Eike Tim Koopmann, Leonard Simon Plutz, Leonard Schmitz, Christoph Kaminsky, Henning Zeidler
In the automotive industry, the increasing number of product variants requires a high degree of flexibility, offering new applications for additive manufacturing processes. A promising and cost-effective approach is the hybrid additive manufacturing of tool components using directed energy deposition (DED). A key factor in the process is the laser power, as the temperature gradient between substrate and additive build-up has a significant influence on the formation of cracks and the contour accuracy of the component. In this paper, a laser power control system is investigated with the aim of keeping the melt pool temperature constant to reduce geometric deviations and residual stresses resulting from excessive heat input into the component. For this purpose, welding specimens are manufactured additively, followed by an optical measurement and a metallographic analysis to identify part defects. The results are used to produce a tool component with an optimized hybrid additive manufacturing strategy.
Keywords: Additive manufacturing; directed energy deposition; tool components; pyrometry, temperature control
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Development of a centrifugal laser powder bed fusion system for additive manufacturing
Koch, Jan-Hendrik, Hüsing, Florian, Janssen, Henning, Brecher, Christian
Due to the limited production rates of AM technologies, like PBF-L, the market and investment hype of AM has come to the slope of enlightenment, moving towards the plateau of productivity.
To further increase the diversity of AM machine designs and to solve limitations of conventional PBF-L the researchers of Fraunhofer IPT have rethought the kinematics of PBF-L machines. Inspired by centrifugal casting the metal powder is held on a circular track with high angular velocities causing a centrifugal acceleration of the particles in the powder bed, that overcomes gravitation. The laser optics is centered in the rotational axis melting the high velocity particles.
Process limitations are caused by the tradeoff between stabilized powder distribution and limited scanning speed. To increase processability and allow scalability the independent rotation of laser beam and powder bed were installed. This paper shows the development of a first prototype and initial process trials.
Keywords: laser powder bed fusion; rotation; centrifugal acceleration; additive manufacturing
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Scalable Additive Repair with Powder Bed Fusion using a Laser Beam
Myriam Maalaoui, Hans-Henrik Westermann, Jens Niedermeyer, Ina Meyer, Roland Lachmayer
Additive repair with powder bed fusion using a laser beam for metals (PBF-LB/M) offers a significant potential for the sustainable restoration of small metallic parts. Larger, high-value parts remain challenging for repair with PBF-LB/M, as the limited build volume of these machines constrains its applicability. This paper presents a new scalable additive manufacturing system called MESSIAH, that is designed to repair parts with up to 2500 mm in height. A repair process chain, addressing key challenges such as damage analysis, repair geometry design, and the preparation of the machine and part environment, is developed. The latter is particularly critical for ensuring precise alignment, sealing, and thermal control during processing. MESSIAH enables scalable additive repair for large components, reducing material usage, increasing process reliability, and extending the service life of large metallic components.
Keywords: additive repair; powder bed fusion by using a laser beam (PBF-LB/M); scalable
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Meisner, Dennis; Kaftiranis, Nikitas; Maiwald, Frederik; Rapp, Petra; Hierl, Stefan
Material extrusion is a widely used additive manufacturing (AM) process that is gaining industrial acceptance due to its material variety, flexibility, and relatively low invest. However, its application is limited by process-related anisotropy, caused by insufficient interlayer bonding due to insufficient temperature in the deposition area. To improve this, an adaptive laser preheating system is added to a conventional printhead. The setup includes eight separately controlled, fiber-coupled diode lasers arranged concentrically around the nozzle. This enables various intensity distributions and thus direction-dependent heating.
This work investigates the effect of three laser intensity profiles — spot, sickle, and ring — on interlayer bonding under varying cooling conditions. Laser preheating improves tensile strength in build direction up to approx. 40 %, with the ring-shaped distribution delivering the highest strength. This demonstrates the potential of laser preheating to significantly reduce anisotropy in extrusion-based AM.
However, the additional energy must be well balanced: improper thermal management can reverse the benefits of preheating and degrade mechanical properties.
Keywords material extrusion AM; fused layer modeling; laser preheating; anisotropy; interlayer bonding
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