal fragments of Chinese bronzes from different regions and periods (from the Zhou to Han dynasties) across China were analyzed by metallography, SEM-EDS, and hardness testing. The results show that craftsmen had a profound understanding of copper alloy properties and were able to produce thin-walled, functional artifacts by forging cast blanks with appropriate alloy compositions. With the development of forging technology and political changes, the types of forged thin-walled bronzes became more diverse, and their consumers expanded from the elite to civilians. This study not only reveals the material characterization of forged bronzes, but also elucidates the historical trajectories of forging technology and the multifaceted interplay between cultural influence, aesthetic pursuits and technological advancement in the development of forging techniques in ancient China.

Material efficiency at the component level: how much metal can we do without?

Global production of steel and aluminium is a major driver of greenhouse gas emissions. Various processes might allow continued primary production of the two metals, but all depend on emissions-free electricity or carbon storage, and global capacity of these two key resources will be below demand for decades to come. As a result, zero-emissions steel and aluminium will mainly come from recycling, but supply will be lower than demand. This motivates demand reduction, and for the first time, this article estimates the inefficiency in current metal use by component type. The results demonstrate that around 80% of steel and 90% of aluminium liquid metal produced today may be unnecessary. Around 40% of liquid steel and 60% of liquid aluminium are never used in final components as they are removed along the supply chain of manufacturing. Of the metal that enters final service, approximately one-third could be saved by avoiding component over-specification. A further third could be saved, where the properties of metal are not used to their limits. These results point to specific opportunities for innovation in design and manufacturing technology, of which the highest priority is to re-think the use of sheet metal in construction.This article is part of the discussion meeting issue 'Sustainable metals: science and systems'.

Numerical and Experimental Analysis of Roller Hemming on Door Panel’s Curved and Straight-Edge of Flat Plane

Owing to its enhanced production efficiency, roller hemming has become the mainstream process for forming and joining metal sheets in the automotive industry. This study investigates the roller hemming process of a specific car door panel through a combination of experimental analysis and finite element analysis (FEA) on both straight-edge and curved-edge flat surfaces. Consequently, the mechanical properties of the door panel, including tensile strength, yield strength, modulus of elasticity, and Poisson’s ratio, were estimated through tensile testing and then underwent finite element modeling. The simulation results demonstrated the varying distribution of stress during the rolling hemming process, with the highest stress concentration observed in the bending area. Additionally, creepage and growing results were acquired from both simulation and experimental data to validate the precision of the numerical model. A comparison was made between the experimental and simulation results of the external forces exerted by the roller on the panel. In both straight- and curved-edge sections, the external force during final hemming exceeded that during pre-hemming, as revealed by experimental measurements of both normal and tangential external forces, surpassing their corresponding simulated values.

A Comprehensive Review on the Incremental Sheet Forming of Polycarbonate.

Incremental sheet forming has emerged as an excellent alternative to other material forming procedures, incrementally deforming flat metal sheets into complex three-dimensional profiles. The main characteristics of this process are its versatility and cost-effectiveness; additionally, it allows for greater formability compared to conventional sheet forming processes. Recently, its application has been extended to polymers and composites. The following review aims to present the current state of the art in the incremental sheet forming of polycarbonate, an outstanding engineering plastic, beginning with initial studies on the feasibility of this process for polymers. Attention is given to the advantages, drawbacks, and main applications of incrementally formed polycarbonate sheets, as well as the influence of process parameters and toolpath strategies on features such as formability, forming forces, deformation and failure mechanisms, geometric accuracy, surface quality, etc. Additionally, new hybrid forming methods for process optimisation are presented. Finally, a discussion is provided on the technical challenges and future research directions for incremental sheet forming of polycarbonate and, more generally, thermoplastics. Thus, this review aims to offer an extensive overview of the incremental forming of polycarbonate sheets, useful to both academic and industrial researchers working on this topic.

