• JLA Vol:15 Iss:2 (Automatic detection of lack of fusion defects in CO<sub>2</sub> laser gear welding)

    A. Ghasempoor
    Department of Mechanical, Aerospace, and Industrial Engineering, Ryerson University, Toronto, Ontario M5B 2K3, Canada

    P. Wild
    M. Auger
    Department of Mechanical Engineering, Queen’s University, Kingston, Ontario K7K 3N6, Canada

    R. Mueller
    Powerlasers Ltd., Advanced Technologies Centre, Kitchener, Ontario N2G 2Y5, Canada

    Laser welding is becoming increasingly important in the automotive industry and quality of the weld is critical for a successful application. In many cases the increase in welding speed provided by laser welding has resulted in the need for an automated, on-line weld monitoring system....


  • JLA Vol:15 Iss:2 (Characteristics of high-power diode&ndash;laser welds for industrial assembly)

    C. A. Walsh
    H. K. D. H. Bhadeshia
    Department of Materials Science and Metallurgy, University of Cambridge, United Kingdom

    A. Lau
    B. Matthias
    R. Oesterlein
    ABB Corporation Research, Ladenburg, Germany

    J. Drechsel
    Laserinstitut Mittelsachsen e.V., Mittweida, Germany

    Recent progress in available beam power and beam quality has meant that high power diode lasers may soon become prime tools for welding in many assembly applications in industrial production. Their compact size and low weight makes them particularly suitable for use in conjunction with robotic control. The advantages of laser welding ...


  • JLA Vol:15 Iss:2 (Copper vapor laser micromachining of 304 stainless steel)

    M. El-Bandrawy
    K. Nagarathnam
    Mool C. Gupta
    Applied Research Center, College of Engineering and Technology, Old Dominion University, Newport News, Virginia 23606

    C. Hamann
    J. Horsting
    Siemens Automotive, Newport News, Virginia 23606

    A copper vapor laser (CVL) of 511/578 nm wavelength, 25 ns pulse width, and 10 kHz repetition rate combined with a computer controlled galvo head was used for laser micromachining of 304 stainless steel. The objective of this study was to develop the CVL micromachining process and its optimization. We observed a significant improvement in micromachining quality with a spatially filtered ...


  • JLA Vol:15 Iss:2 (Corrosion resistance of laser-fabricated metal&ndash;matrix composite layer on stainless steel 316L)

    K. H. Lo
    Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    C. T. Kwok
    Department of Electromechanical Engineering, Faculty of Science and Technology, University of Macau, Taipei, Macau, China

    F. T. Cheng
    Department of Applied Physics, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    H. C. Man
    Department of Manufacturing Engineering, The Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong, China

    Laser fabrication of ceramic-reinforced metal–matrix composite (MMC) layer on stainless steel 316L was achieved by a two-st...


  • JLA Vol:15 Iss:2 (Critical parameters of light emitting diodes and their implications on the optical radiation safety limits according to IEC 60825-1 +Amendment 2)

    W. Horak
    R. Neuhaus
    Siemens AG, 81730 Munich, Germany

    Radiation power and image size of the source on the viewer's retina (apparent source) determines the hazard for the eye. Following IEC 60825-1, the effective emission limits are dependent on the tabulated accessible emission limits and the assigned measurement conditions—both depending on the source size. In the case of a light emitting diode (LED), this emitting area is not only determined by the chip size but also by the housing—due to built-in lenses, reflectors, and scattering materials. Also the virtual source position will be distorted by the integrated lenses. Since the measurement distance ...


  • JLA Vol:15 Iss:2 (Laser forming of thin foil by a newly developed sample holding method)

    Shunro Yoshioka
    Toshiyuki Miyazaki
    Tadashi Misu
    Ryugo Oba
    Masatoshi Saito
    Chiba Institute of Technology, Tsudanuma, Narashino-shi, Chiba 275-0016, Japan

    A sample holding method is newly developed for laser forming, in which the target material is held between two transparent plates. During laser beam scanning on the target, the target foil is kept flat. After the scanning is finished, the foil is detached from the holder; the foil bends toward the beam scanned surface. Experiments are carried out with a Nd:yttrium–aluminum–garnet laser beam for a spot size of 25μm and for a traverse speed of 10 mm/s. A bending...


  • JLA Vol:15 Iss:2 (Laser surface processing of titanium in air: Influence of scan traces overlapping)

    A. Pe´rez del Pino
    P. Serra
    J. L. Morenza
    Departament de Fı´sica Aplicada i Òptica, Universitat de Barcelona, E-08028 Barcelona, Spain

    Laser surface treatments of titanium in air have been performed through a pulsed Nd:yttrium–aluminum–garnet (λ=1.064 μm) laser. Several samples have been obtained modifying the laser scan velocity and partial overlapping of consecutive traces, in order to study the influence of these parameters on the surface morphology. Scanning electron microscopy and profilometry measurements have revealed different surface morphologies depending on the physical processes involved in th...


  • JLA Vol:15 Iss:2 (Optimization and modeling of laser forming of stainless steel circular sectors)

    G. Casalino
    A. D. Ludovico
    Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, Bari 70126, Italy

    Mold-less forming produces precise metal parts by thermal variation generated used high power beam irradiation. Some technologies like the laser and the plasma arc have proved to fit the requirements of this new forming technique [M. Geiger and F. Vollersten, Ann. CIRP 42, 301–304 (1993); P. J. Li et al., J. Eng. Manuf. Proc. Part B 214, 0954–4054 (2000)], which can be applied both for rapid prototyping and rapid manufacturing. In particular, a complex shape can be generated using curved path for the irradiating strategy o...


  • JLA Vol:15 Iss:2 (Plasma assisted laser surface alloying)

    M. H. McCay
    C. M. Sharp
    J. A. Hopkins
    The Center for Laser Applications, The University of Tennessee Space Institute, Tullahoma, Tennessee 37388

    B. Szapiro
    The Department of Physics, University of the South, Sewanee, Tennessee

    T. D. McCay
    The Center for Laser Applications, The University of Tennessee Space Institute, Tullahoma, Tennessee 37388

    The combination of plasma arc with a Nd:YAG laser during surface alloying produces a synergistic effect which significantly increases the depth of the melt pool beyond that expected by a summation of the individual depths. Incremental increases in laser power produce ...


  • JLA Vol:15 Iss:3 (Continuous wave laser ignition thresholds of coal dust clouds)

    Thomas H. Dubaniewicz
    Kenneth L. Cashdollar
    Gregory M. Green
    National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, P.O. Box 18070, Pittsburgh, Pennsylvania 15236

    Laser-based instruments are used in areas where coal dust ignition presents a safety hazard. The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory (NIOSH, PRL) is conducting a study to help determine when an optical beam may be considered a potential ignition source in underground coal mines or coal storage facilities. Researchers conducted experiments to determine threshold igniting powers for Pittsburgh seam bituminous co...