LASER WoP Talk No. 3 on March 9, 2022

Photons in Production—From Science to Industrial Application

At the special show “Photons in Production”, current research in the field of laser materials processing will be presented at the exhibition booth by the following cooperation partners:

• Bavarian Laser Center (blz) and the
• Institute for Machine Tools and Industrial Management (iwb) of the Technical University of Munich (TUM)
• Institute of Photonic Technologies (LPT) at Friedrich-Alexander-Universität Erlangen-Nürnberg

You can get a first insight into the topics through the webinar series “Photons in Production—From Science to Industrial Application” in advance. Topics include simulation and control of laser-based additive manufacturing, material processing using ultra short pulse lasers, and laser applications for electromobility.

SPEAKERS & TOPICS

Florian Kaufmann & Richard Rothfelder: Beam shaping in laser material processing and Additive Manufacturing

Conventional laser material processing regardless of whether it is welding, cutting or Additive Manufacturing, uses Gaussian beam profiles to achieve required results. This means the intensity profile in the focal plane can be described by a Gaussian function. This intensity distribution does not have to represent the optimum for the given process. By shaping the beam and therefore adapting the intensity it is possible to create a beneficial distribution for a specific application. The changed boundary conditions allow enhanced process control and stability. In this talk exemplary possible benefits for material processing and Additive Manufacturing will be discussed.

Oliver Hentschel: Two Color Pyrometer for temperature and melt pool size control in AM process

In this study, the potential of high-speed (HS) ratio pyrometers as tool for process control in Additive Manufacturing (AM) has comprehensively investigated and demonstrated with DED-LB\M. For this, the high-speed ratio pyrometer H322 from the company Sensortherm has coaxially implemented into the beam path of the laser processing head YC52 provided by Precitec. The on-axis alignment of the ratio pyrometer enables a feed direction-independent measurement of the ratio temperature within the interaction zone. The pyrometer is equipped with a typical PID—controller required for closed loop control. In closed-loop operation, the ratio temperature (controlled variable) of the process zone is continuously measured. As soon as the measuring value falls below or exceeds a target value defined in advance, the laser beam power is adapted accordingly (manipulated variable) in order to ensure constant ratio temperature and associated with this constant thermodynamic boundary conditions during the manufacturing of multi-layered specimens.

We could prove that in closed looped operation an approx. constant process zone temperature and associated with this a stable thermodynamic AM process can be achieved. The laser power control allows the generation of 3D-specimen (e.g. thin walls or cube-like solids) with outstanding dimensional accuracy. In addition to this, the control of the ratio temperature leads to a strict homogeneous microstructure and constant hardness.

Frederik Buckstegge is a research associate at Fraunhofer ILT/RWTH TOS.

High Precision laser processing is a growing part in various industrial sectors such as semiconductor- and electronics manufacturing and medical component manufacturing. In order to ensure highest precision in laser processes such as cutting and micro/nanostructuring, the process in question has to be either studied in detail to yield optimal process parameters, or there has to be a method of measuring relevant parameters of quality during the process to directly control the process while it is running. Optical Coherence Tomography (OCT) has the potential to be a tool for in-line post-process measurements of relevant parameters such as ablation depth and geometry, as well as real-time measurements during the process itself. The presentation will provide a short description of the OCT principles and first experiments combining ultrashort pulse laser surface ablation with in-line OCT measurements.

Lazar Tomcic: Laser Material Processing as an Enabler for Innovations in Electromobility

Electric vehicles can significantly reduce the CO2 emissions of the mobility sector and, therefore, it is essential to make electromobility technically and economically attractive for producers and customers. Laser material processing can reduce production costs and enable new designs of energy storages. In this presentation, relevant laser processes will be discussed, which are currently being researched and can lead to significant advantages in various applications for electromobility.

Daniel Wolf: Simulation-based prediction of stress-induced cracking during powder bed-based melting of metals by laser irradiation (PBF-LB/M).

During powder bed melting of metals with a laser beam (PBF-LB/M), high residual stresses occur due to local temperature differences. These residual stresses can lead to cracks during the manufacturing process. In this presentation, an approach for the simulative prediction of stress induced cracks in IN718 is presented.

Moderator: Andreas Wimmer

Andreas Wimmer was born 1989 in Altoetting and studied Physics in Berlin (Free University of Berlin) and Munich (Ludwig Maximilian University of Munich). Since 2018, he has been a Research Associate at the Institute for Machine Tools and Industrial Management at Technical University of Munich (TUM) in the department Additive Manufacturing and became head of this department in 2021. His research focusses on the in-situ alloying during the Powder Bed Fusion of Metals using a Laser Beam.