Browse Topic: Stamping
Dangling from a weather balloon 80,000 feet above New Mexico, a pair of antennas sticks out from a Styrofoam cooler. From that height, the blackness of space presses against Earth’s blue skies. But the antennas are not captivated by the breathtaking view. Instead, they listen for signals that could make air travel safer.
Climate-neutral aviation requires resource-efficient composite manufacturing technologies and solutions for the reuse of carbon fibers (CF). In this context, thermoplastic composites (TPC) can make a strong contribution. Thermoforming of TPC is an efficient and established process for aerospace components. Its efficiency could be further increased by integration of joining processes, which would otherwise be separate processes requiring additional time and equipment. In this work, an integrative two-step thermoforming process for hollow box structures is presented. The starting point are two organosheets, i.e. fiber-reinforced thermoplastic sheets. First, one of the organosheets, intended for the bottom skin of the uplift structure, is thermoformed. After cooling, the press opens, the organosheet remains in the press and an infrared heater is pivoted in, to locally heat up just the joining area. Meanwhile, a second organosheet, intended for the top skin, is heated and thermoformed and simultaneously joined to the lower skin, thereby forming the box structure. The process can be referred to as co-consolidation with localized heating of the joining areas. The target of this study was to initially built up a test setup allowing to process single lap shear samples with this concept, test the shear strength (tensile test based on DIN 1465) and compare it with similar tests on samples joined via co-consolidation and resistance welding. The tests were based on organosheets processed from nonwovens made of polyamide 6 fibers and recycled carbon fiber. Resistance welding and co-consolidation gave similar shear strength of about 9 MPa, but the co-consolidation with localized heating reached only around 56 % of the shear strength (around 5.4 MPa). Optical observation shows adhesive failure, indicating that the contact time above temperatures allowing for healing was insufficient and requires further improvement.
The initial powder used for the manufacturing of NdFeB permanent magnets is usually prepared through rapid cooling, either by melt spinning or strip casting. The powders produced by these two methods are suitable for different applications: while melt-spun powder is a good initial material for bonded and hot-deformed magnets, strip-cast powder is normally used for sintered magnets. To investigate the suitability of using strip-cast powder to manufacture hot-deformed magnets, NdFeB powder prepared by strip casting was hot pressed (without particle alignment) and compared with melt-spun powder prepared under the same conditions (700 °C, 45 MPa, 90 min). Although the processing parameters are the same (pressed in the same mold), the magnetic properties of the magnets made from the two powders are significantly different. Surprisingly, the magnet made from the strip-cast powder (after ball milling) shows comparable magnetic properties to those of isotropic magnets, with coercivity (HcJ) of 1270 kA/m and remanence (Br) of 0.7 T, while that made from the melt-spun powder exhibits much lower properties: HcJ = 480 kA/m, Br = 0.5 T, although the melt-spun powder initially shows much better magnetic properties than the strip-cast powder. Possible reasons for such a difference in magnetic properties are discussed. It was shown that the particle size of the initial powder plays an important role in determining the final magnetic properties of the hot-pressed magnets.
The photochemical etching (PCE) process is distinguished by its capacity to fabricate metal parts with unparalleled accuracy. This process sidesteps the typical stresses and deformations linked to conventional metal-working, like stamping or laser cutting, which can compromise material integrity. Such fidelity is crucial in the manufacture of components for thermal management systems, where material integrity and component precision are non-negotiable for ensuring effective heat creation or dissipation. PCE’s ability to craft parts with smooth, burr-free edges and exact dimensions means heat management components work more effectively, bolstering the reliability and extending the service life of micro electronic devices.
