Overview and details of the sessions of this conference. Please select a date or location to show only sessions at that day or location. Please select a single session for detailed view (with abstracts and downloads if available).
Please note that all times are shown in the time zone of the conference. The current conference time is: 25th Oct 2021, 01:49:08pm CEST
Session Chair: Prof. Michael F. Zaeh, Technical University of Munich, Germany
Location:Room 2 ICM
2:45pm - 3:00pm
Fabrication strategies with fixed diffractive optical elements for high speed two-photon polymerization
Francisco Gontad, Sara M. Vidal, Nerea Otero-Ramudo, Pablo Romero-Romero
AIMEN Technology Centre, O Porriño, ES36418, Pontevedra, Spain
The benefits of Two-Photon Polymerization (TPP) are well known for the fabrication of 3D structures with micron and even submicron sizes. However, the fabrication time of these structures is still far from being competitive with other techniques. In this work, the use of fixed Diffractive Optical Elements (DOEs) is presented as a valid approach to boost the fabrication speed of TPP. In this way, the fabrication strategy for different 2.5D and 3D microstructures, taking advantage of the use of DOEs with different optical configurations, is presented and discussed. The results of this study suggest that the fabrication speed can be increased up to 20 times through the correct combination of DOE and path planning, without the need of an excessive average power.
3:00pm - 3:15pm
Process strategies on laser-based melting of glass powder
Thomas Schmidt1, Susanne Kasch1, Fabian Eichler2, Laura Katharina Thurn2
This paper presents the laser-based powder bed fusion (L-PBF) using various glass powders (borosilicate, quartz glass). Compared to metals, these require adapted process strategies. First, the glass powders were characterized by means of various methods with regard to their material properties and their processability in the powder bed. This was followed by investigations of the melting behavior of the glass powders with different laser wavelengths (10.6µm, 1070nm). In particular, the experimental setup of a CO2 laser was adapted for the processing of glass powder. An experimental setup with integrated coaxial temperature measurement/control and an inductively heatable build platform was created. This allowed the L-PBF process to be carried out at the transformation temperature of the glasses. Furthermore, the component’s material quality was analyzed on three-dimensional test specimen with regard to porosity, roughness, density and component accuracy in order to evaluate the developed L-PBF parameters and to open up possible applications.
3:15pm - 3:30pm
Comparison of different density measurement techniques for laser assisted powder bed fusion
Lisa Schade1, Gabor Matthäus1, Hagen Kohl1, Burak Yürekli1, Tobias Ullsperger1, Brian Seyfarth1, Stefan Nolte1,2
1Friedrich-Schiller-Universität Jena, Germany; 2Fraunhofer Institute for Applied Optics and Precision Engineering, IOF Jena, Germany
One of the major quality control criteria for additively manufactured parts is the density achieved. Besides fundamental properties like microstructure, residual strain or impurities, the density fundamentally defines how the final product matches the intended material properties. In general, mostly surface inspections of randomly prepared cross sections are undertaken. On the one hand side, this approach delivers important information regarding the morphology and distribution of pores, however, on the other hand side, this characterization only considers a small fraction of the entire sample volume and therefore cannot reflect the true density without a significant level of uncertainty. In this work, we investigate three different measurement techniques, light microscopy, x-ray tomography and pycnometry with a focus on their advantages and disadvantages. The results show significant differences of the obtained density values with deviations in the range of several percent depending on the underlying material.
3:30pm - 3:45pm
Developing process parameters through CFD simulations
Pareekshith Allu1, Frieder Semler2
1Flow Science Inc., United States of America; 2Flow Science Deutschland GmbH, Germany
Laser-material interaction is complex, and to accurately simulate it requires implementing the physics models that are relevant at these temporal and spatial scales. Process parameters such as laser power, scanning velocity, geometric scanning path, pre-heating temperature and powder size distribution influence the melt pool dynamics, which controls the stability of the additive manufacturing process. In this presentation, we will look at underlying mechanisms behind the formation of defects such as balling, porosity and spatter using computational thermal-fluid dynamics models built in FLOW-3D AM. While low energy densities can lead to lack of fusion defects, high energy densities result in strong recoil pressure and unstable keyholes that can lead to the formation of porosity and spatter. In addition to helping with process parameter development for both LPBF and DED processes, such models also output thermal gradient and cooling rate data that can be used to predict microstructure evolution.
3:45pm - 4:00pm
Laser-induced forward transfer (LIFT) of micro-LED devices
Alberto Piqué, Ray Auyeung, Kristin Charipar, Heungsoo Kim, Michael Malito, Nicholas Charipar
U.S. Naval Research Laboratory, United States of America
We explore the application of laser-induced forward transfer (LIFT) techniques for laser printing of micro-LED devices. LIFT enables printing of functional materials ranging from silver nano-inks to working devices such as bare-die semiconductor components over a wide range of surfaces in an additive fashion achieving high transfer throughputs. LIFT is a non-mechanical, non-contact device transfer process operating beyond the size limits of pick-and-place methods. That is, LIFT offers a ‘lase-and-place’ approach for transferring the building blocks required for the fabrication of a wide range of functional circuits. LIFT techniques are being investigated by the U.S. Naval Research Laboratory to print micro-LED devices for applications in hybrid electronics. Examples of structures and circuits made by LIFT and their role in the development of next generation laser micro processing techniques will be presented.
This work was funded by the Office of Naval Research (ONR) through the Naval Research Laboratory Basic Research Program.