June 21 - 24, 2021
International Congress Center, Munich, Germany
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: 29th Jan 2022, 04:32:58am CET
Program for LiM 2021|
|Location: Room 5|
|Date: Tuesday, 22/June/2021|
|10:00am - 11:00am||Machine Learning for Laser Processing|
Location: Room 5
Session Chair: Anne Feuer, University of Stuttgart, Germany
10:00am - 10:30am
Invited Talk: Applications of artificial intelligence and machine learning in laser materials processing
Laboratory for Advanced Materials Processing, EMPA, Switzerland
Laser materials processing (welding / additive manufacturing) are known to be highly dynamic. The reason is the non-linear nature of light-matter interactions. This not only complicates the reproducibility of the process quality in mass production but it is also a challenge for in situ and real-time quality monitoring and control.
Under such circumstances, our approach has been to record signals from different sensors such as acoustic emission and optical sensors. However, due to the complex character of the signals, traditional signal processing methods are limited to extract the useful information about the process quality. To overcome this difficulty, we use state-of-the-art artificial intelligence and machine learning methods as they allow building complex empirical models from complex structured datasets.
The presentation makes an overview of our approach and results for laser processes.
10:30am - 10:45am
Determination of the beam position in laser deep penetration welding using coaxially acquired images of the keyhole front and machine learning
1Institute of Photonic Technologies (LPT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Konrad-Zuse-Straße 3/5, 91052 Erlangen, Germany; 2Erlangen Graduate School in Advanced Optical Technologies (SAOT), Friedrich-Alexander-Universität Erlangen-Nürnberg, Paul-Gordan-Straße 6, 91052 Erlangen, Germany
The joining technology of laser beam welding offers high flexibility and productivity. However, the small laser beam focus demands dependable quality assurance to ensure a sufficient connection of the parts. In keyhole welding of metal sheets in butt joint configuration, a gap is visible at the keyhole front, which correlates with the leading joint position. This process feature can be used for quality control by arranging a high-speed camera coaxially to the laser beam to monitor the keyhole. Here, we present a machine learning approach for a robust determination of the beam position relative to the joint based on the keyhole front morphology. For this purpose, we conducted a series of experiments to produce a set of labeled images, which are used to train a convolutional neural network. After training on the data the network can predict the keyhole front gap position, setting the foundation for a quality control system.
10:45am - 11:00am
Use of hyperspectral imaging (HSI) in combination with machine learning methods for the critical powder parameters and corresponding part properties. prediction of
1Siemens AG, Germany; 2Fraunhofer IWS; 3TU Dresden
Additive manufacturing processes are generally operated in an industrial environment with defined parameters for specific materials and specific applications. The machines used can only be individually controlled to a limited extent. This means that the material properties are directly related to the component qualities. The evaluation of materials before and during the construction process is thus an essential component in the quality management of the AM production chain and the basis for optimized use and reuse of production value materials.
The analysis of metal powders by HSI represents a potential novel method for the qualification of powders.
To this end, the use of hyperspectral imaging, in combination with machine learning methods, for the prediction of critical powder parameters such as the rheology, the morphology and the chemical properties of the powders will be demonstrated. Furthermore, it is discussed if a prediction of the component properties by HSI sensing.
|11:15am - 12:30pm||Macro: Laser Processing for Electrical Components|
Location: Room 5
Session Chair: Jakob R. Ermer, Bayerisches Laserzentrum GmbH (blz), Germany
11:15am - 11:30am
Laser in vacuum spot welding of electrical steel sheets with 3.7% Si-content
Welding and Joining Institute, RWTH - Aachen University, Germany
The energy efficiency of electric motors is largely determined by the magnetic and electrical properties of the soft magnetic core material. For high-frequency applications in the automotive sector, the cores usually consist of iron-silicon alloys with several lamellae electrically insulated from each other to minimize eddy current loss. To join these lamellae, a novel method with individual, statistically distributed weld spots instead of continuous linear welds is used. The influence of beam power and beam intensity on the weld geometry, grain structure and torsional strength of the material is investigated.
