JLA Vol:23 Iss:1 (Modeling the selective laser melting of polylactide composite materials)

Authors:
Christian Morsbach
Chair for Laser Technology, RWTH Aachen University, Steinbachstraße 15, 52074 Aachen, Germany

Simon Ho¨ges
Wilhelm Meiners
Fraunhofer Institute for Laser Technology, Steinbachstraße 15, 52074 Aachen, Germany

The rapid manufacturing technology selective laser melting (SLM) is among others employed to build individually designed bone implants out of the bioresorbable composite material polylactide/β-tricalcium phosphate (PDLLA/β-TCP). Degradation of PDLLA, which commences at temperatures >215 °C and results in unwanted changes in resorption kinetics, has to be avoided. This is achieved by keepin...

JLA Vol:23 Iss:1 (Optimal process parameters for thermoplastic polyetheretherketone joints fabricated using transmission laser welding and Lumogen^® IR absorptive pigment)

Authors:
Negin Amanat
School of Physics, University of Sydney, New South Wales 2006, Australia and Cochlear Ltd., 14 Mars Rd., Lane Cove, New South Wales 2066, Australia

Cedric Chaminade
John Grace
Raymax Applications, P.O. Box 958, Newport Beach, New South Wales 2106, Australia

Natalie L. James
Cochlear Ltd., 14 Mars Rd., Lane Cove, New South Wales 2066, Australia

David R. McKenzie
School of Physics, University of Sydney, New South Wales 2006, Australia

This study investigates the effects of the process parameters (laser power and irradiation time) on the bond quality of transmission laser welded polyether...

JLA Vol:23 Iss:1 (Picosecond laser-induced color centers in glass optics)

Authors:
David Ashkenasi
Andreas Lemke
Applied Laser Technology, Laser- and Medical-Technology Berlin (LMTB) GmbH, Fabeckstr. 60-62, 14195 Berlin, Germany

It is known that ionizing radiation (x ray, gamma rays, and electrons) can induce numerous changes in the physical properties of glasses. The most obvious effect is visible coloration, which is caused by the accumulation of color centers (defects) in the irradiated volume. The application of such induced color centers has prompted a renewed interest since they can be generated and bleached reversibly. We present results on laser-induced color centers in different types of glasses using picosecond laser pulses. By applyi...

JLA Vol:23 Iss:1 (Review of laser microscale processing of silicon carbide)

Authors:
B. Pecholt
S. Gupta
P. Molian
Department of Mechanical Engineering, Laboratory for Lasers, MEMS and Nanotechnology, Iowa State University, Ames, Iowa 50011

A review of various laser techniques for microscale processing of SiC for microelectronics and microelectromechanical-system applications is presented. SiC is an excellent material for harsh environments due to its outstanding mechanical, thermal, and chemical properties. However, its extreme thermodynamic stability and inert properties created difficulties in conventional microfabrication methods which provided an opportunity for the exploration of laser processing as an alternative. Many aspects...

JLA Vol:23 Iss:1 (Tolerances of joint gaps in Nd:YAG laser welded Ti-6Al-4V alloy with the addition of filler wire)

Authors:
X. Cao
Aerospace Manufacturing Technology Centre, Institute for Aerospace Research, National Research Council Canada, 5145 Decelles Ave., Montreal, Quebec H3T 2B2, Canada

G. Debaecker
Ecole Centrale de Nantes, 1 Rue de la Noe´, B.P. 92101, 44321 Nantes Cedex 3, France

E. Poirier
Aerospace Manufacturing Technology Centre, Institute for Aerospace Research, National Research Council Canada, 5145 Decelles Ave., Montreal, Quebec H3T 2B2, Canada

S. Marya
Ecole Centrale de Nantes, 1 Rue de la Noe´, B.P. 92101, 44321 Nantes Cedex 3, France

J. Cuddy
A. Birur
Standard Aero Limited, 33 Allen D...

JLA Vol:23 Iss:2 (Automatic real-time guidance of laser machining with inline coherent imaging)

Authors:
Paul J. L. Webster
Logan G. Wright
Kevin D. Mortimer
Ben Y. Leung
Joe X. Z. Yu
James M. Fraser
Department of Physics, Engineering Physics and Astronomy, Queen's University, Kingston, Ontario K7L 3N6, Canada

Optical coherence imaging can measure hole depth in real-time (>20 kHz) during laser drilling without being blinded by intense machining light or incoherent plasma emissions. Rapid measurement of etch rate and stochastic melt relaxation makes these images useful for process development and quality control in a variety of materials including metals, semiconductors, and dielectrics. The ability to image th...

JLA Vol:23 Iss:2 (Comprehensive predictive modeling and parametric analysis of multitrack direct laser deposition processes)

Authors:
Shaoyi Wen
Yung C. Shin
Center for Laser-Based Manufacturing, School of Mechanical Engineering, Purdue University, West Lafayette, Indiana 47907

Direct laser deposition is a very useful method of fabricating complex parts directly from CAD drawings. Despite its usefulness, many parameters that affect the final quality of the fabricated part make the selection of optimal operating conditions difficult. In this paper, new comprehensive numerical modeling is presented to describe the underlying physics in multitrack direct laser deposition processes including laser powder interaction, mass addition, fluid motion, melting, and solidification. The model rigorously con...

JLA Vol:23 Iss:2 (Effect of atmosphere above specimen on welding results during remote welding)

Authors:
Shinpei Oiwa
Yousuke Kawahito
Masami Mizutani
Seiji Katayama
Joining and Welding Research Institute (JWRI), Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka 567-0047, Japan

Remote welding has already been applied in the automobile industry [S. Ream, Proceedings of the 69th Laser Materials Processing Conference, Tokyo, Japan, 2007, pp. 1–14: M. H. Rhee et al., Proceedings of the 68th Laser Materials Processing Conference, Osaka, Japan, 2007, pp. 141–146), owing to many advantages. The authors revealed that the weld bead changed from full to partial penetration during remote welding of a steel sheet at the focal position withou...

JLA Vol:23 Iss:2 (Experimental investigation of laser shock peening using femtosecond laser pulses)

Authors:
Dongkyun Lee
Elijah Kannatey-Asibu
Department of Mechanical Engineering, The University of Michigan, Ann Arbor, Michigan 48105-2125

In this study, the feasibility of laser shock peening using ultrafast laser pulses was experimentally investigated. A top coating of zinc with a water confining layer was applied in the investigation. The zinc coating was used for the thermoprotective effect. A high numerical aperture (NA≅0.5) aspheric lens was used to minimize the optical breakdown of water. Microhardness measurements were made on the top surface of the shock peened specimen and compared with the original material hardness. The results provide useful insight on...

JLA Vol:23 Iss:2 (Microcomputed tomography analysis of intralayer porosity generation in laser direct metal deposition and its causes)

Authors:
M. Naveed Ahsan
Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester M13 9PL, United Kingdom

Robert Bradley
Henry Moseley X-ray Imaging Facility, School of Materials, University of Manchester, Grosvenor Street, Manchester M13 9PL, United Kingdom

Andrew J. Pinkerton
Laser Processing Research Centre, School of Mechanical, Aerospace and Civil Engineering, University of Manchester, Sackville Street, Manchester M13 9PL, United Kingdom

Laser direct metal deposition has wide application in the areas of rapid manufacturing, surface coating, and compon...