Effects of intrapulse structure on hole geometry in laser drilling

    Authors

    J. Cheng; F. J. Kahlen;A. Kar

    Comments

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    Abbreviated Journal Title

    J. Laser Appl.

    Keywords

    laser drilling; taper angle; recast layer; laser pulse shape; pulse; length; Materials Science, Multidisciplinary; Optics; Physics, Applied

    Abstract

    Lasers have been established as a commercial tool for drilling holes in a variety of materials. The beam quality and temporal shape of the laser pulse have been identified as critical parameters to create high quality (deeper holes, minimum taper angle, and minimum recast layer) holes. However, little attention has been directed toward an analytic investigation of the effect of different temporal pulse shapes on these product variables. In this study, a leading-edge, sharp-spiked, and a rectangular Nd:YAG laser pulse were used to drill holes in stainless steel 304 to examine the effects of these temporally different laser pulses on the drilling process. It is found that holes drilled with the sharp-spiked laser pulse are significantly deeper than for the case of rectangular pulses. Also an optimum processing regime is identified to drill holes with minimum taper angle and recast layer. A mathematical model describing the drilling process is presented in this article for different temporal profiles of the pulsed laser beams. The model assumes one-dimensional heat conduction in the material and it incorporates the Stefan conditions at the solid-liquid and liquid-vapor interfaces. The predicted drill depth and recast layer thickness are larger than the experimental data but follow the same trend. (C) 2000 Laser Institute of American. [S1042-346X(00)00106-6].

    Journal Title

    Journal of Laser Applications

    Volume

    12

    Issue/Number

    6

    Publication Date

    1-1-2000

    Document Type

    Article

    Language

    English

    First Page

    232

    Last Page

    238

    WOS Identifier

    WOS:000165766000002

    ISSN

    1042-346X

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