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Nachrichten, Termine, Experten
A new approach to beam shaping will soon make additive manufacturing more
flexible and efficient: Fraunhofer ILT has developed a new platform that can be
used to individually optimize laser powder bed fusion (LPBF) processes.
Customized beam profiles improve component quality, reduce material losses
and enable previously impossible scaling of the build-up rate of the single beam
process. Fraunhofer ILT will be presenting the test system, which is currently
under construction, at Formnext in Frankfurt am Main from November 19 to 22.
Several studies have already impressively demonstrated that beam shaping in laser
powder bed fusion (LPBF) can improve the efficiency and productivity of this additive
manufacturing process. The Fraunhofer Institute for Laser Technology ILT and the Chair
of Technology of Optical Systems (TOS) at RWTH Aachen University are working
together to create a state-of-the-art test system enabling them to flexibly investigate
complex laser beam profiles in power classes up to 2 kW, an innovation that can be
used to customize solutions for industrial partners. This platform is designed to
integrate LPBF processes more efficiently and robustly into industrial production so that
they can meet its growing demands.
Disadvantages of the Gaussian distribution
Currently, laser powers of around 300 to 400 watts are common in many LPBF
processes. However, the standard Gaussian laser beam they use has significant
disadvantages: The high concentration of power in the beam center leads to local
overheating and undesirable material evaporation as well as process instability, both of
which can impair component quality due to spatter and pores. These issues significantly
limit the scalability of the process, meaning that the laser power available in LPBF
systems – often up to 1 kW – cannot be utilized for most materials.
"One way to speed up the process is to use several lasers and optical systems in
parallel," says Marvin Kippels, PhD student in the Laser Powder Bed Fusion Department
at Fraunhofer ILT. "However, the costs scale at least proportionally to the number of
systems installed." In addition, these systems cannot always be utilized homogeneously
in real applications, which means that productivity cannot be increased proportional to
the increase in power. A promising approach is, therefore, to increase the productivity
of the single beam process, which can also be transferred to multi-beam systems.
New possibilities through beam shaping
Previous studies have shown that even simple beam shapes with rectangular, ringshaped
or a combination of two Gaussian distributions produce promising results for
both component quality and process speed. The potential of more complex beam
shapes has so far been largely unexplored, as the necessary system technology was
lacking. This is now changing thanks to the comprehensive investigations that
researchers at Fraunhofer ILT have begun.
"The interaction of laser beam and material in the process is so complex due to its
dynamics that simulations can only provide indications of the actual melt pool
behavior," explains Kippels, who is currently setting up a new type of system that uses
LCoS-SLMs (Liquid Crystal on Silicon - Spatial Light Modulator), which will enable
researchers to investigate almost any beam profile in the LPBF process.
As it has a laser power of up to 2 kW, the innovative system is a platform for testing
new beam shapes at very high power levels in the LPBF process, which allows the
suitable system technology to be identified for an individual LPBF task. "We can
optimize the LPBF process in a targeted manner," explains Kippels. He refers specifically
to less material evaporation, less spatter formation, reduced melt pool dynamics,
smoothened melt track surface, and increased process efficiency by adapting the melt
track geometry.
Flexible beam profiles for specific requirements
Currently, system technology is often promoted as able to produce specific beam
shapes such as ring or top hat profiles. However, the choice of these beam shapes is
not based on an in-depth understanding of the underlying process mechanisms, which
is reflected in the sometimes contradictory literature on the subject. Only by
fundamental understanding the processes can research specifically define which
adjustments achieve a defined target, such as a certain melt track geometry.
This means that a beam shape must be developed and optimized for the application,
which can then ideally be implemented in the company without needing LCoS-SLM
technology. Thanks to this research platform, industrial customers and project partners
of Fraunhofer ILT can already benefit from unprecedented flexibility in researching the
laser-beam tool.
"We are still at the very beginning, but we can already see the enormous potential that
beam shaping can offer for the LPBF process," says Marvin Kippels. "There is no one
perfect beam shape; every application has its own requirements. Thanks to our flexible
beam shaping, we can find the ideal distribution for each process, the best process parameters for the task in question." To achieve this goal, several departments at the
Aachen institute support the work of Kippels and his team.
Visit us from November 19 to 22 in Frankfurt am Main at the Fraunhofer joint booth
D31 in Hall 11 and learn more about the possibilities of flexible beam shaping.
Marvin Kippels M.Sc.
Group Process & Systems Engineering
Telephone +49 241 8906-194
marvin.kippels@ilt.fraunhofer.de
Niklas Prätzsch M.Sc.
Group leader LPBF Process Technnology
Telephone +49 241 8906-8174
niklas.praetzsch@ilt.fraunhofer.de
Dr.-Ing. Tim Lantzsch
Head of Department Laser Powder Bed Fusion
Telephone +49 241 8906-193
tim.lantzsch@ilt.fraunhofer.de
Fraunhofer Institute for Laser Technology ILT
Steinbachstraße 15
52074 Aachen, Germany
www.ilt.fraunhofer.de
https://www.ilt.fraunhofer.de/en.html
https://formnext.mesago.com/frankfurt/en.html
With the system currently under construction (upper image), LCoS-SLMs can be used to generate almost ...
© Fraunhofer ILT, Aachen, Germany.
With the system currently under construction (upper image), LCoS-SLMs can be used to generate almost ...
© Fraunhofer ILT, Aachen, Germany.
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