11:30am - 11:45am
Solutions of laser material processing for electric mobility – evaluation of the Technology Readiness Level
Technical University of Munich, Institute for Machine Tools and Industrial Management, Germany
Battery technology and lightweight design are central fields of research and development when it comes to making electric mobility technically and economically attractive for producers and customers. In this context, laser material processing will be a driver to enable innovations in future product generations. For this reason, the publication addresses the most relevant laser-based production technologies that are currently being researched or about to be transferred to applications in electric mobility. In order to give a structured and uniform overview, the advantages of individual processes are mentioned and the technology-specific state of the art is quantitatively presented based on a methodical procedure for the evaluation of the Technology Readiness Levels. Upon this, the challenges for the deployment in industrial production are specified, which is the basis to describe the need for adaption and further development in laser material processing
11:45am - 12:00pm
System and process development for functionalization of electrical components by laser-based gold micro deposition
1Fraunhofer Institute for Production Technology IPT, Germany; 2Laboratory for Machine Tools and Production Engineering (WZL) of RWTH Aachen University
During the manufacture of electrical contact components, the contacts are coated with precious metals. Currently, energy- and resource-intensive electroplated coatings are used. A sustainable alternative is the local functionalization of sheet parts using small gold spots with the appropriate system technology for laser-based micro wire deposition. However, the necessary process reliability and required short cycle times represent a challenge for the technology. Within this paper, the system development of a stand-alone coating system is described. The approach presented is based on a laser beam deflection unit, fully automatic laser system control, a 5-axis wire head and a quality assurance system. An analysis of the deposition results was carried out, taking into account crucial process parameters. The resource efficiency study shows significantly reduced gold usage through local sustainable coating. Almost 100% material utilization is achieved, while gold spots geometry and position can be adjusted and replace the full surface electroplating coating.
12:00pm - 12:15pm
Laser technologies for battery pack production
The global mobility revolution is in full swing. The demand for components for electric cars and alternative drives is rising continuously. Many production approaches are making use of the benefits of laser technologies. It connects battery cells to form modules or packs. It ensures tightness and crash safety when joining battery packs and trays.
This paper offers an insight into the requirements of battery packs as well as the innovative joining technology solutions for the material specifics, which are made possible by the use of novel laser and system developments in industrial practice. Furthermore, the trends of future battery packs will be presented. Finally, a spotlight will present the next generation of laser and joining technologies for use in battery system manufacturing and place them in the context of existing material-specific challenges, such as helium-tight welding of aluminum alloys.
12:15pm - 12:30pm
Contacting of cylindrical lithium-ion batteries using short pulse laser
Technical University of Munich, Institute for Machine Tools and Industrial Management, Garching, Germany
The increasing demand for electric vehicles requires innovative manufacturing processes to improve the electrical performance and decrease the production costs of energy storages. Laser beam welding (LBW) is a highly flexible and fast process for connecting multiple battery cells automatically. Highly electrical conductive materials such as copper and aluminum are challenging in terms of LBW. A possibility to overcome these challenges, such as the high reflectivity and thermal conductivity, is the use of nanosecond laser pulses with peak powers up to several kilowatts. In experiments, this process was found to achieve narrow welds with high aspect ratio and low heat input. Beam oscillation was investigated in order to widen the weld seams and enhance the electrical conductivity and mechanical strength. This study shows the proof of concept and parameter investigation for the use of short pulse LBW for difficult to weld lap joints containing copper and aluminum or hilumin.
|Date: Wednesday, 23/June/2021|
|10:00am - 11:00am||Additive Manufacturing: Powderbed, Ti-6Al-4V|
Location: Room 5
Session Chair: Richard Rothfelder, Institute of Photonic Technologies (LPT), Germany
10:00am - 10:15am
Effect of microstructure for additively manufactured Ti64 plate on modulated pulses by vacuum SLM.
1Graduate School of Engineering, Osaka University, 1-1 Yamadaoka, Suita, Osaka, 565-0871, Japan; 2Graduate School of Science and Engineering, Kindai University, 3-4-1 Kowakae, Higasiosaka, Osaka, 577-8502, Japan; 3Joining and Welding Research Institute, Osaka University, 11-1 Mihogaoka, Ibaraki, Osaka, 567-0047, Japan
Selective laser melting (SLM), which is an additive manufacturing technology, is a method that metal powder was melted and solidified by laser. There was a problem that distribution of crystal grain size was caused inhomogeneous by excessive input because of laser irradiation layer by layer. It was thought that anisotropy could be eliminated by controlling grain growth through precise control of heat input. In order to control a heat input, modulated pulses for laser were used. Purpose in this study, Ti64, which is clinical applied as an implant material due to its biocompatibility as well as its high corrosion and mechanical resistance, was fabricated with modulation pulses of laser. As the results, it was found that the pulse energy increase with increase the grain size of Ti64 plate fabrication.
