Authors:
A. A. Peligrad
E. Zhou
D. Morton
Faculty of Technology, Bolton Institute, Deane Road, Bolton BL3 5AB, United Kingdom

L. Li
Laser Processing Research Centre, Department of Mechanical Engineering, UMIST, Sackville Street, P.O. Box 88, Manchester M60 1QD, United Kingdom




There are many process parameters that influence the results of laser marking of ceramic materials. Some parameters should be kept within certain tolerance limits to ensure the expected quality of the laser processing. Hence a closed loop control system may be desirable during the process for quality control. For this, an accurate multi-input and multioutput dynamic...

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Authors:
Robert J. Thomas
Benjamin A. Rockwell
Air Force Research Laboratory, Brooks AFB, Texas 78235-5215

Wesley J. Marshall
USACHPPM, Aberdeen Proving Ground, Maryland 21010-5422

Robert C. Aldrich
Sheldon A. Zimmerman
Dahlgren Division, Naval Surface Warfare Center, Dahlgren, Virginia 22448-5100

R. James Rockwell
Rockwell Laser Industries, Cincinnati, Ohio 45243




Over the past few years, a comprehensive rewrite of the American National Standard for Safe Use of Lasers (ANSI Z136.1) has been conducted. The ANSI Z136.1 is a user standard, as opposed to a manufacturer standard like the Federal Las...

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Authors:
M. Boutinguiza
F. Lusquin˜os
J. Pou
R. Soto
F. Quintero
M. Pe´rez-Amor
Departamento Fı´sica Aplicada Universidade de Vigo, Lagoas Marcosende 9, E-36200 VIGO, Spain

K. Watkins
Laser Engineering Group, Department of Engineering, The University of Liverpool, Liverpool L69 3GH, United Kingdom




Slate is a natural stone which has the characteristic that shows a well-developed defoliation plane, allowing to easily split it in plates parallel to that plane which are particularly used as tiles for roof building. At present, the manufacturing of slate is mostly manual, bein...

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Authors:
X. Zhou
K. Imasaki
H. Furukawa
C. Yamanaka
Institute for Laser Technology, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan

S. Nakai
Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871, Japan




A high-power pulsed Nd:YAG laser was employed to irradiate a 20-μm-thick Zn coating on a carbon steel surface. The ablation rate was defined as ablated volume divided by consumed laser energy, and was used to assess ablation cleaning ability. The relationships of ablation rate to laser pulse width and ablation rate to laser fluence were investigated, and optimal processing conditions were dete...

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Authors:
J. Du
School of Optics, Center for Research and Education in Optics and Lasers, Mechanical and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816

J. Longobardi
Metal Tech Industries, 525 Lawler Street, Iowa Falls, Iowa 50126

W. P. Latham
Air Force Research Laboratory, Directed Energy Directorate, 3550 Aberdeen Avenue SE, Kirland AFB, New Mexico 87117-5776

A. Kar
School of Optics, Center for Research and Education in Optics and Lasers, Mechanical and Aerospace Engineering Department, University of Central Florida, Orlando, Florida 32816




Butt welding is practically difficult f...

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Authors:
M. H. McCay
J. A. Hopkins
T. D. McCay
The University of Tennessee Space Institute, Center for Laser Applications, Tullahoma, Tennessee 37388




The depth of the melt layer during laser surface alloying plays a significant role in the shape of the melt pool. There appear to be critical depths at which the molten layer becomes unstable and alters its shape in response to convective flow patterns. The Marangoni number provides an understanding of the influence of the material properties on convection and subsequently the melt shape, being inversely proportional to depth squared, viscosity, and thermal diffusivity, and directly proportional to the surface t...

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Authors:
Hyungson Ki
Pravansu S. Mohanty
Jyotirmoy Mazumder
Center for Laser Aided Intelligent Manufacturing, Department of Mechanical Engineering and Applied Mechanics, The University of Michigan, Ann Arbor, Michigan 48109-2125




In laser drilling and keyhole welding, multiple reflection phenomena determine how the energy is transferred from the laser beam to the workpiece, and, most importantly, all other physics such as fluid flow, heat transfer, and the cavity shape itself depend on these phenomena. In this study, a multiple reflection model inside a self-consistent (or self-evolving) cavity has been developed based on the level set method and ray tracing t...

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Authors:
L. M. Lobo
K. Williams
Optical Engineering Group, Wolfson School of Mechanical and Manufacturing Engineering, Loughborough University, Loughborough, Leicestershire LE11 3TU, United Kingdom

E. P. Johnson
Laser Group, Department of Mechanical Engineering, Liverpool University, Liverpool, Merseyside L69 3BX, United Kingdom

J. T. Spencer
BNFL, Rutherford House, Risley, Warrington, Cheshire WA3 6AS, United Kingdom




This article examines the particles formed during optimized laser scabbling of concrete in order to help determine an effective filtration strategy for the process. The laser scabbling technique has been developed ...

