• JLA Vol:4 Iss:1 (Combustion‐Assisted Laser Cutting of a Difficult‐to‐Machine Superalloy)


    Authors:
    P. A. Molian
    M. Baldwin



    In laser cutting, the largest single application of lasers in manufacturing, the assist gas plays an important role in affecting the cutting performance. The assist gas is usually oxygen or an inert gas. In this work a mixture of acetylene and oxygen was employed to create combustion reactions during CO2 laser cutting that enabled an improvement in the cutting speed, and cut quality of a difficult‐to‐machine superalloy. A comparison with laser cutting of a plain carbon steel under identical conditions was also made to determine the usefulness of combustion energy. Results indicate that both cutting speed and qual...

    $25.00

  • JLA Vol:1 Iss:3 (CO<sub>2</sub> Laser Engraving System for Relief Plate to Print Corrugated Cardboard)


    Authors:
    K. Wakabayashi
    N. Sugishima
    NEC Corporation, Laser Equipment Div., 1120, Shimokuzawa, Sagamihara, JAPAN


    A very compact and economical CO2 laser engraving system to make relief plates for the purpose of printing corrugated cardboard has been developed. This system consists of a highly stable 500W CO2 laser and a high speed, easy handling image processing sub&hyphen;system. In this paper several new developments are described. This image processing technique for CO2 laser raster scanning and engraving has been newly developed. Every binary image is converted to the relief plate more easier than other reported engraving systems.

    $25.00

  • JLA Vol:14 Iss:1 (Physical&ndash;computational model to describe the interaction between a laser beam and a powder jet in laser surface processing)


    Authors:
    O. O. Diniz Neto
    Array

    R. Vilar
    Departamento de Engenharia de Materiais, Instituto Superior Te´cnico, 1049-001 Lisboa, Portugal


    Frequently laser surface treatments use a powder jet in conjunction with the laser beam. In this study we present a physical–computational model to describe the interaction between a laser beam and a powder jet. The model can be used to calculate the spatial distribution of particle temperature and laser beam attenuation at any moment and all over the region where the laser and particle beams interact. In calculating particle temperature, the attenuation of the laser beam by the particles themselves is taken into acc...

    $25.00

  • JLA Vol:18 Iss:2 (Fabrication of titanium microchannels using laser-assisted thermochemical wet etching)


    Authors:
    S. W. Son
    M. K. Lee
    K. H. Oh
    S. H. Jeong
    Department of Mechatronics, Gwangju Institute of Science and Technology, 1 Oryongdong Bukgu, Gwangju, 500-712 Republic of Korea


    A fabrication method of titanium microchannels of an aspect ratio up to 16 and channel width of 10–30 μm is developed using laser-assisted thermochemical wet etching. For the fabrication of deep channel, the workpiece was repeatedly etched over the same path with the control of process parameters. The cross-sectional profile of the microchannel varied between a V shape and a U shape, depending largely upon the laser beam power and etchant concentration. Bubb...

    $25.00

  • JLA Vol:23 Iss:4 (Evaluation of the bone repair in defects grafted with hydroxyapatite and collagen membrane combined with laser therapy in rats)


    Authors:
    Marcelo Rodrigues da Cunha
    Luanda de Abreu Figueira
    Joa˜o Paulo Mardegan Issa
    Ricardo Alexandre Junqueira Calzzani
    Daniele Cristina do Prado Ribeiro
    Amilton Iatecola
    Mariane Silva Pettian
    Array


    Bone regeneration is the result of cellular events such as osteogenesis and neovascularization. However, implantation of autogenous grafts may be necessary in cases of bone mass loss due to high impact trauma. The disadvantages of the latter approach include morbidity of the donor area. Biomaterials represent an alternative for bone restoration. The most widely used compounds are collagen or hydroxyapat...

    $25.00

  • JLA Vol:6 Iss:2 (CO<sub>2</sub> shielding gas effects in laser welding mild steel)


    Authors:
    D. H. Abbott
    C. E. Albright



    The most widely used shielding gases for laser welding of steels are helium and argon. Helium produces significantly more penetration than argon in penetration&hyphen;mode laser beam welding. Another gas that has been proposed as an alternative to these inert gases is carbon dioxide. The benefits of using carbon dioxide as a shielding gas for laser welding are that it costs less than helium and argon and that it provides nearly the same penetration as helium. The major drawback to its use as a shielding gas for mild steel is that it can cause porosity and other weld discontinuities. In this investigation helium and carbon dioxide were...

    $25.00

  • JLA Vol:8 Iss:2 (Recent progress in laser surface treatment: <emph type="4">II</emph>. Adopted processing for high efficiency and quality)


    Authors:
    W. Bloehs
    B. Gru¨nenwald
    F. Dausinger
    H. Hu¨gel
    Institut fu¨r Strahlwerkzeuge, Universita¨t Stuttgart, Pfaffenwaldring 43, 70569 Stuttgart, Germany


    In Part I of this contribution, energy coupling and transport mechanisms were considered in detail. The second part concentrates on the effect of the spatial distribution of the energy in the laser beam, which will be discussed in connection with applications of laser surface technologies. Along these lines, a variety of beam shaping facilities is presented for laser hardening and cladding. Their purpose is to adapt the irradiated area to the workpiece ge...

    $25.00

  • JLA Vol:2 Iss:3 (Energy Coupling in Surface Treatment Processes)


    Authors:
    Friedrich Dausinger
    Markus Beck
    Jae H. Lee
    Eckhard Meiners
    Thomas Rudlaff
    Jialin Shen
    Institut fu¨r Strahlwerkzeuge, University of Stuttgart, Federal Republic of Germany


    In cutting or welding processes with lasers, deep penetration mechanisms allow high energy coupling rates. In surface treatment processes such as martensitic hardening, cladding and alloying, deep penetration of the laser beam is mostly not applicable. This generally leads to insufficient coupling rates. In this contribution several ways of enhancing the coupling rate are summarized. Following some theoretical considerations, results of exp...

    $25.00

  • JLA Vol:24 Iss:5 (Development of new processes for welding of thermal Al&ndash;Cu solar absorbers using diode lasers)


    Authors:
    Andre Springer
    Peter Kallage
    Michael Hustedt
    Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany

    Stephan Barcikowski
    University of Duisburg-Essen, Technical Chemistry I, Universitaetsstr. 5–7, 45141 Essen, Germany

    Volker Wesling
    Heinz Haferkamp
    Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany


    Flat-plate solar collectors are favorable devices to generate heat from the energy of the Sun. The central part of a collector, the solar absorber, is a front-coated aluminum sheet with a copper tube fixed on the back side in order to transport heated liquid. ...

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  • JLA Vol:14 Iss:3 (Assessment of laser Doppler perfusion imager&rsquo;s <em>in vivo</em> reliability: Can it be used for a prospective analysis?)


    Authors:
    Antonella Caselli
    Array

    Damanpreet Singh Bedi
    Colleen O’Connor
    Chirag Shah
    Aristidis Veves
    Joslin–Beth Israel Deaconess Foot Center, Department of Surgery, and Microcirculation Laboratory, Beth Israel–Deaconess Medical Center, Harvard Medical School, Boston, Massachusetts


    The aim of this study was to assess the reliability of the laser Doppler perfusion imager (Lisca PIM 1.0; Lisca development, Linkoping, Sweden) for longitudinal analysis. We measured the skin blood flow under a biological zero condition at the forearm level in 84 patients enrolled in a 12 week prospective interventional trial. Sin...

    $25.00

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