• JLA Vol:8 Iss:6 (Control and optimization of the laser cladding process using matrix cameras and image processing)

    F. Meriaudeau
    F. Truchetet
    Laboratoire GERE — Universite´ de Bourgogne, 12 rue de la Fonderie, 71200 Le Creusot, France

    The laser cladding process, which consists of adding a melted powder on to a substrate in order to improve or change the behavior of the material against corrosion or fatigue, involves many parameters. In order to produce good tracks some of these parameters need to be controlled during the process. We present a low cost system using two charge coupled device (CCD) matrix cameras. One camera provides surface temperature measurements while the other gives information about the powder distribution or geometric characteristics of the tr...


  • JLA Vol:8 Iss:6 (Laser surface alloying of magnesium base alloys)

    R. Galun
    A. Weisheit
    B. L. Mordike
    Institut fu¨r Werkstoffkunde und Werkstofftechnik, Technische Universita¨t Clausthal, Agricolastraße 6, D‐38678 Clausthal‐Zellerfeld, Germany

    The feasibility of the laser surface alloying of magnesium base alloys with aluminum, copper, nickel and silicon has been shown in this work. By laser alloying with these elements, using a 5 kW CO2‐laser, the hardness of several magnesium base alloys can be increased to values above 250 HV0.1. Melted depths from 700–1200 μm and alloying contents from 15–55 at % were achieved. The wear resistance of ...


  • JLA Vol:8 Iss:6 (Teaching laser principles with nitrogen laser pumped dye lasers)

    David H. Lieberman
    Physics Department, Queensborough Community College, 222‐05 56th Ave., Bayside, NY 11364‐1497, U.S.A.

    Nitrogen laser pumped dye lasers are useful aids to the understanding of the principles of lasers and also as tools for advanced undergraduate physics and chemistry laboratories. We have developed laboratory exercises that allow the students to develop necessary skills and study important principles. The students construct their own narrow linewidth dye lasers in a step‐by‐step process. First amplified spontaneous emission is studied and compared with broadband lasing. A grating is added to provide linewidth narrowing and tunabil...


  • JLA Vol:8 Iss:6 (The Influence of laser cavity gaseous impurities on the performance of an industrial CO<sub>2</sub> laser)

    C. R. Hsu
    C. E. Albright
    A. Khakhalev
    Welding Engineering, The Ohio State University

    Contamination in the cavities of high power industrial CO2 lasers is a cause of laser performance degradation. Such degradation can result in laser downtime and significant loss of productivity. The laser cavity gas supply can contribute to this contamination, but there is confusion about the level of gas impurity concentration which can cause a degradation process. The overall objective of this investigation was to study the effects of cavity gas contaminants on the performance of an industrial fast&hyphen;axial&hyphen;flow CO2 laser. A 3 kW fa...


  • JLA Vol:8 Iss:6 (Understanding high&hyphen;power fiber&hyphen;optic laser beam delivery)

    Boyd V. Hunter
    Keng H. Leong
    Carl B. Miller
    James F. Golden
    Robert D. Glesias
    Patrick J. Laverty

    Fiber&hyphen;optic beam delivery is commonly used in industrial laser systems. This article examines the conditions for the optimal propagation of high power beams through optical fibers. Beam quality effects by step and gradient index fibers of different lengths are considered. The differences between the diverging beam from a fiber and the beam at focus and on the fiber face are illustrated. Estimates are provided of the worst&hyphen;case beam quality to be expected from fibers. Guidelines are also provided for th...


  • JLA Vol:8 Iss:6 (Welding of aluminum: A challenging opportunity for laser technology)

    Friedrich Dausinger
    Ju¨rgen Rapp
    Markus Beck
    Frank Faisst
    Ru¨diger Hack
    Helmut Hu¨gel
    Universita¨t Stuttgart, Institut fu¨r Strahlwerkzeuge (IFSW), Pfaffenwaldring 43, D&hyphen;70569 Stuttgart, Germany

    The increasing demand for lightweight structures has led to a greater industrial use of aluminum alloys. The application of these materials is handicapped by a lack of productivity and reliability in the joining techniques currently available. The laser welding of aluminum is markedly more difficult than for steel. The difficulties to be solved include the threshold for deep penetration welding...


  • JLA Vol:9 Iss:1 (Characteristics of CO<sub>2</sub> laser welded high carbon steel gauge plate)

    Eng S. Ng
    Ian A. Watson
    Laser and Optical System Engineering Center, Department of Mechanical Engineering, James Watt Building, University of Glasgow, Glasgow G12 8QQ, U.K.

    The welding performance of CO2 lasers is strongly affected by the clamping geometry and welding speed. Moreover, the rapid cooling rate associated with laser welding results in an untempered martensitic structure and a transverse variation in the hardness profile. An untempered martensitic structure can lead to brittle welds, and particularly for samples that are subject to cyclic loading, component fatigue and failure. To avoid this problem it is useful to optimize the laser operat...


  • JLA Vol:9 Iss:1 (Continuous wave Nd:YAG laser cladding modeling: A physical study of track creation during low power processing)

    J&hyphen;.M. Jouvard
    D. F. Grevey
    F. Lemoine
    A. B. Vannes

    This paper concerns the modeling of cladding using an Nd:YAG laser operating at low powers typically less than 800 W. Experimental observation of the evolution of the mass of the clads shows two power thresholds. The theoretical study relies on a calculation of the fluence provided to the substrate and on a model of heat transfer into the substrate. We suggest that the first threshold is the power required for substrate melting. The second power is the threshold when the powder is directly melted by the beam and is therefore a liquid when contacting the substrate.


  • JLA Vol:9 Iss:1 (Laser cladding of Al&hyphen;Sn alloy on a mild steel)

    Z. Liu
    J. L. Sun
    W. M. Steen
    K. G. Watkins
    C. Lee
    W. P. Brown

    Direct laser cladding of Al alloy on mild steel produces continuous brittle intermetallic FexAly layers at the interface resulting in weak bonding of the clad and the substrate. To overcome this problem, both Ni and Al were investigated as intermediate coatings. Although a Ni coating with a thickness of 70 μm was successful in eliminating the formation of continuous Al&hyphen;Fe intermetallics, the bonding at the Al alloy/Ni interface was not strong enough to survive a bending test. A pure Al coating was found to be a better ...


  • JLA Vol:9 Iss:1 (Laser generated air contaminants released during laser cutting of fabrics and polymers)

    Max Kiefer
    C. Eugene Moss
    National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH 45226, U.S.A.

    Environmental monitoring was conducted at an industrial facility to qualitatively identify the major contaminants generated while cutting fabrics and polymers with a 25 W CO2 continuous beam laser. Carbon monoxide, hydrogen cyanide, and particulates were also assessed, and a bulk sample of residue from the laser exhaust duct was analyzed for inorganic acids, pH, and volatile organic compounds. Samples were collected while cutting vinyl, acrylics, woven fabrics, felt, Formica®, and Plexiglass®....