Fraunhofer ILT: Beam shaping platform optimizes LPBF processes

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 on a state-of-the-art test system that enables the flexible investigation of complex laser beam profiles in power classes up to 2 kW - this innovation enables customized solutions for industrial partners. The aim of this platform is to integrate LPBF processes more efficiently and robustly into industrial production so that they can meet the growing demands of the industry. Currently, many LPBF processes use laser powers of around 300 to 400 watts. However, the standard Gaussian laser beam 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, which can impair component quality due to spatter and pores. This significantly limits 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 only a disproportionately low increase in productivity is achieved. 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 shaping with rectangular, ring-shaped or the combination of two Gaussian distributions produce promising results in terms of 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 the Fraunhofer ILT have begun. "The laser beam/material interaction 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) to enable the investigation of almost any beam profile in the LPBF process. With a laser power of up to 2 kW, the innovative system offers a platform for testing new beam shapes at very high powers in the LPBF process. This 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, referring specifically to: less material evaporation, less spatter formation, reduction of melt pool dynamics, smoothing of the melt track surface, increase in process efficiency by adapting the melt track geometry.

Flexible blasting profiles for specific requirements

Currently, system technology is often advertised as being 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 a fundamental understanding of the processes makes it possible to specifically define which adjustments achieve a defined target, such as a certain melt track geometry. This requires the development of a beam shape optimized for the application, which can then ideally be implemented in the company without the use of LCoS-SLM technology. With this research platform, industrial customers and project partners of the Fraunhofer ILT can already benefit from unprecedented flexibility in researching the blasting tool. "We are still at the very beginning, but we can already see the enormous potential that beam shaping offers 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. Visitors to the Formnext trade fair (November 19 to 22, 2025) in Frankfurt am Main can find out more about the possibilities of flexible beam shaping at the Fraunhofer joint stand D31 in hall 11.