Multiple experimental studies were performed on galling intiation for variety of tooling materials, coatings and surface treatments, sheet materials with various surface textures and lubrication. Majority of studies were performed for small number of samples in laboratory conditions. In this paper, the methodology of screening experiment using different combinations of tooling configurations and sheet material in the lab followed by the high volume small scale U-bend performed in the progressive die on the mechanical press is discussed. The experimental study was performed to understand the effect of the interface between the sheet metal and the die surface on sheet metal flow during stamping operations. Aluminum sheet AA5754 2.5mm thick was used in this experimentation. The sheet was tested in laboratory conditions by pulling between two flat insert with controllable clamping force and through the drawbead system with variable radii of the female bead. Comparing pulling forces during sheet metal flow through the testing setup provides information on flow resistance along the interface between the sheet and the tool surfaces. Onset of galling can be detected by the growth of the pulling force. In addition, it is defined by measurement of the surface of the tool and the scratches on the surface of the samples. Typical galling is seen as lines of sheet material deposit on the surface of the die parallel to the sheet material sliding. Most of galling is observed in the areas where lubricant can be forced out of the contact zone, such as edges of the strip, die entry radii or female bead radius.
During the vehicle lifecycle, customers are able to directly perceive the outer panel stiffness of vehicles in various environmental conditions. The outer panel stiffness is an important factor for customers to perceive the robustness of the vehicle. In the real test of outer panel stiffness after prototype production, evaluators manually press the outer panel in advance to identify vulnerable areas to be tested and evaluate the performance only in those area. However, when developing the outer panel stiffness performance using FEA (Finite Element Analysis) before releasing the drawing, it is not possible to filter out these areas, so the entire outer panel must be evaluated. This requires a significant amount of computing resources and manpower. In this study, an approach utilizing artificial intelligence was proposed to streamline the outer panel stiffness analysis and improve development reliability. A deep learning-based prediction technology was developed to predict force-displacement curves of target evaluation points from structural images extracted from the finite element model. Convolutional neural network-based prediction models for the entire outer panel systems were constructed, and the key factors influencing outer panel stiffness were identified and analyzed using the Grad-CAM technique. Additionally, an innovative virtual process was proposed, which uses AI to predict vulnerable areas in advance and perform confirmation analysis solely on those areas. The effectiveness and innovativeness of this process were verified through pilot application in the regular development stage. This process promises a 90% reduction in analysis workload for outer panel stiffness evaluation, significantly boosting vehicle development efficiency. Furthermore, it is expected to significantly improve the drawing completeness.
Soft magnetic cores of electric motors and generators are normally manufactured by stamping individual circular laminates from non-oriented electrical steel (NOES) sheets and stacking them layer by layer to reach the required height. The traditional lamination method can only achieve the average performance of the NOES since the magnetization is in all the directions of the sheet plane. Although NOES is ideal to have isotropic magnetic properties in all the directions of the sheet plane, commercially available electrical steel sheets always show apparent anisotropy in the rotating magnetization directions lying in the sheet plane. The anisotropy in magnetic properties not only causes fluctuations in the rotating magnetic field, but also leads to oscillations in electromagnetic torque, and thus needs to be minimized. In this paper, a novel electrical steel lamination technique is developed, which takes the advantage of the inherent magnetic anisotropy of electrical steel sheets to improve the motor performance by aligning the teeth of the laminates to the electrical steel sheet’s easy magnetization direction while significantly reducing the material waste during the lamination process. This technique differs from the slinky or spiral lamination technology in that individual laminates (instead of a continuous, spiral lamination) are stacked which can significantly reduce the eddy current loss by isolating the individual laminates as in the conventional method. The process to manufacture prototype lamination cores from commercial NOES sheets using this new method is demonstrated in this paper. The potential impact of this manufacturing technology on the motor industry is discussed.
The application of local advanced steels has challenges to overcome such as stampability requirements to meet manufacturing processes. Several technological alternatives have been studied to improve sheet steel formability and this work focuses on material selection. Dual Phase 800 steel has an important performance for structural parts involved in body-in-white (BIW) to reach durability and material impact resistance. On those alternatives references the coating application to reduce the friction coefficient and makes the formability process easier to mitigate drawing stamping issues. The study deals with DP800 formability analysis applied in automotive seats, mainly on anchorage components, searching for alternatives to a better material stampability and local availability with a lower cost. These tests approached formability simulations and FLD (Forming Limit Diagrams) to compare the imported DP800-Uncoated and the local DP800EG + Phosphate steels. Additional tests were made for mechanical and metallurgical properties classification for a complete understanding of themselves. The results indicate a satisfactory formability for coated steels, highlighting the relevance of this concept to contribute to the competitiveness of this technology to achieve a better stamping performance and cost avoidance for automotive industry.