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Authors:
Kunio Awazu
Mikio Tanaka
Institute of Free Electron Laser, Osaka University, 2-9-5, Tsudayamate, Hirakata, Osaka 573-0128, Japan

Junji Kato
Department of Pediatric Dentistry, Faculty of Dentistry, Tokyo Medical and Dental-University, Japan




Tuning a laser wavelength to the stretching vibration of specific biomolecules has some advantages in ablating hard tissue and for surface modification induced by the photothermal or the photomechanical interaction. A tunable pulsed transversely excited atmosphere CO2 laser was tuned to 9.45 μm, which is the stretching vibration of phosphoric acid in hydroxyapatite. Dried cow dentine was irra...

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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...

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Authors:
G. Casalino
L. A. C. De Filippis
A. D. Ludovico
L. Tricarico
Dipartimento di Ingegneria Meccanica e Gestionale, Politecnico di Bari, 70126 Bari, Italy




Among the layer fabrication techniques, selective laser sintering (SLS), is widely used for manufacturing various products made of different materials (i.e., polycarbonates, nylons, polyamides, sand casting, metal powders, and others). The SLS of precoated foundry sands allows the aggregation of adjacent particles, which are then cemented by furnace heat treatment. Moreover, geometrically complex molds and cores not obtainable with conventional methods can be realized by this method. In th...

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Authors:
Yoshiaki Shimokusu
Kobe Shipyard & Machinery Works, Mitsubishi Heavy Industries Ltd., 1-1-1 Wadasaki-cho, Hyogo-ku, Kobe Hyogo 652-8585, Japan

Seiji Fukumoto
Kobe Shipyard & Machinery Works, Mitsubishi Heavy Industries Ltd., 1-1-1 Wadasaki-cho, Hyogo-ku, Kobe Hyogo 652-8585, Japan

Michisuke Nayama
Technology Planning Department, Technical Headquarters, Mitsubishi Heavy Industries Ltd., 3-3-1 Minatomirai, Nishi-ku, Yokohama Kanagawa 220-8401, Japan

Takashi Ishide
Takasago R&D Center, Mitsubishi Heavy Industries Ltd., 2-2-1 Shinhama, Arai-cho, Takasago Hyogo 676-8686, Japan

Shuho Tsubota
Takasago...

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Authors:
K. C. Chan
J. Liang
Department of Manufacturing Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong




In this article, the deformation behavior and microstructure of a hardened high carbon steel in laser bending were examined. A CO2 laser unit (TEM00) was used to bend the samples at different laser powers, scanning velocities, and number of scans. A relatively linear relationship between bending angle and number of scans was obtained at laser powers of 150 and 200 W and at a scanning velocity of 30 mm/s. A threshold heat input of about 3.25 J/mm was observed, below which bending was unlikely to occur. The bending angle was al...

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Authors:
Manuela Lualdi
Ambrogio Colombo
Alberto Mari
Stefano Tomatis
Renato Marchesini
Medical Physics Unit, Istituto Nazionale per lo Studio e la Cura dei Tumori, Milan, Italy




Realistic, pigmented skin simulants (“phantoms”) can be useful in optimizing dermal laser procedures and for laser surgical training. Diffuse reflectance of skin pigmented lesions depends on the amount and distribution of the absorbing/diffusing chromophores, mainly hemoglobin and melanin, embedded in the skin layers. The reason why diffuse reflectance of benign melanocytic lesions is different from that of melanoma is still unclear. In an attempt...

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Authors:
H. Gedda
Luleå University of Technology, Division of System and Manufacturing Engineering, S-971 87 Luleå, Sweden

J. Powell
Laser Expertise Ltd., Acorn Park Industrial Estate, Harrimans Lane, Nottingham NG7 2TR, United Kingdom

G. Wahlstro¨m
Duroc AB, Industriva¨gen 8, S-90130 Umeå, Sweden

W.-B. Li
H. Engstro¨m
C. Magnusson
Luleå University of Technology, Division of System and Manufacturing Engineering, S-971 87 Luleå, Sweden




This article examines the factors that effect the efficiency of the CO2-laser powder cladding process. By the...

