Modelling of aluminium sheet forming at elevated temperatures

The formability of Al–Mg sheet can be improved considerably, by increasing the temperature. By heating the\ud sheet in areas with large shear strains, but cooling it on places where the risk of necking is high, the limiting drawing ratio\ud can be increased to values above 2.5. At elevated temperatures, the mechanical response of the material becomes strain rate\ud dependent. To accurately simulate warm forming of aluminium sheet, a material model is required that incorporates the\ud temperature and strain-rate dependency. In this paper simulations are presented of the deep drawing of a cylindrical cup,\ud using shell elements. It is demonstrated that the familiar quadratic Hill yield function is not capable of describing the plastic\ud deformation of aluminium. Hardening can be described successfully with a physically based material model for temperatures\ud up to 200 �C. At higher temperatures and very low strain rates, the flow curve deviates significantly from the mode

Micro Deep Drawing of C1100 Conical-cylindrical Cups

AbstractMicro deep drawing was prompted by the rapid development of micro electro mechanical systems, electron industries, new energy, and biomedical in recent years because of its mass production, high efficiency, high precision, low cost and no pollution. However, most researches concentrated on micro cylindrical cups, few studies were reported on other shaped parts. Micro deep drawing of micro conical-cylindrical cups was investigated in this study by using a micro blanking-deep drawing multiple operation mould. The specimen material was pure copper C1100 with a thickness of 50μm which was thermally treated in vacuum condition at 723K for 1h. Micro deep drawing experiments were carried out at room temperature on a universal testing machine at a drawing velocity of 0.05mm/s with the lubrication of polyethylene (PE) film. The results showed that micro conical-cylindrical cups with internal conical bottom diameter of only 0.4mm were well formed. The drawing force and limiting drawing ratio (LDR) micro conical-cylindrical cups were also discussed at the end of this paper

A novel approach towards a lubricant-free deep drawing process via macro-structured tools

In today’s industry, the sustainable use of raw materials and the development of new green technology in mass production, with the aim of saving resources, energy and production costs, is a significant challenge. Deep drawing as a widely used industrial sheet metal forming process for the production of automotive parts belongs to one of the most energy-efficient production techniques. However, one disadvantage of deep drawing regarding the realisation of green technology is the use of lubricants in this process. Therefore, a novel approach for modifying the conventional deep drawing process to achieve a lubricant-free deep drawing process is introduced within this thesis. In order to decrease the amount of frictional force for a given friction coefficient, the integral of the contact pressure over the contact area has to be reduced. To achieve that, the flange area of the tool is macro-structured, which has only line contacts. To avoid the wrinkling, the geometrical moment of inertia of the sheet should be increased by the alternating bending mechanism of the material in the flange area through immersing the blankholder slightly into the drawing die

Aluminum Alloys Behavior during Forming

Industrial revolution toward weight reduction and fuel efficiency of the automotive and aerospace vehicles is the major concern to replace heavy metals with light weight metals without affecting much strength. For this, aluminum alloys are the major contributors to those industries. Moreover, aluminum alloys are majorly categorized as 1xxx, 2xxx, 3xxx, 4xxx, 5xxx, 6xxx, 7xxx, and 8xxx based on major alloying elements. Among all, 2xxx, 5xxx, 6xxx, and 7xxx are having majority of applications in the abovementioned industries. For manufacturing any engineering deformable components, forming characteristics are must. Forming behavior of aluminum alloys has been evaluated through different processes including deep drawing, stretching, incremental forming, bending, hydro forming etc., under different process conditions (cold, warm, and hot conditions) and process parameters. Each process has its own process feasibility to evaluate the formability without any forming defects in products. The present chapter discusses a few important processes and their parameter effect on the aluminum alloys through the experimentations and simulation works

Al-Cu Composite’s Springback in Micro Deep Drawing

With the recent technological trend of miniaturization in manufacturing industries, the rise of micro forming operations such as micro deep drawing (MDD) is inevitable. On the other hand, the need of more advanced materials is essential to accommodate various applications. However, a major problem are size effects that make micro scale operations challenging. One of the most important behaviors affected by size effects is the springback phenomenon, which is the tendency of a deformed material to go back to its original shape. Springback can affect dimensional accuracy, which is very important in micro products. Thus, this paper investigated the springback behavior of Al-Cu composite in MDD operations. Micro cups were fabricated from blank sheet specimens using an MDD apparatus with variation of annealing holding time. The springback values were measured and compared to each other. The results showed that different grain sizes lead to variation in the amount of springback. However, unlike in single-element materials, the amount of springback in Al-Cu composite is not only related to the thickness to grain size (t/d) ratio. Another factor, i.e., the existence of an interfacial region between layers, alters the mechanical behavior of the composite