In the 1st generation Toyota "MIRAI" fuel cell stack, carbon protective surface coating is deposited after individual Ti bipolar plate being press-formed into the desired shape. Such a process has relatively low production speed, not ideal for large scale manufacturing. A new coating concept, consisting of a nanostructured composite layer of titanium oxide and carbon particles, was devised to enable the incorporation of both the surface treatment and the press processes into the roll-to-roll production line. The initial coating showed higher than expected contact resistance, of which the root cause was identified as nitrogen contamination during the annealing step that inhibited the formation of the composite film structure. Upon the implementation of a vacuum furnace chamber as the countermeasure, the issue was resolved, and the improved coating could meet all the requirements of productivity, conductivity, and durability for use in the newer generation of fuel cell stacks.
Vacuum suction cups are used as transforming handles in stamping lines, which are essential in developing automation and mechanization. However, the vacuum suction cup will crack due to fatigue or long-term operation or installation angle, which directly affects production productivity and safety. The better design will help increase the cups' service life. If the location of stress concentration can be predicted, this can prevent the occurrence of cracks in advance and effectively increase the service life. However, the traditional strain measurement technology cannot meet the requirements of tracking large-field stains and precise point tracking simultaneously in the same area, especially for stacking or narrow parts of the suction cups. The application must allow multiple measurements of hidden component strain information in different fields of view, which would add cost. In this study, a unique multi-camera three-dimensional digital image correlation (3D-DIC) system was designed and applied to measure the strain concentration of the suction cups while the cups were running the pulling progress. In this technique, a multiplexed quad-cameras DIC system which contains two sets of 3D-DIC system (4 cameras) with different field of view or different measurement directions enables simultaneous measurement of full-filed and hidden parts under the same calibration progress. The first two cameras built a sub-group of the 3D-DIC system, which was used to measure the local strain of the narrow or stacked prats. The other system was used to acquire the strain fields of the entire suction cup. In addition to the experimental test, the fatigue test to see the cracks appeared location. The results of DIC were compared to the fatigue data, and the DIC experimental data validated the crack location. This project aims to help designers and operators thoroughly understand the performance of vacuum cups by investigating the strain concentration and crack location.
EV battery enclosures are a hotbed of subsystem design, materials innovation and vehicle integration. Whether you call them packs, boxes or trays, the structures that envelop and protect EV battery cells and their supporting electrical and thermal-management hardware are among the industry's top subsystem priorities. Optimizing the battery pack involves a host of manufacturing and material choices, mass and package tradeoffs, safety provisions and structural design/engineering challenges, OEM and supplier experts told SAE Media. “Do you want the battery pack bolted into the vehicle or integrated into the body structure?” asked Darren Womack, senior department manager, body and structures, at Magna's global R&D group. Hot stamping, cold stamping, roll-forming, hydroforming, casting and steel, aluminum, composites and thermoplastics - are all raising “lively discussions” in pack development, he noted at a recent meeting of analysts.
An emerging challenge for the extrusion press industry is older hydraulics technology. Many presses continue using inefficient and unreliable hydraulic pumps.
This specification covers a standard chloroprene (CR) rubber stock in the form of molded test slabs.
In this paper, for the front wall of a certain automobile, the defects of drawing splits, excessive thinning and excessive springback in the sheet metal forming process are analyzed and predicted. The stamping process has been simulated. The influence of different technical parameters (blank holder force, stamping speed, die gap and friction coefficient) on the forming results was further investigated using the center composite experiment. Through preliminary finite element simulation, the main drawing defects and trimming springback were analyzed. The second-order response surface model was established to perform the multi-objective optimization design of the stamping process with a NGSA-II genetic algorithm. Based on the relevant simulation data, multiple springback compensations are performed on the die surface to reduce the final springback of the part to meet the requirements. Results have shown that through multi-objective optimization, the stamping dies development cycle is effectively shortened, and the design cost can be reduced. The use of simulation software can improve the reliability of the planning process and the design level of the die, and greatly reduce the machine downtime during production.
