JLA Vol:6 Iss:2 (CO₂ 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‐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...

JLA Vol:14 Iss:1 (Physical–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...

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...

JLA Vol:8 Iss:3 (Laser Hardened Materials Evaluation Laboratory (LHMEL))

Authors:
R. J. Hull
M. L. Lander

Since 1976, the Laser Hardened Materials Evaluation Laboratory (LHMEL) has been characterizing material responses to laser energy in support of national defense programs and the aerospace industry. Now that capability is available to commercial industry as well. LHMEL's power levels, beam uniformity, and diagnostics capabilities make it an ideal facility for proof‐of‐concept testing or process development. Located at Wright‐Patterson Air Force Base, Ohio, LHMEL is managed by the Wright Laboratory Materials Directorate and operated by Lawrence Associates, Incorporated. The facility's advanced hardware is centered aroun...

JLA Vol:2 Iss:2 (Binary Phase Gratings for Materials Processing)

Authors:
Paul J. Patt
Array

The feasibility of using a diffractive optical element, a phase grating, as a beam handling device for use in industrial laser material processing is examined. The binary phase grating is an efficient beam splitting device and is useful in many materials processing operations (welding, cutting, soldering, drilling) where a high degree of parallelism could significantly improve process throughput. Overall efficiency of etched quartz binary gratings agrees well with published predictions (nominal 70–90%). Copies of the grating formed in PMMA (acrylic) survived preliminary life tests (more than 1000 9‐J pulses from a commercial multimode N...

JLA Vol:16 Iss:3 (Solidification model of laser cladding with wire feeding technique)

Authors:
Chien-Fu Hung
Jehnming Lin
Department of Mechanical Engineering, National Cheng Kung University, Tainan 701, Taiwan

The object of this study is to investigate the solidification problem in laser cladding with the wire feeding technique. The solidification phenomenon of laser cladding was analyzed by numerical simulation and experimental visualization. Good agreement has been obtained for 304 stainless steel wires cladding on round tubes and it transpires that there were three basic modes of clad profiles: thinning, thickening, and wavering of the clad thickness at different velocity settings between the feeding wire and the substrate in laser wire cladding. &copy...

JLA Vol:20 Iss:4 (Laser cutting of 2024-T3 aeronautic aluminum alloy)

Authors:
A. Riveiro
F. Quintero
F. Lusquin˜os
J. Pou
M. Pe´rez-Amor
Departamento de Fi´sica Aplicada, Universidade de Vigo, ETS Ingenieros Industriales, Vigo, 36310, Spain

Since the beginning of the aeronautic industry, aluminum alloys have played a crucial role in its development. Nowadays, different aluminum alloy families are the base material of many pieces of aerospace vehicles. In this work, a novel approach to process aluminum alloys is explored. The authors efforts are aimed to cut 2024-T3 plates by a CO₂ laser. They used a novel laser cutting head assisted by a gas jet working in supersonic regim...

JLA Vol:25 Iss:1 (Implementation of a novel scan localization system for wireless sensor networks)

Authors:
K. Sun
W. Huang
Sachula Meng
Y. Xiao
M. T. Wang
Z. Xiao
Inner Mongolia University, Hohhot 010021, China

A novel localization scheme called laser beam scan localization by combining grid and light (laser) with mobile localization policy for wireless sensor networks is designed. The scheme utilizes a moving location assistant (LA) with a laser beam, through which the deployed area is scanned. The LA sends identities to unknown nodes to obtain the locations of sensor nodes. High localization accuracy can be achieved without the aid of expensive hardware on the sensor nodes, as required by other localization systems...

JLA Vol:24 Iss:4 (Laser-assisted nanofabrication of carbon nanostructures)

Authors:
Yun Shen Zhou
Wei Xiong
Jongbok Park
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, USA

Min Qian
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska, 68588-0511, USA and Department of Physics, East China Normal University, Shanghai 200062, People’s Republic of China

Masoud Mahjouri-Samani
Yang Gao
Department of Electrical Engineering, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0511, USA

Lan Jiang
Department of Mechanical and Automation Engineering, Beijing Institute of Technology, Bei...

JLA Vol:5 Iss:1 (Heat Flow in Laser Die Blank Welding)

Authors:
Y.‐S. Yang
C. R. Hsu
C. E. Albright
Y. Kuroda

Laser welded die blanks are finding increased usage in many industrial applications. This investigation was undertaken to establish a simplified means of calculating thermal cycles experienced in the fusion and heat affected zones on laser welds typically used in die blank welding. A planar solution domain perpendicular to the direction of travel was selected to simplify the finite element calculations. The resulting calculation technique provided reasonably accurate prediction of the thermal cycles measured by Moon and Metzbower, and the size of fusion zones and heat affected zones o...