A1 Journal article (refereed), original research

Effect of process parameters on the formation of single track in pulsed laser powder bed fusion


Open Access publication

Publication Details
Authors: Laitinen Ville, Piili Heidi, Nyamekye Patricia, Ullakko Kari, Salminen Antti
Publisher: Elsevier: Creative Commons Attribution Non-Commercial No-Derivatives License
Publication year: 2019
Language: English
Related Journal or Series Information: Procedia Manufacturing
Volume number: 36
Start page: 176
End page: 183
Number of pages: 8
ISSN: 2351-9789
JUFO-Level of this publication: 1
Open Access: Open Access publication

Abstract

There has been increasing interest in Laser Powder Bed Fusion (L-PBF) of
metallic materials as a promising manufacturing technology. Although
most L-PBF systems utilize laser beams with continuous wave emission
(L-PBF(CW)), the possibility of using pulsed lasers (L-PBF(P)) has
become available in some industrial L-PBF machines over the past few
years. Previous studies suggest that the use of pulsed lasers could
enable larger control of heat input and melt pool formation during the
process, and could thus enable improvement of spatial resolution and
feature sizes in L-PBF. In this study, the experiments were implemented
using a pulsed laser in combination with continuous scanning movement
instead of the ‘point-and-shoot’ method typically used by industrial
L-PBF(P) machines of today. The experiments were executed using a trial
L-PBF system (IPG ytterbium fiber laser, wavelength 1075 nm) for
gas-atomized stainless steel 316L powder on compositionally similar
substrates. Single tracks were melted with three different pulse lengths
(50, 100, and 200 µs) by using a constant layer thickness of 50 µm,
while varying pulse repetition rate, scanning speed and laser power
based on six preset values of volume energy density (VED) of 36-120 J/mm3.
In order to allow a comparison to be made, additional samples were
manufactured by using the CW emission of the same laser. It was observed
that the L-PBF(P) samples yielded narrower tracks in comparison to the
samples manufactured using CW emission. In addition, the results of the
experiments show that, while maintaining constant VED values,
decreasing the pulse length or scanning speed decreased the widths of
the tracks and their penetration into the substrate. Consequently, it
was noticed that shorter pulse lengths require more overlap between
consecutive pulses in order to produce continuous tracks. Pulsed
emission shows potential for improving the spatial resolution of the
L-PBF process.


Last updated on 2020-20-03 at 10:03