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Research Papers

Optimization of Scan Strategies in Selective Laser Melting of Aluminum Parts With Downfacing Areas

[+] Author and Article Information
Raya Mertens

Division of Production Engineering,
Machine Design and Automation,
Department of Mechanical Engineering,
University of Leuven (KU Leuven),
Leuven 3001, Belgium
e-mail: raya.mertens@kuleuven.be

Stijn Clijsters

Division of Production Engineering,
Machine Design and Automation,
Department of Mechanical Engineering,
University of Leuven (KU Leuven),
Leuven 3001, Belgium
e-mail: stijn.clijsters@kuleuven.be

Karolien Kempen

Division of Production Engineering,
Machine Design and Automation,
Department of Mechanical Engineering,
University of Leuven (KU Leuven),
Leuven 3001, Belgium
e-mail: karolien.kempen@kuleuven.be

Jean-Pierre Kruth

Division of Production Engineering,
Machine Design and Automation,
Department of Mechanical Engineering,
University of Leuven (KU Leuven),
Leuven 3001, Belgium
e-mail: jean-pierre.kruth@kuleuven.be

1Corresponding author.

Contributed by the Manufacturing Engineering Division of ASME for publication in the JOURNAL OF MANUFACTURING SCIENCE AND ENGINEERING. Manuscript received April 15, 2014; final manuscript received September 9, 2014; published online October 24, 2014. Assoc. Editor: Darrell Wallace.

J. Manuf. Sci. Eng 136(6), 061012 (Oct 24, 2014) (7 pages) Paper No: MANU-14-1191; doi: 10.1115/1.4028620 History: Received April 15, 2014; Revised September 09, 2014

Selective laser melting (SLM) is an additive manufacturing technique in which metal products are manufactured in a layer-by-layer manner. One of the main advantages of SLM is the large geometrical design freedom. Because of the layered build, parts with inner cavities can be produced. However, complex structures, such as downfacing areas, influence the process behavior significantly. The downfacing areas can be either horizontal or inclined structures. The first part of this work describes the process parameter optimization for noncomplex, upfacing structures to obtain relative densities above 99%. In the second part of this research, parameters are optimized for downfacing areas, both horizontal and inclined. The experimental results are compared to simulations of a thermal model, which calculates the melt pool dimensions based on the material properties (such as thermal conductivity) and process parameters (such as laser power and scan speed). The simulations show a great similarity between the thermal model and the actual process.

Copyright © 2014 by ASME
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References

Figures

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Fig. 1

Schematic overview of the SLM process

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Fig. 2

Dross formation due to deep unstable melt pool in downfacing areas with a length of 10 mm

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Fig. 3

Downfacing structures. (a) Horizontal and (b) Inclined.

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Fig. 4

Relative density in function of scan speed and laser power

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Fig. 5

Microscope images show high density of 99.3%. (a) Top view and (b) Side view.

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Fig. 6

Different zones of a downfacing structure

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Fig. 7

Simulation results. (a) Normal scanning situation on solidified material and (b) Downfacing scanning situation.

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Fig. 8

Comparison of the different powers used in zone 1. The lines indicate the borders of a perfect downfacing area. The length of the pieces is 10 mm. (a) 40 W, (b) 50 W, (c) 60 W, (d) 70 W, (e) 80 W, and (f) 90 W.

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Fig. 9

Comparison of two downfacing areas of 14 mm × 14 mm. When using high powers, large lumps are formed. (a) 35 W and (b) 85 W.

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Fig. 10

Picture of a downfacing structure with a length of 10 mm

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Fig. 11

Warp of the downfacing structure

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Fig. 12

Heat transport situation in downfacing structures

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Fig. 13

Wide downfacing structure of 40 mm

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Fig. 14

Adapted geometry to obtain longer downfacing structures with a length of 20 mm. (a) Geometry and (b) Result.

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Fig. 15

Different zones of an inclined area with angle α

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Fig. 16

Microscope images of inclined structures (α = 60 deg) with different power used in zone 1. (a) 100 W, (b) 200 W, and (c) 300 W.

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Fig. 17

Microscope images of inclined structures (α = 45 deg) with different power used in zone 1. (a) 100 W, (b) 200 W, and (c) 300 W.

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Fig. 18

Microscope image of the inclined structure of 30 deg

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Fig. 19

Parts produced with inclined structures. (a) 60 deg, (b) 45 deg, and (c) 30 deg.

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