The development of new components that have a structural commitment and still achieve mass reduction is becoming increasingly complex and sophisticated materials for production for the automotive market for commercial and passenger vehicles. To achieve this level of demand the use of composite materials such as carbon fiber, glass fiber or a compound of the two has become a reality, however the production rate was still considered a problem for medium volume parts (up to one hundred thousand parts per year). The work demonstrates the construction and simulation of a PoC (proof of concept) using these composites in a warm stamp process where the material a thermoset composite plate is preheated to the working temperature, then it is inserted in a tool preheated stamping, remaining closed for a few minutes where the material is consolidated and then the part is extracted already cured without the need for cooling, thus ensuring the projected production tackt compared to the autoclave curing process that can take hours. The PoC was designed with the aim of evaluating stamping conditions such as: spherical conformation, constant cross section and depth reduction, characteristics that are considered classic problems of the stamping process. Therefore, the work presents a viable proposal to produce items for the automotive market for commercial and passenger vehicles.
Strain-rate sensitivity has been neglected in the simulation of the traditional stamping process because the strain rate typically does not significantly impact the forming behavior of sheet metals in such a quasi-static process, and traditional crank or link mechanical presses lack the flexibility of slide motion. However, the recent application of servo drive presses in stamping manifests improvement in formability and reduction of springback, besides increased productivity and energy savings. An accurate simulation of servo stamping entails constitutive models with strain-rate sensitivity. This study evaluated a few strain rate-sensitive models including the power-law model, the linear power-law model, the Johnson-Cook model, and the Cowper-Symonds model through the exercise of fitting these models to the experimental data of a deep draw quality (DDQ) steel. Curve fitting over segmented strain ranges and grouped strain rates were conducted so that the uniqueness of the identified parameters of each model could be analyzed. The findings of each model’s suitability to be used in finite element software herein can help users select the appropriate constitutive models for simulation of servo stamping.
Rosin is a naturally available organic material obtained especially from pine trees. It finds many usages and applications in areas like soldering, pharmaceuticals, building work, engineering field etc. In this work, an attempt has been made to study experimentally the improvement in strength of rosin at normal stove top temperature by means of combining rosin in various ratios with some important organic hardeners and chemicals of literature importance. A table top book press was fabricated for the purpose of rosin pressing using simple tools like teak wood, bolt and nuts. Experiments were conducted using commonly used kitchen gas stove, fabricated book press, rosin raw material, aluminium sulfate powder, maleic anhydride chemical, acetone, ethanol and saw dust particles for making different combination materials using rosin as the main element. Results showed that, rosin on its own without additives showed higher viscosity and brittleness. When combined with organic hardener aluminium sulfate, rosin produced an improved material with reduced brittleness, good hardness and good energy absorption. And by combining with maleic anhydride chemical, rosin produced a hard monomer with an improvement in energy absorption with better future scopes. Comparatively better material was obtained using saw dust particle reinforced rosin and chemical hardener combination. Improvement in characteristics like viscosity and energy absorbed were observed using experiments at three different temperatures. With this improvements, rosin promises to be a possible future material or material additive like filler in composites with regard to anti-plastic materials or plastic alternatives.
Belt-driven starter generator claw pole electric motors are used in hybrid automobiles to start the engine, charge the battery and to power the electrical system when its engine is running. Shaft and claw pole are important components in the claw pole electric motor. The claw pole is fitted onto the shaft through press-fit force. Press-fit is a widely used fastening process to join two different components by pushing a component inside or over another component with high press force which will create a strong bond between the components. Determining press-fit force required to assemble parts is very complex since it depends on a lot of factors such as mechanical material properties of components, interference fit condition whether it is in Min, mean and max condition, amount of contact pressure induced by contact surface, co-efficient of friction created in between components. The press-fit will help to prevent loosening components from its bond at high torque and speed. More over prediction of press-fit force is required to select pneumatic/hydraulic press machine capacity and to freeze the standard operating procedure in the assembly line. In this journal, the required shaft and claw poles press-fit force predicted to assemble for Min, mean and max fit condition by adopting contact non-linearity and material non-linearity technique in Finite element analysis (FEA) using Ansys Workbench and compared the FEA calculated results with theoretical calculation, physical measurements.
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