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Thermal model and measurements of polymer laser sintering

Timothy T Diller (Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas USA)
Mengqi Yuan (Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas USA)
David L. Bourell (Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas USA)
Joseph J. Beaman (Department of Mechanical Engineering, The University of Texas at Austin, Austin, Texas USA)

Rapid Prototyping Journal

ISSN: 1355-2546

Publication date: 19 January 2015

Abstract

Purpose

The purpose of this paper is to analyze the bulk energy transport processes in the build chamber environment before and during laser sintering (LS) to provide a basis for effective and accurate thermal control for the LS process. This leads to improved mechanical properties and geometrical tolerances for LS products and may be applied to optimize operation cycle times for the LS process.

Design/methodology/approach

Computational models with two levels of complexity were built to explore the heat transfer mechanisms in the LS process. In a one-dimensional model (1D), the powder performed as a semi-infinite solid and heater flux to the powder surface was modeled with a heater control law. A two-dimensional (2D) fluid/solid finite element model of the build chamber and powder bins provided insight into the thermal processes in the build chamber.

Findings

Numerical 1D simulations were verified with measurements from sensors embedded in the build chamber powder bed. Using a 2D model, computed powder surface temperatures during the warm up and build phases were verified with an infrared camera. Convective currents in the build chamber and non-uniformities in the distribution of temperature over the radiant heater surface were found to be substantial contributors to non-uniformities in the powder bed surface temperature.

Research limitations/implications

Limited heat sources were analyzed. No three-dimensional model was built. Assumptions to decrease the part bed temperature difference were not tested.

Originality/value

These simulation and experimental results may be used to enhance thermal control and operation efficiency during the LS process and to improve LS product mechanical properties.

Keywords

Acknowledgements

This research was funded by the Department of Defense under grant number GRT00015778.

Citation

Diller, T.T., Yuan, M., Bourell, D.L. and Beaman, J.J. (2015), "Thermal model and measurements of polymer laser sintering", Rapid Prototyping Journal, Vol. 21 No. 1, pp. 2-13. https://doi.org/10.1108/RPJ-10-2012-0090

Publisher

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Emerald Group Publishing Limited

Copyright © 2015, Emerald Group Publishing Limited