Transient Model for CW and Pulsed Laser Machining of Ablating/Decomposing Materials—Approximate Analysis

Modest, Michael F.

doi:10.1115/1.2822698

Cited by 9 publications

(4 citation statements)

References 23 publications

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“…The absorptivity then increased with increasing temperature above the first phase transition temperature (melting/decomposition/vaporization) because of beam entrapment and some multiple reflections within the evolving cavity. Unlike in the past, [10][11][12]31,[56][57][58][59][60] the present work considered the transient nature of absorptivity during predictions of machined depths using the thermal model. At the slowest processing speed of 2.11 mm/s, the deepest cuts of 0.63, 0.4, 0.92, and 0.62 mm were obtained in Al 2 O 3 , Si 3 N 4 , SiC, and MgO, respectively, due to a maximum interaction of the ceramic with the laser as compared with higher processing speeds.…”

Section: Discussionmentioning

confidence: 99%

Absorptivity Transition in the 1.06 μm Wavelength Laser Machining of Structural Ceramics

Samant

Dahotre

2009

International Journal of Applied Ceramic Technology

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This study presents absorptivity transitions in two‐dimensional, low aspect ratio laser machining (cutting) of structural ceramics such as alumina (Al2O3), silicon nitride (Si3N4), silicon carbide (SiC), and magnesia (MgO) using a 1.06 μm wavelength‐pulsed Nd:YAG laser. Because temperature measurement at high temperatures is difficult, thermocouples were used to measure temperatures in the low‐temperature regime (700–1150 K). A thermal model was then iterated to obtain trends in absorptivity variation below the phase transition temperature for different ceramics. Following this, measured machined depths were used as a benchmark to predict absorptivity transitions at higher temperatures (>1150 K), using the developed thermal model. For temperatures below the phase transition, because of intraband absorption, the absorptivity decreases with an increase in temperature until the surface temperature reaches the melting point (in the case of Al2O3, Si3N4, and SiC) and the vaporization temperature (in the case of MgO). The absorptivity then continues to follow an increasing trend with increasing temperature because the physical entrapment of the laser beam in the cavity evolved during machining of the desired depth in the ceramic. Such a study would provide an efficient control over the input energy required to machine to a certain depth.

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Section: Discussionmentioning

confidence: 99%

Absorptivity Transition in the 1.06 μm Wavelength Laser Machining of Structural Ceramics

Samant

Dahotre

2009

International Journal of Applied Ceramic Technology

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“…In laser ablation, the incident beam is absorbed by film and thermal distribution on that which obeys the heat conduction equation as follows [41,42]:…”

Section: Simulation Of Thermal Distributionmentioning

confidence: 99%

Effect of scanning speed on continuous wave laser scribing of metal thin films: theory and experiment

2016

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In this paper continuous wave laser scribing of the metal thin films have been investigated theoretically and experimentally. A formulation is presented based on parameters like beam power, spot size, scanning speed and fluence thresholds. The role of speed on the transient temperature and tracks width is studied numerically. By using two frameworks of pulsed laser ablation of thin films and laser printing on paper, the relation between ablation width and scanning speed has been derived. Furthermore, various speeds of the focused 450 nm continuous laser diode with an elliptical beam spot applied to a 290 nm copper thin film coated on glass, experimentally. The beam power was 150 mW after spatial filtering. By fitting the theoretical formulation to the experimental data, the threshold fluence and energy were obtained to be 13.2 J mm −2 and 414 µJ respectively. An anticipated theoretical parameter named equilibrium border was verified experimentally. It shows that in the scribing of the 290 nm copper thin film, at a distance where the intensity reaches about 1/e of its maximum value, the absorbed fluence on the surface is equal to zero. Therefore the application of continuous laser in metal thin film ablation has different mechanism from pulsed laser drilling and beam scanning in printers.

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“…[1][2][3][4][5][6][7] As a result of melting and evaporation, a plume of hot, ionized material vapor mixed with ambient gas forms above the surface. An example of a process where plume formation is important is CO 2 laser welding.…”

Section: Introductionmentioning

confidence: 99%

Plume Formation During Laser Heating of a Solid Surface

Kim¹,

Kim²,

Kang³

et al. 2008

Jnl of Comp & Theo Nano

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A mathematical model of the dynamics of laser-produced heating, evaporation and plume formation is presented. The condensed material model includes conduction heat transfer as well as melting and evaporation phase changes. The localized heating and evaporation caused by focused laser radiation forms a plume of mixed vapor above the material surface. The beam is absorbed and refracted as it traverses the plume, thus modifying its power density on the surface. In this work, variations of heat transfer rate during laser heating and effects of a plume formed by vapor from an iron surface are studied using an axisymmetric mass, momentum and energy transport model. The simulation results quantify the heat transfer rate in the plasma plume, heat losses due to radiation, and variations of heat input into the material.

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Transient Model for CW and Pulsed Laser Machining of Ablating/Decomposing Materials—Approximate Analysis

Cited by 9 publications

References 23 publications

Absorptivity Transition in the 1.06 μm Wavelength Laser Machining of Structural Ceramics

Absorptivity Transition in the 1.06 μm Wavelength Laser Machining of Structural Ceramics

Effect of scanning speed on continuous wave laser scribing of metal thin films: theory and experiment

Plume Formation During Laser Heating of a Solid Surface

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