• JLA Vol:15 Iss:4 (Excimer laser fabrication of polymer microfluidic devices)


    Authors:
    Joohan Kim
    Xianfan Xu
    School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907


    Silicon has been a primary material for fabrication of microelectromechanical systems (microfluidic devices in MEMS) for several decades. This is due to the fact that the MEMS techniques were derived from those used for microfabrication in the semiconductor industry. These techniques are well developed, and can be readily applied for silicon based MEMS fabrication. Nowadays, alternative manufacturing materials and techniques are needed for reducing costs and meeting new requirements. Polymers have many advantages because of their low costs and applications in ...

    $25.00

  • JLA Vol:15 Iss:4 (Induction heat treatment of laser welds)


    Authors:
    Claus Bagger
    Joakim Ilsing Sørensen
    Flemming O. Olsen
    Manufacturing Engineering and Management, Materials and Process Technology, Technical University of Denmark, Building 425, DK-2800 Lyngby, Denmark


    In this article, a new approach based on induction heat treatment of flat laser welded sheets is presented. With this new concept, the ductility of high strength steels GA260 with a thickness of 1.8 mm and CMn with a thickness of 2.13 mm is believed to be improved by prolonging the cooling time from 750 to 450 °C. Initially, a simple analytical model was used to calculate the ideal energy contributions from a CO2 high power laser s...

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  • JLA Vol:15 Iss:4 (Laser rapid-alloy prototyping for the development of wear resistant Fe–Cr–C/NbC composite materials)


    Authors:
    R. Colac¸o
    R. Vilar
    Instituto Superior Te´cnico, Department of Materials Engineering, Avenue Rovisco Pais 1049-001, Lisboa, Portugal


    In this article a novel methodology for the development of hardfacing materials, the so-called laser-assisted rapid-alloy-prototyping technique, based on variable powder feed rate laser cladding, is described. An Fe–Cr–C metallic matrix composite, reinforced with NbC carbide particles, was chosen as a case study for the application of the methodology. First, the criteria for the design of the matrix and type of reinforcement particles are described. Then, the approach used for the optimization of the material...

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  • JLA Vol:15 Iss:4 (Laser–material interaction and process sensing in underwater Nd:yttrium–aluminum–garnet laser welding)


    Authors:
    Xudong Zhang
    Wuzhu Chen
    Department of Mechanical Engineering, Tsinghua University, Beijing 100084, China

    Eiji Ashida
    Fukuhisa Matsuda
    Tarasaki R&D Center, JAPEIC, Hitachinaka, Ibaraki 312-0003, Japan


    Laser–material interaction and process sensing technology for local-dry underwater Nd:yttrium–aluminum–garnet laser beam welding were studied. The optical emissions induced by laser–water interaction were detected with an infrared (IR) optical sensor and observed with a charge coupled device camera. It was found that under laser irradiation, a kind of water–vapor plasma formed immediately above the ...

    $25.00

  • JLA Vol:15 Iss:4 (Laser-assisted etching of titanium foil in phosphoric acid for direct fabrication of microstructures)


    Authors:
    Y. S. Shin
    S. H. Jeong
    Department of Mechatronics, Kwangju Institute of Science and Technology, 1 Oryong-dong Puk-gu, Kwangju 500-712, Republic of Korea


    Characteristics of laser-induced thermochemical wet etching of titanium foil in phosphoric acid were investigated to examine the feasibility of this method for direct fabrication of microstructures. Variations of etch width, depth, and profile were examined for different combinations of laser power density, scanning speed of the beam focus, and etchant concentration which are the major process parameters governing temperature distribution on the sample surface and the reaction rate. Etch width increased almost li...

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  • JLA Vol:15 Iss:4 (Selective decolorization of pigments within two and three pigmented inks for colored marking by a <em>Q</em>-switched laser)


    Authors:
    R. Stewart
    L. Li
    Department of Mechanical, Aerospace and Manufacturing Engineering, Laser Processing Research Centre, University of Manchester Institute of Science and Technology (UMIST), P.O. Box 88, Manchester M60 1QD, United Kingdom


    Inks consisting of two and three pigments as well as an infrared absorber were printed onto plain paper and treated using a Q-switched Nd:yttrium–aluminum–garnet laser. It has been shown that the color of these inks can be altered through selective pigment decay: a red, green and blue ink decayed red first, then green, leaving a blue mark or a purple one, selectively. The process is related to the thermal decom...

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  • JLA Vol:15 Iss:4 (Solution of two-temperature thermal diffusion model of laser&ndash;metal interactions)


    Authors:
    S. R. Vatsya
    Kuljit S. Virk
    Integrated Manufacturing Technologies Institute, National Research Council of Canada, 800 Collip Circle, London, Ontario N6G 4X8, Canada


    The two temperature coupled equations, modeling thermal diffusion during laser-induced ablation of metals, are solved under the assumptions that the electron and the lattice heat capacities, and the thermal conductivity remain constant in the process. In view of its practical value, the solution is initially obtained for the energy sources with a Gaussian distribution. The solution is then generalized to include a larger class of source terms for comparison with other results. Present analysis is vali...

    $25.00

  • JLA Vol:15 Iss:4 (Steel microstructures in autogenous laser welds)


    Authors:
    N. A. McPherson
    BAE Systems, Naval Ships, Glasgow, Scotland, United Kingdom

    H. Samson
    BAE Systems, Submarines, Barrow, England, United Kingdom

    T. N. Baker
    N. Suarez-Fernandez
    University of Strathclyde, Glasgow, Scotland, United Kingdom


    Autogenous Nd:YAG laser welding was carried out on austenitic stainless steel (316LN) and duplex stainless steel (2205). The structures were examined using optical and color etching metallography. This showed optically that the austenitic steel solidified as a totally austenitic structure, but the transmission electron microscopy (TEM) work confirmed the presence of ferrite. In the case o...

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  • JLA Vol:15 Iss:4 (Strain gauge analysis of laser forming)


    Authors:
    S. P. Edwardson
    K. G. Watkins
    G. Dearden
    P. French
    Department of Engineering, Laser Group, The University of Liverpool, Liverpool L69 3GH, United Kingdom

    J. Magee
    National Centre for Laser Applications, NUI Galway, Ireland


    Laser forming has become a viable process for the shaping of metallic components, as a means of rapid prototyping and of adjusting and aligning. The laser forming process is of significant value to industries that previously relied on expensive stamping dies and presses for prototype evaluations. This investigation aims to complement the considerable amount of work already completed on two-dimensi...

    $25.00

  • JLA Vol:15 Iss:4 (Surface melting of Al&ndash;Cu&ndash;Mg alloy using a short-pulse, planar waveguide CO<sub>2</sub> laser for corrosion resistance improvement)


    Authors:
    M. G. Tsagkarakis
    F. J. Villarreal
    H. J. Baker
    D. R. Hall
    School of Engineering and Physical Sciences, Heriot-Watt University, Edinburgh EH14 4AS, United Kingdom

    S. W. Williams
    BAE Systems, Advanced Technology Centre, Filton, Bristol BS34 7QW, United Kingdom


    A newly available pulse format for planar waveguide carbon dioxide lasers has been investigated for surface melting treatment of Al-2024 using 35–40 μs duration pulses. A single-pass raster scan produces crack free surfaces, but with considerable surface modulation and stress. A double-pass treatment has been shown to relieve the stress and smooth the s...

    $25.00

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