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Authors:
Rick Mannix
Environmental Health & Safety Office, University of California, Irvine, California 92697-2725




While training, engineering controls, warning signs/systems, and protective eyewear are emphasized in laser safety programs, laser-related accidents do occur in facilities without obvious deficiencies in those areas. Problems still occur because of insufficient attention to administrative safety issues directly related to human nature and behavioral factors. Common safety problems associated with behavioral factors are discussed. Personal experiences of the author, including lessons learned, are included. The issues are discussed within the context of laser safety, bu...

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Authors:
Kazuhiko Ono
Kaoru Adachi
Manufacturing Engineering Development Center, Komatsu Ltd., Hirakata, Osaka 573-1011, Japan

Isamu Miyamoto
Takashi Inoue
Department of Manufacturing Science, Osaka University, Suita, Osaka 565-0871, Japan




The influence of oxide film, such as laser cutting edge or mill scale, on CO2 laser welding phenomena and weld characteristics of mild steel was investigated. Laser welding of butt joints, which were different in location and thickness of oxide film, were performed. Examinations were made on the weld characteristics which were: bead geometry, defect, and microstructure. Light emitted from la...

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Authors:
Allen Sun
Elijah Kannatey-Asibu
Department of Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan 48109

Mark Gartner
Ford Motor Company, Dearborn, Michigan 48121




Depth of penetration is a critical parameter in laser welding. In many applications, full penetration is desired, but difficult to detect in real time. A sensor fusion system using infrared, ultraviolet, audible sound, and acoustic emission has been implemented for real time monitoring of CO2 laser lap welds in both laboratory and industrial production settings. Signals from the welds were analyzed by: (1) singular value decomposition with data fusion,...

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Authors:
J. Lawrence
L. Li
Department of Mechanical Engineering, Laser Processing Research Centre, Manufacturing Division, University of Manchester Institute of Science and Technology (UMIST), Manchester M60 1QD, United Kingdom




This work elucidates and analyzes the factors responsible for modifications to the wettability characteristics of metallic materials after high power diode laser (HPDL) treatment. It was found that interaction of EN3 and EN8 mild steel with HPDL radiation resulted in the wettability characteristics of the mild steels altering to various degrees depending upon the laser processing parameters. Such changes in the wettability characteristics of the mi...

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Authors:
Yonggang Li
School of Optic/CREOL (Center for Research and Education of Optics and Lasers), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida, 32816-2700

Nathaniel R. Quick
USF Filtration and Separations Group, Inc., 1750 Filter Drive, DeLand, Florida 32724-2045

Aravinda Kar
School of Optic/CREOL (Center for Research and Education of Optics and Lasers), Mechanical, Materials and Aerospace Engineering Department, University of Central Florida, Orlando, Florida, 32816-2700




A new dieless metal fiber drawing process is developed in which a high-precision laser is used to heat the...

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




This article addresses experimental-based modeling of the powder injection laser cladding process. An accurate model for the process is essential for controller design and process automation. There are few dynamic and static models for the process, however, due to the limitations and intensive numerical calculations, their application to real-time process control are not practical. Two model structures, the Hammerstein–Wiener model and Elman recurrent neural network are implemented to identify the laser cl...

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Authors:
S. S. Kudesia
Department of Physics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom

P. Solana
Departamento de Matema´tica Aplicada, Universidad Polite´cnica de Madrid, Spain

W. S. O. Rodden
D. P. Hand
J. D. C. Jones
Department of Physics, Heriot-Watt University, Riccarton, Edinburgh EH14 4AS, United Kingdom




The significance of melt ejection during various drilling regimes of laser drilling is investigated. The predictions of two analytical models of the drilling process, with and without the melt ejection mechanism, are compared with experimental measurements made using a ...

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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...

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Authors:
J. Tu
School of Industrial Engineering, Purdue University, West Lafayette, Indiana 47907

I. Miyamoto
T. Inoue
Department of Manufacturing Science, Osaka University, Osaka, Japan




In very deep penetration, the plasma inside the keyhole exhibits complicated behavior and the plasma plume covering outside the keyhole can also affect the observation of keyhole plasma. Measuring the light emission from keyhole plasma is an effective method to monitor laser welding processes in thin sheets; however, in welding thick sheets, several critical phenomena must be observed. In this article, we provide experimental investigations using a 20 kW CO2

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Authors:
Hussein A. Abdullah
School of Engineering, University of Guelph, Guelph, Ontario N1G 2W1, Canada

Chris R. Chatwin
School of Engineering, University of Sussex, Brighton BN1 9QT, United Kingdom




This article reports results from an experimental investigation into laser welding of ferromagnetic material, which, for example, is of interest to the European Space Agency. The effects of laser welding power and translation velocities on the magnetism of ferromagnetic materials were studied. An automated system using a Hall effect transducer was constructed to measure the magnetic field transverse to the laser weld before welding, immediately after welding and thr...

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