• JLA Vol:15 Iss:3 (Steady-state laser cutting modeling)

    Ce´dric Mas
    Re´my Fabbro
    CLFA, 16 bis Avenue Prieur de la Côte d’Or, 94114 Arcueil Cedex, France

    Yannick Goue´dard
    OPTIS, ZE la Farlède, BP 275, 83078 Toulon Cedex 9, France

    We present a global self-consistent model of the laser cutting process where we have taken into account the main parameters of the process that are the laser beam intensity distribution, the thermal phenomena controlling the melt parameters, the fluid, both cutting gas and melt hydrodynamics, and the local equilibrium of the geometry of the cutting front. This steady state approach provides us with different fluid velocities, surface ...


  • JLA Vol:15 Iss:3 (Three-dimensional finite element modeling of laser cladding by powder injection: Effects of powder feedrate and travel speed on the process)

    Ehsan Toyserkani
    Amir Khajepour
    Steve Corbin
    University of Waterloo, Department of Mechanical Engineering, Waterloo, Ontario N2L 3G1, Canada

    This article addresses a novel three-dimensional transient finite element model of the laser cladding by powder injection process. The proposed model can predict clad geometry as a function of time and process parameters including beam velocity, laser power, powder jet geometry, laser pulse shaping, and material properties. In the proposed method, the interaction between powder and melt pool are assumed to be decoupled and as a result, the melt pool boundary is first obtained in the absence of powder spray....


  • JLA Vol:15 Iss:4 (Condition monitoring and lifetime estimation of a CO<sub>2</sub> laser)

    P. Koomsap
    V. V. Prabhu
    N. I. Shaikh
    J. T. Schriempf
    J. H. McDermott
    The Pennsylvania State University, University Park, Pennsylvania 16802

    Lasers are being successfully applied to a variety of manufacturing processes, including cutting, welding, cladding, and free forming. Part of their success is due to the high quality beam that is directly related to the condition of components involved in the lasing process. However, maintaining the requisite beam quality requires frequent and time-consuming intervention by maintenance operators, specifically, for dismounting, inspection, servicing, and reassembly. Preventive maintenanc...


  • JLA Vol:15 Iss:4 (Design and performance of multilevel phase fan-out diffractive optical elements for laser materials processing)

    Keiji Fuse
    Takayuki Hirai
    Toshihiko Ushiro
    Takeshi Okada
    Kenichi Kurisu
    Keiji Ebata
    Itami R&D Laboratories, Sumitomo Electric Industries, Ltd., 1-1-3 Shimaya, Konohana-ku, Osaka 554-0024, Japan

    A multilevel phase fan-out diffractive optical element (DOE) has been developed and introduced into various kinds of laser materials processing such as drilling, cutting, welding, and soldering. The larger the number of arrayed spots the DOE generates on the surface of the workpiece, the more sensitive the intensity uniformity of the spots becomes to fabrication errors, which are deviations between designed and fabric...


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

    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 ...


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

    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...


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

    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...


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

    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 ...


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

    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...


  • 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)

    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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