Compound Die for manufacturing of Plain Washer from sheet metal scrap

Compound Die for manufacturing of Plain Washer from sheet metal scrap

Nanoscale roughness to mitigate polydimethylsiloxane (PDMS) sticking in liquid crystal display (LCD) vat photopolymerization (VPP): Separation force reduction without losing resolution

Liquid crystal display (LCD) vat photopolymerization (VPP) is gaining attention among polymer-based additive manufacturing (AM) processes due to its high accuracy, superior surface finish, and cost-efficiency. However, one of the main challenges is the high layer separation force, which is heavily influenced by the flexibility of the interface. Sticking between polydimethylsiloxane (PDMS) and the LCD panel reduces flexibility, shifting the separation behavior from Johnson-Kendall-Roberts (JKR) to Derjaguin-Muller-Toporov (DMT)-like behavior. This study presents a novel approach to mitigate PDMS sticking by introducing nanoscale surface roughness. Sandblasted sheet metals with varying sand mesh sizes were used as molds to create interfaces with different roughness levels. The findings reveal that a surface roughness of 0.262 µm significantly reduces PDMS sticking, making the interface more flexible. The optimized flexible interface (SP 2000) interface reduced the separation force 50-fold compared to unmodified PDMS while maintaining high print resolution. Case studies involving rigid and flexible photopolymer resins further emphasize the effectiveness of the SP 2000 interface in addressing PDMS sticking issues. This research highlights the critical role of interface flexibility and presents a promising solution for improving LCD VPP performance.

AUTOMATIC PATH PROGRAMMING FOR THE MANUFACTURING OF SHEET METAL COMPONENTS USING INCREMENTAL FORMING TECHNOLOGY

Asymmetric Incremental Sheet Forming (AISF) is an unconventional forming technology that involves localized and progressive plastic deformation of a sheet using a tool, typically a punch, following a continuous and numerically controlled path. Due to its specific characteristics and advantages, such as flexibility and relatively low implementation cost, it is considered a technology with great potential for competitively producing small series of sheet metal components. However, there are still some challenges, such as the lack of specific CAM tools for this technology, which has hindered its industrialization. Although the process may appear simple, with a 3D path sufficient to transform the original flat sheet into the final part, it has been observed that the manufacturing of real designs requires extensive knowledge of the technology to choose the appropriate path based on the target geometry. In this regard, this study presents a new solution developed by Tecnalia that incorporates expert process knowledge and enables automatic programming of Incremental Forming paths. Specifically, the solution allows programming paths aimed at manufacturing different geometric features commonly found in sheet metal components. This development has been validated through the manufacturing of several parts in a robotic cell implemented at Southeast University in Nanjing.

Process and mechanism of gradient structural pure copper sheets prepared by extrusion machining

Due to the balanced strength-plasticity, gradient structural (GS) materials have received much attention in recent years. Extrusion machining (EM), a new severe plastic deformation, can prepare GS metal sheets in one step. However, studies on the forming mechanism and mechanical properties of GS plates prepared by EM are insufficient, and there is a gap in their microstructure evolution and thermal stability. Combining numerical simulation and experiments, the GS pure copper sheets prepared under different extrusion thicknesses t ch were systematically investigated. The results showed that the prepared sheets exhibited significant gradient distributions in equivalent strain, grain size, and hardness, which could be adjusted by varying t ch. As t ch increased, the material strength decreased, and the elongation tended to increase. Moreover, the increased t ch contributed to a higher lateral extrusion machining ratio. From the coarse-grained layer to fine-grained layer, the grain orientation tended to be randomized. When the annealing temperature exceeded 250°C, the gradient structure gradually disappeared, and the hardness greatly decreased. Upon annealing at 350°C, the tensile strength and elongation approximated the initial annealed samples. Accordingly, the GS sheets prepared by EM possessed better properties and provided relevant guidance to improve the theory and application of related processes.