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Approaches to minimize overhang angles of SLM parts

Michael Cloots (Irpd AG, St.Gallen, Switzerland)
Livia Zumofen (Center for Product and Process Development, ZHAW, Winterthur, Switzerland)
Adriaan Bernardus Spierings (Institute for Rapid Product Development, inspire AG, St. Gallen, Switzerland)
Andreas Kirchheim (Center for Product and Process Development, ZHAW, Winterthur, Switzerland)
Konrad Wegener (Institute for machine tools and manufacturing IWF, ETH Zürich, Zurich, Switzerland)

Rapid Prototyping Journal

ISSN: 1355-2546

Article publication date: 20 March 2017

962

Abstract

Purpose

For geometries exhibiting overhanging surfaces, support structures are needed to dissipate process heat and to minimize geometrical distortions attributed to internal stresses. The use of support structures is often time- and cost-consuming. For this reason, this study aims to propose an approach which minimizes the use of such structures.

Design/methodology/approach

For minimizing the use of support structures, process parameters in combination with a contour-like exposure strategy are developed to realize support-less overhanging structures of less than 35°. These parameters are implemented in a shell-core strategy, which follows the idea of applying different processing strategies to the critical (overhanging) shell and the uncritical core of the part. Thereby, the core is processed with standard parameters, aiming a dense material. On the critical shell, optimized processing parameters are applied, reaching good results in terms of surface quality, especially at extreme overhang situations.

Findings

The results show that the selective laser melting (SLM) technology is able to realize support-less overhanging surfaces by choosing suitable scan strategies and process parameters. Particularly good results are always obtained when the exposure direction of the shell is parallel to the contour of the sample.

Originality/value

The validity of the results is demonstrated through the successful reproduction of the build strategy on two commercial SLM machines, reaching support-free builds of surfaces with an angle to the horizontal of less than or equal to 30°.

Keywords

Acknowledgements

The authors would like to thank their colleague Alex Frauchiger who supported them with his profound knowledge in SLM.

Citation

Cloots, M., Zumofen, L., Spierings, A.B., Kirchheim, A. and Wegener, K. (2017), "Approaches to minimize overhang angles of SLM parts", Rapid Prototyping Journal, Vol. 23 No. 2, pp. 362-369. https://doi.org/10.1108/RPJ-05-2015-0061

Publisher

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Emerald Publishing Limited

Copyright © 2017, Emerald Publishing Limited

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