JLA Vol:25 Iss:5 (Heat transfer and fluid flow in additive manufacturing)

Authors:
A. Raghavan
H. L. Wei
T. A. Palmer
T. DebRoy
Department of Materials Science and Engineering, Pennsylvania State University, University Park, Pennsylvania 16802

In laser-based direct energy deposition additive manufacturing, process control can be achieved through a closed loop control system in which thermal sensing of the melt pool surface is used to adjust laser processing parameters to maintain a constant surface geometry. Although this process control technique takes advantage of important in-process information, the conclusions drawn about the final solidification structure and mechanical properties of the deposited material are li...

JLA Vol:25 Iss:5 (Stoichiometric 6H-SiC thin films deposited at low substrate temperature by laser ablation)

Authors:
J. G. Quin˜ones-Galva´n
Physics Department, CINVESTAV-IPN, Apdo. Postal 14-740 Me´xico, D.F. 07360, Mexico

J. S. Arias-Cero´n
CICATA-IPN, Unidad Legaria, Me´xico D.F. 11500, Mexico

F. de Moure-Flores
Facultad de Qui´mica, Materiales, Universidad Auto´noma de Quere´taro, Quere´taro 76010, Mexico

A. Herna´ndez-Herna´ndez
A. Guille´n-Cervantes
J. Santoyo-Salazar
J. G. Mendoza-Alvarez
M. Mele´ndez-Lira
Physics Department, CINVESTAV-IPN, Apdo. Postal 14-740 Me´xico, D. F. 07360, Mexico


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JLA Vol:25 Iss:5 (Review study on remote laser welding with fiber lasers)

Authors:
Jinhong Lu
ABB Electrical Machines Ltd, Shanghai, China, 200245

Veli Kujanpa¨a¨
VTT Technical Research Centre of Finland, Lappeenranta, Finland, 53850

The appearance of the high-power fiber laser with brilliant beam quality enables a rapid development of remote laser welding (RLW). In this paper, a theoretical study of remote laser welding has been reviewed. As a promising technology, the RLW offers an increased flexibility, high operational speed, and reduced cycle time to process a wide range of workpieces. This study presents the feasibility and typical characteristics of RLW with high-power fiber lasers. Meanwhile, the influence of process pa...

JLA Vol:25 Iss:5 (Femtosecond laser post-processing of metal parts produced by laser additive manufacturing)

Authors:
Ilya Mingareev
Tobias Bonhoff
Ashraf F. El-Sherif
Townes Laser Institute, CREOL, University of Central Florida, Orlando, Florida 32816

Wilhelm Meiners
Ingomar Kelbassa
Fraunhofer Institute for Laser Technology, Aachen 52074, Germany

Tim Biermann
Joining Technologies Research Center, East Granby, Connecticut 06026

Martin Richardson
Townes Laser Institute, CREOL, University of Central Florida, Orlando, Florida 32816

High-repetition rate femtosecond laser radiation was utilized to improve surface quality of metal parts manufactured by laser additive techniques. Different lase...

JLA Vol:25 Iss:5 (Crack-free laser dicing of glass in the microelectronics industry)

Authors:
Guillaume Savriama
GREMI-UMR 7344, CNRS/Universite´ d'Orle´ans, 14 rue d'Issoudun, BP 6744, F-45067 Orle´ans cedex 2, France and STMicroelectronics, 10 rue de Thalès de Milet, CS 97155, 37071 Tours Cedex 2, France

Jose´ Mendez
Laurent Barreau
STMicroelectronics, 16 rue Pierre et Marie Curie, BP 7155, F-37071 Tours Cedex2, France

Chantal Boulmer-Leborgne
Nadjib Semmar
GREMI-UMR 7344, CNRS/Universite´ d'Orle´ans, 14 rue d'Issoudun, BP 6744, F-45067 Orle´ans cedex 2, France

This paper investigates laser dicing of glass (commercial Borofloat

JLA Vol:26 Iss:1 (Evolution of nano-ripples on stainless steel irradiated by picosecond laser pulses)

Authors:
Bin Liu
Wenjun Wang
Gedong Jiang
Xuesong Mei
Kedian Wang
Jiuhong Wang
Zibao Wang
State Key Laboratory for Manufacturing System Engineering, Xi'an Jiaotong University, Xi'an 710054, China

The characteristics of laser-induced periodic surface structures are investigated after laser irradiation with a pulse duration (10 ps) under a certain laser fluence (0.27 J/cm²) and pulse number (N = 50–2000). In the experiments, at the lowest number of pulses, ultrafine ripples are observed with sub-200-nm spatial periods and an orientation parallel to laser polarization ...

JLA Vol:26 Iss:1 (Microstructure characterization and mechanical properties of laser-welded copper and aluminum lap joint)

Authors:
Zhiqing Xue
Shengsun Hu
Junqi Shen
Di Zuo
School of Materials Science and Engineering, Tianjin University, Tianjin 300072, China

Elijah Kannatey-Asibu
Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109-2125

The microstructure in the intermediate layer of a laser-welded Cu–Al lap joint was examined metallographically. Tensile shear test was performed, and fracture surface analysis was also performed using scanning electron microscopy with energy dispersive spectroscopy. Results showed that there were several different zones with diverse characteristics of morphology and comp...

JLA Vol:26 Iss:1 (Geometrical aspects of hot cracks in laser-arc hybrid welding)

Authors:
Greger Wiklund
Department of Applied Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

Odd Akselsen
SINTEF Materials and Chemistry, P. O. Box 4760 Sluppen, NO-7465 Trondheim, Norway

Arve J. So&slash;rgjerd
Kvaerner Verdal AS, Material Department, Hamnevegen 7, NO-7650 Verdal, Norway

Alexander F. H. Kaplan
Department of Applied Sciences and Mathematics, Luleå University of Technology, SE-971 87 Luleå, Sweden

Hot cracks were frequently found in double sided laser-arc hybrid welding thick section (20 mm) low carbon steel. Other research has usually investigat...

JLA Vol:26 Iss:1 (Investigation on reducing distortion by preheating during manufacture of aluminum components using selective laser melting)

Authors:
Damien Buchbinder
Wilhelm Meiners
Norbert Pirch
Konrad Wissenbach
Fraunhofer Institute for Laser Technology (ILT), Aachen 52074, Germany

Johannes Schrage
Chair for Laser Technology, RWTH Aachen University, Germany 52024, Aachen

The additive manufacturing process selective laser melting (SLM) can be used to directly produce functional components made out of metal. During the construction process, however, thermally induced residual stress occurs due to the layered build-up and the local input of energy by means of a focused laser beam, which can lead to distortion of the component or sections of the component itself....

JLA Vol:26 Iss:1 (Performance enhancement of aluminum infrared laser welding by preconditioning with nanosecond laser pulses)

Authors:
Philipp von Witzendorff
Anas Moalem
Uwe Stute
Ludger Overmeyer
Laser Zentrum Hannover e.V., Hollerithallee 8, 30419 Hannover, Germany

We condition the welding zone of the aluminum surface with nanosecond laser pulses prior to welding with infrared laser radiation to increase the process efficiency and weld quality. The high reflectivity of aluminum for infrared laser radiation (95% at 1064 nm) leads to poor process efficiency of aluminum laser welding processes. To increase the workpiece's absorptivity, the welding zone is conditioned with nanosecond laser pulses at a wavelength of 532 nm. The samples are nonalloy, 0.5 mm thick alum...