Papers by Keyword: Metal Fiber

Abstract: The non-conventional cutting of electrically conductive materials using WEDM and WECM and their hybrid processes is already standard in manufacturing technology. This is essentially based on homogeneous or layered materials. In the future, cellular, wool-like, or similarly structured materials will play a greater role and will be more important; especially the cutting in conjunction with homogeneous materials. In the study, experiments were carried out with a standard WEDM system and a WECM test system. In preliminary tests, various EC machine structures with different flushing and cutting directions have been tested, and because of the static wire arrangement, adjustments to a maximum working current have been tried out. Various feed speeds have been implemented for the test series and the influence of the wool structure on the regulation of the short circuits in the working gap has been analyzed. A modified equivalent circuit diagram has been created from the special features of the processing. The process regulation must be adapted to the special conditions of the spontaneous working gap reduction and thus the higher number of soft short circuits. The study should primarily show where the deviations of the WEDM and WECM from wool structures are; which changes have to be made, especially for process regulation. Secondarily, it was determined which cutting structures arise and whether the partial discharges have a marginal effect on the cutting result in both processes.

Abstract: The expansion of the electronic industry and the extensive use of electronic equipment in communications, computations, automations, biomedicine, space, and other purposes have led to problems such as electromagnetic interference of electronic devices and health issues. For reasons given above, a demand for protection of human being, sensitive electronic and electrotechnic appliances against undesirable influence electromagnetic signals and troublesome charges raised. This paper presents the present state of a fabrication and characterization of multifunctional metal hybrid fabrics with increased resistivity to electromagnetic smog at conserving basic properties of textile structures designated for clothing purposes. The parameters influencing electromagnetic (EM) shielding properties of the hybrid fabrics were investigated. It was shown that the EM shielding effectiveness of the fabrics could be tailored by modifying the metal content, metal grid size and geometry. Furthermore, correlation between electrical properties and EM shielding effectiveness and comfort properties was studied.

Abstract: This study provides a series of investigation on the morphological characteristics and related mechanisms of a porous metal-fiber sintered felt (PMFSF). Multi-tooth cutting and high-temperature solid-phase sintering are used to create the PMFSF. Based on both modeling and experimental methods, the results suggest that the produced fiber has rough surface and curled shape due to cutting deformation. The processing parameters and material mechanical property both have significant effects on formation of fiber morphology. Results also reveal that the fibers in a PMFSF is randomly distributed and connected with each other by forming sintering necks. Besides, the influences of sintering parameters are also analyzed in this work.

Abstract: Along with the wide applications of metal fibers in many fields, more and more attentions were paid on the preparation of metal fibers. Bifurcating chip cutting (BCC) is an effective method of manufacturing slim long metal fibers with high efficiency. In this paper, the chip-bifurcating states were studied in the process of BCC. The states can be classified into four kinds of circumstances according to the experimental results: thorough chip-bifurcating, incomplete chip-bifurcating, part chip-bifurcating and chip-bifurcating entirely but sticking together. Moreover, three chip-bifurcating criteria were proposed to keep the thorough chip-bifurcating state stable. The three chip-bifurcating criteria are found in good agreement with experimental results and can be used as a practical guide for producing slim long metal fibers by BCC.

Abstract: Just like other paper/plastic/aluminum (PPA) composites, Tetra Pak-package-material (Tetra Paks) has excellent water and vapor barrier abilities, and is widely used in food and beverage packaging industry. However, serious environmental problem follows due to its long service life. In this paper, a novel electromagnetic shielding composite board was developed with recycled Tetra Paks and copper-iron mixed fibers. The influence of Cu/Fe ratio and mat configuration on board shielding effectiveness (SE), volume resistivity (VR) and mechanical properties were investigated. The results showed that the boards with copper-iron mixed fiber layers showed better electromagnetic shielding performance than those with only iron or copper fiber layer. The SE of the boards was improved with higher copper fiber content. The location of the metal fiber layers in the mat had a significant influence on board electromagnetic shielding performance. A symmetrical sandwich structure was found beneficial to better shielding performance, and in the same condition of wave frequency and shielding material thickness, the shielding system with a Fe core exhibited better shielding performance than that with a Cu core. The ratio of Cu/Fe and the configuration of mat both had significant influences on mechanical properties of the boards. It can be concluded that qualified electromagnetic shielding composite board could be produced with Tetra Paks wastes and copper-iron mixed fibers. Showing both environmental and economic values, this type of board could be considered as an alternative material used in packaging, interior finish, furniture, and other applications.

Abstract: In order to manufacture slim long metal fibers efficiently, a new type multi-tooth tool is developed. multi-tooth tool has chip-splitting action, namely the whole cutting layer will be split into pieces of metal fibers as all tiny teeth contacting the workpiece are involved in cutting. The oblique cutting model of multi-tooth tool and that of a tooth in the tool are built. The formation mechanism of metal fiber cross section is presented according to different feedrate.

Abstract: Sintered metal fiber structures show a favourable ratio between pressure drop and inner surface area. Their exclusively open-cell morphology makes them well suited for heat transfer or temporary heat storage applications. Recently, highly conductive sintered metal fiber structures were successfully prepared from melt extracted aluminum alloy fibers. The heat conduction and fluid flow properties of metallic sintered short fiber structures were determined experimentally and compared with simple analytical models. It was found that equations taken from the available literature yield good approximations to the experimental results.

Abstract: inno.zellmet is a large funded project which aims at the commercialisation of new, non-foam types of cellular metals. The project focuses on porous structures made from metallic short fibers and structures made from metallic hollow spheres, which are both chararacterised by multifunctionality and low specific weight. Six research institutes and 17 partners from industry constitute a local network that jointly develops solutions based on these "constructed materials". Target applications are situated in industrial sectors such as light-weight construction, decentralised energy generation, medical and biotechnology, as well as sound absorption and explosion protection for stationary machinery. inno.zellmet has started in March 2005 and will run for 3 years. During this time, it receives 3.9 Mio. EUR in funding from the German Federal Ministry of Education and Research under the "Unternehmen Region" initiative. This paper highlights some of the results obtained so far.

Abstract: Stainless steel and Ti metal fibers having a diameter of 3 µm were produced from wires by multiple extrusions. The suitable sheath coating for stainless steel to extrude the core wires to fibers was the Cu coating having ~30 µm thickness. Zinc was not a suitable sheath coating, because Zn of the low melting point had diffused into the stainless steel wires during extrusion. The oxidation of stainless steel fibers produced using the Cu sheath coating oxidized rapidly above 750°C due to the high surface area of fibers. The utilization of the Cu coating as a sheath material to extrude the core Ti wires to fibers was not possible, because the highly reactive Ti wires resisted deforming to fibers.