JLA Vol:18 Iss:4 (Threshold powers and delays for igniting propane and butane-air mixtures by cw laser-heated small particles)

Authors:
Thomas H. Dubaniewicz
National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory, 626 Cochrans Mill Road, Pittsburgh, Pennsylvania 15236

The National Institute for Occupational Safety and Health, Pittsburgh Research Laboratory conducted a study of laser safety in potentially flammable environments. Researchers measured threshold igniting powers as a function of beam diameter for butane and propane-air mixtures by laser-heating targets placed on optical fiber tips using a 1064 nm laser. The minimum igniting powers for propane-air and butane-air were about 250 and 300 mW, respectively. Threshold igniting powers for propane-air were approxima...

JLA Vol:23 Iss:4 (Thermal diffusivity measurement of silver nanofluid by thermal lens technique)

Authors:
Reza Zamiri
Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

B. Z. Azmi
Department of Physics,Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia and Advanced Materials and Nanotechnology Laboratory, Institute of Advanced Technology, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

E. Shahriari
Kazim Naghavi
E. Saion
Zahid Rizwan
M. S. Husin
Department of Physics, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

The thermal lens technique was utilized in silver nanofluid containing silver nanopartic...

JLA Vol:6 Iss:1 (Amending the CDRH performance standard for laser products)

Authors:
Jerome E. Dennis
Office of Compliance and Surveillance Center for Devices and Radiological Heath, US Food and Drug Administration, Silver Springs, MD, U.S.A.

The most recent amendments to the Federal performance standard for laser products became effective in 1985 and 1986. At this time, the Center for Devices and Radiological Health (CDRH) is making public its intention to amend the standard again and is inviting suggestions and comments. The amendments that are now under consideration are based upon advances in the sciences of photobiology and hazard evaluation. They are also intended to harmonize with developments in international standards for similar products, and to cla...

JLA Vol:17 Iss:2 (Feedback control effects on dimensions and defects of H13 tool steel by direct metal deposition process)

Authors:
Y. Hua
J. Choi
Department of Mechanical and Aerospace Engineering and Engineering Mechanics, University of Missouri, Rolla, Missouri 65409-1060

As a promising and novel manufacturing technology, laser aided direct metal deposition (DMD) process produces near-net-shape functional metal parts directly from the computer aided design (CAD) model. In-process feedback control has been recognized as a critical element to ensure the dimensional accuracy as well as near-net-shape production. Furthermore, process parameters should be delicately controlled to produce defect-free parts with superior mechanical properties. A closed loop real-time optical height control system...

JLA Vol:25 Iss:5 (Investigation into the effects of process parameters on bending angle in the laser bending of tailor machined blanks based on a statistical analysis)

Authors:
Mehdi Safari
Mahmoud Farzin
Abbas Ghaei
Department of Mechanical Engineering, Isfahan University of Technology, Isfahan 84156-83111, Iran

In this paper, the effects of process parameters on bending angle in laser bending of tailor machined blanks are investigated experimentally. The Taguchi experimental design method is employed to study various parameters, which significantly affect the bending angle in the laser bending of tailor machined blanks. The start point of scan path, irradiating method, laser output power, beam diameter, and number of radiation passes are considered in the evaluations. A L₁₈(2¹×3⁴) Ta...

JLA Vol:21 Iss:4 (Numerical model of a laser-sustained argon plasma)

Authors:
R. Akarapu
A. R. Nassar
Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802-6812

S. M. Copley
Applied Research Laboratory and Department of Mechanical and Nuclear Engineering, Penn State University, University Park, Pennsylvania 16802-6812

J. A. Todd
Department of Engineering Science and Mechanics, Penn State University, University Park, Pennsylvania 16802-6812

A steady state axi-symmetric model was developed to predict the size, shape and temperature of a laser-sustained plasma in flowing argon. The power of the carbon dioxide (CO₂) laser and the free s...

JLA Vol:8 Iss:3 (Theoretical and experimental studies of thick‐section cutting with a chemical oxygen–iodine laser (COIL))

Authors:
A. Kar
J. E. Scott
W. P. Latham

A simple mathematical model of thick‐section stainless steel cutting with a high power chemical oxygen–iodine laser (COIL) is presented and compared with experimental results obtained with a 10‐kilowatt COIL at the U.S. Air Force's Phillips Laboratory. This model uses a lumped‐parameter technique to relate the cutting kerf depth with various process parameters and can be used to predict scaled laser materials processing performance to very thick sections. The model is similar to an empirical model developed by researchers in Japan, but includes predictive capabilities for thick metal cutting...

JLA Vol:2 Iss:3 (Current State‐of‐the‐Art of Contouring Techniques in Manufacturing)

Authors:
Kevin G. Harding
Industrial Technology Institute, Sensor Center for Improved Quality, Ann Arbor, Michigan 48106

A manager with a major automobile manufacturer once made the comment that “the best thing we ever did to improve quality was give the guys on the floor a caliper to measure the parts”. As the tolerances on manufacturing become tighter, the need for accurate measurement has also increased. Hand fitting of parts to each other does not work in modern automated factories. Gauges in the past have been built to provide a fixed set of measurements of a known part. This practice too has been changing due to the trend toward flexible manufacturing. Now the gages...

JLA Vol:15 Iss:3 (Preparation of polyperinaphthalenic organic semiconductive nanoparticles by excimer laser ablation and their application to optic and electronic devices)

Authors:
Satoru Nishio
Hiroshi Fukumura
Department of Chemistry, Graduate School of Science, Tohoku University, Aramaki, Sendai, Miyagi 980-8578, Japan

Kazuyuki Tamura
Jun Murata
Junko Kitahara
Teruhiko Kan
Akiyoshi Matsuzaki
Department of Chemistry for Materials, Faculty of Engineering, Mi’e University, 1515 Kamihama-cho, Tsu, Mi’e 514-8507, Japan

Nobuo Ando
Yukinori Hato
Kanebo LTD., 3-1, Kanebo-cho, Hofu, Yamaguchi 747-0823, Japan

Polyperinaphthalene (PPN) nanoparticles are prepared by excimer laser ablation (ELA) of a 3, 4, 9, 10-perylenetetracarbox...

JLA Vol:1 Iss:4 (Laser Accidents: Are They All Reported and What Can Be Learned from Them?)

Authors:
R. James Rockwell
Rockwell Laser Industries, Cincinnati, Ohio