Cold Micro Metal Forming

This open access book contains the research report of the Collaborative Research Center “Micro Cold Forming” (SFB 747) of the University of Bremen, Germany. The topical research focus lies on new methods and processes for a mastered mass production of micro parts which are smaller than 1mm (by forming in batch size higher than one million). The target audience primarily comprises research experts and practitioners in production engineering, but the book may also be of interest to graduate students alike

Metal Micro-forming

The miniaturization of industrial products is a global trend. Metal forming technology is not only suitable for mass production and excellent in productivity and cost reduction, but it is also a key processing method that is essential for products that utilize advantage of the mechanical and functional properties of metals. However, it is not easy to realize the processing even if the conventional metal forming technology is directly scaled down. This is because the characteristics of materials, processing methods, die and tools, etc., vary greatly with miniaturization. In metal micro forming technology, the size effect of major issues for micro forming have also been clarified academically. New processing methods for metal micro forming have also been developed by introducing new special processing techniques, and it is a new wave of innovation toward high precision, high degree of processing, and high flexibility. To date, several special issues and books have been published on micro-forming technology. This book contains 11 of the latest research results on metal micro forming technology. The editor believes that it will be very useful for understanding the state-of-the-art of metal micro forming technology and for understanding future trends

Deformation Mechanics and Microstructure Evolution During Microforming of Metals

Deformation mechanics including dynamic strain, strain-rate and rotation of material elements and its spatio-temporal scaling behavior was studied using in situ characterization of prototypical microforming operations- Equal Channel Angular Pressing (ECAP), Indirect Extrusion (IE) and Deep Drawing (DD) across length scales (sub-millimeter and micron). Microforming devices including ECAP, IE and DD dies in plane strain condition were designed and fabricated to manifest process outcomes/anomalies in small length-scale deformations for a range of imposed strains: severe (ECAP), moderate (IE) and low (DD). This was captured by conducting in situ experiments on commercially pure metals: Ni 200, Oxygen Free High Conductivity (OFHC) Cu, Al 1100 and Pb. Set up microforming stages capable of in-situ observation in various length scales were implemented to employ Digital Image Correlation (DIC) technique in order to quantify the mechanics of deformation particularly in deformation zone where the temperature filed captured by in situ Infra-Red (IR) thermography completed the detailed understanding of thermomechanical phenomena prevail in microforming operations. To do this, ECAP and IE devices were designed with a transparent viewing window made of Sapphire block enables the imaging of the material flow during deformation using high-speed (CCD) and IR cameras. While DD of metallic sheets was performed in a microforming setup that sits inside the chamber of Scanning Electron Microscope (SEM) enables in situ characterization of material flow behavior using SEM based DIC. Pre and post–Mortem Microstructure analysis was carried out by performing Orientation Imaging Microscopy (OIM) across the microformed machine elements aiming to correlate spatially evolved microstructures/textures across the deformation zone with the mechanics of deformation obtained by in situ observations for the given materials system. In microforming, variables such as initial microstructure, process configuration and tooling design along with the deformation process parameters are known as crucial factors that determine the deformation behavior of material and therefore the process consequences including failure characteristics and quality of microparts surface finish. In the present dissertation, the effect of process parameters and scaling was studied and the role of characteristics of prior microstructures such as grain size and its distribution, grain morphology, twin size and density, pre-existing textures, etc. and their contribution in improving or disproving the formability was delineated for different deformation geometries and material systems. These studies revealed the strong dependence of the morphology and characteristics of plastic deformation zone (PDZ) to the process outcomes e.g. microstructure evolution, surface roughening, sudden failure, etc. which are the results of the mechanical/microscopical responses of material to the geometric confinements and strain gradients. The systematic studies of the effect of microscopic/macroscopic boundary conditions allows to determine the presence of any spatial confinement switchover in the mechanism of microscopic material response that will be eventually appeared in the quality of micro-machined components