JLA Vol:9 Iss:1 (Continuous wave Nd:YAG laser cladding modeling: A physical study of track creation during low power processing)
Authors:
J‐.M. Jouvard
D. F. Grevey
F. Lemoine
A. B. VannesThis paper concerns the modeling of cladding using an Nd:YAG laser operating at low powers typically less than 800 W. Experimental observation of the evolution of the mass of the clads shows two power thresholds. The theoretical study relies on a calculation of the fluence provided to the substrate and on a model of heat transfer into the substrate. We suggest that the first threshold is the power required for substrate melting. The second power is the threshold when the powder is directly melted by the beam and is therefore a liquid when contacting the substrate.
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JLA Vol:9 Iss:1 (The development of a laser machining curriculum: An interdisciplinary approach (the MAST program))
Authors:
Gary J. Masciadrelli
Nicholas M. MassaThe development of an industry‐driven interdisciplinary curriculum in laser machining is presented. The Machine tool Advance Skills Technology (MAST) program is a US Department of Education grant to develop and demonstrate a national training model for new technologies and manufacturing processes in precision manufacturing. Springfield Technical Community College (STCC) in partnership with six other community colleges nationwide, developed, tested, and disseminated industry‐specific skills standards and model curricula in laser machining and related technologies for the United States machine tool industry. STC...
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JLA Vol:9 Iss:1 (Laser generated air contaminants released during laser cutting of fabrics and polymers)
Authors:
Max Kiefer
C. Eugene Moss
National Institute for Occupational Safety and Health, Centers for Disease Control and Prevention, Cincinnati, OH 45226, U.S.A.Environmental monitoring was conducted at an industrial facility to qualitatively identify the major contaminants generated while cutting fabrics and polymers with a 25 W CO2 continuous beam laser. Carbon monoxide, hydrogen cyanide, and particulates were also assessed, and a bulk sample of residue from the laser exhaust duct was analyzed for inorganic acids, pH, and volatile organic compounds. Samples were collected while cutting vinyl, acrylics, woven fabrics, felt, Formica®, and Plexiglass®....
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JLA Vol:9 Iss:2 (Kinematic compensation of repetitive errors for non‐circular laser shaping)
Authors:
P. Sheng
K. Liu
Department of Mechanical Engineering, University of California, Berkeley, CA, U.S.A.This paper presents an approach for kinematic compensation of the laser shaping process which is capable of achieving improved dimensional accuracy for non‐circular profiles. In this approach, a plug‐in repetitive controller is added into the existing position servo loop to improve tracking of the desired sinusoidal trajectory and subsequently reduce tracking errors. The effect of tracking errors on different dimensional error modes in the non‐circular shaping process is identified. Simulation models are developed for testing the performance o...
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JLA Vol:9 Iss:2 (Laser cladding with a pulsed Nd:YAG laser and optical fibers)
Authors:
M. Brandt
D. A. Scott
S. B. Emms
J. M. YellupA new laser cladding technique for producing wear and corrosion resistant surfaces on engineering components is reported. The technique involves the combination of the pre‐placed and injected powder delivery methods for producing clad layers. The clad layers were formed with a pulsed Nd:YAG laser and optical fibers. The results using a nickel‐based alloy (Hastelloy C) indicate that uniform clad layers in excess of 1 mm in thickness can be achieved in a single pass with 240 W average power incident on the workpiece. The laser beam was delivered through a step‐index glass ...
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JLA Vol:9 Iss:2 (Temperature‐dependent absorptivity and cutting capability of CO<sub>2</sub>, Nd:YAG and chemical oxygen–iodine lasers)
Authors:
J. Xie
A. Kar
J. A. Rothenflue
W. P. LathamThe most widely used high power industrial lasers are the Nd:YAG and CO2 lasers. The chemical oxygen iodine laser (COIL), whose wavelength (1.315 μm) is between that of the Nd:YAG (1.06 μm) and CO2 (10.6 μm) lasers, is another high power laser for industrial applications. The cutting capability of these lasers is investigated in this paper. The cut depth strongly depends on the absorptivity of the cut material, kerf width and cutting speed. The absorptivity is an unknown parameter for which experimental data at high temperatures are currently unavailable. Theoret...
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JLA Vol:9 Iss:2 (Relationship between airborne acoustic and optical emissions during laser welding)
Authors:
D. Farson
Y. Sang
A. Ali
Department of Industrial, Welding and Systems Engineering, Ohio State University, Columbus, OH, 43210 U.S.A.This paper describes experimental work directed at understanding the relationship between acoustic and optical emissions from the laser welding process. Laser welds were performed and the emissions were measured with a microphone and photodiode and recorded with a data acquisition system. A time‐domain correlation analysis of the acoustic and optical signals revealed them to be highly related at a phase shift corresponding to the delay time for sound to propagate from the weld area to the microphone. A moving av...
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JLA Vol:9 Iss:2 (Integration of real time quality control systems in a welding process)
Authors:
E. Nava‐Ru¨diger
M. Houlot
Ecole Nationale Supe´rieure d'Arts et Me´tiers, Laboratoire Proce´de´s et Techniques de Production Me´canique, Paris, FranceThe automation of laser welding processes requires the control of the various process components as well as the control of the laser—material interaction. These systems are essential for ensuring the quality of the weld seam as they are able to react to dynamic fluctuations during the process. During the process various phenomena occur which are potential sources of diagnostic signals: these include thermal, electrical, optical, mechanical and acoustic events. This pa...
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JLA Vol:9 Iss:3 (Experimental study of cutting thick aluminum and steel with a chemical oxygen–iodine laser using an N<sub>2</sub> or O<sub>2</sub> gas assist)
Authors:
David L. Carroll
James A. RothenflueA chemical oxygen–iodine laser (COIL) was used to cut aluminum and carbon steel. Cut depths of 20 mm in aluminum and 41 mm in carbon steel were obtained using an N2 gas assist and 5–6 kW of power on target. The same laser at the same power level produced a cut depth of 65 mm in carbon steel with an O2 gas assist; a low quality cut to a depth of nearly 100 mm in carbon steel was also demonstrated. These data are compared with existing COIL and CO2 laser cutting data. COIL cuts carbon steel and stainless steel at approximately the same rate. For a given cut depth, power and spot size...
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JLA Vol:9 Iss:3 (High power laser welding in hyperbaric gas and water environments)
Authors:
G. J. Shannon
W. McNaught
W. F. Deans
J. WatsonA hyperbaric laser welding facility has been constructed and the feasibility of high power CO2 and Nd:YAG laser welding in both high pressure gas and water environments, to simulated water depths of 500 m, has been established. From initial trials on welding through water at atmospheric pressure, it was found that the different absorption characteristics of water to 10.6 μm (CO2 laser) and 1.06 μm (Nd:YAG laser) radiation proved crucial. The Nd:YAG laser was totally unsuitable as the beam was largely diffused in the water, whereas the CO2 beam was rea...
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