10:15am - 10:30am
Development of a machine concept for the processing of Ti6Al4V in the LPBF process under silandized argon atmosphere
Laser Zenrum Hannover e.V., Germany
The presence of oxygen in the LPBF process leads to embrittlement in the workpiece in materials with high affinity to oxygen. Especially the metal powder Ti6Al4V requires a special protective atmosphere during processing. By doping the argon 1.5% with monosilane, the residual oxygen of a usual argon atmosphere is bound and reduced to a value typical for XHV (Extreme High Vacuum).
Basically, the development of an LPBF system according to VDI 2221 is presented. The admixture of silane requires an innovative machine concept in order to ensure the compatibility of the materials used and to prevent the process gases from becoming hazardous. The phases of development are accompanied by comprehensive reaction studies and flow simulations. The resulting concept relies on a compact machining area (Ø100x100mm) and breaks new ground in the processing of special materials, not only through the process gases used, but also in powder and workpiece management.
10:30am - 10:45am
Influence of laser focus shift on porosity and surface quality of additively manufactured Ti-6Al-4V
Laser Zentrum Hannover e.V., Germany
In laser-based powder bed fusion of metals (PBF-LB/M) an increase of the laser spot size by shifting the focus position offers the opportunity of reducing the overall scanning time as well as achieving a more stable melt pool behavior. However, the influence on porosity and surface roughness of bulk samples has received little attention so far. In this work, the influence of laser focus shift (Yb-fiberlaser, minimum beam diameter of 35 µm) on part porosity as well as top and side surface roughness is investigated for additively manufactured Ti-6Al-4V. The focusing lens position relative to its standard setting is varied between 1.2 mm and -8.7 mm and the resulting track width is evaluated. Further, the main processing parameters are varied. The influences and interaction effects of all varied parameters are statistically evaluated according to the design of experiments approach. Optimum settings for low porosity and surface roughness are presented.
|11:15am - 12:30pm||Process Innovations|
Location: Room 5
Session Chair: Prof. Jean Pierre Bergmann, Technische Universität Ilmenau, Germany
11:15am - 11:30am
Study of pointing stabilization unit for femtosecond fiber beam delivery system
Recent development of hollow-core inhibited coupling fibres paves the way to fibre beam delivery for femtosecond laser manufacturing applications. Nevertheless, reaching sufficient quality and reliability for such a functionality in industrial environment requires a Laser-fiber coupling system immunes to thermal and vibration fluctuations. As the Microstructure hollow-core fiber damage threshold is dependent of beam pointing stability of the laser system, beam stabilization sub-system has to be implemented to insure stable operation. This study attempts to qualify two beam stabilisation systems. The first one is two piezo motors coupled with Four quadrant detectors. The second one is Cailabs’ all-optical mode-cleaner system based Multi-Plane Light Conversion (MPLC) technology. MPLC enables a high control of modes propagation: a misaligned beam is projected on an adapted mode basis and the unwanted energy is then dumped. To do such output fibre transmission efficiency and beam quality are investigated under controlled fluctuation of beam pointing.
11:30am - 11:45am
Superimposed beam deflection using acousto-optical deflectors in combination with a galvanometer scanner
1Applied Laser and Photonics Group, University of Applied Sciences Aschaffenburg, 63739 Aschaffenburg,Germany; 2Applied Laser Technologies, Ruhr-University Bochum, 44801 Bochum, Germany
We report on the deflection behavior of a combined scanning system consisting of two acousto-optical deflectors (AOD) and a galvanometer scanner for ultra-short laser pulses. Firstly, the dynamic behavior and the precision of the individual AOD subsystem are characterized within it’s deflection range at different positioning frequencies. For the combined scanning system the roundness of the focus spot within an AOD scan field and the scan field dimensions at different galvanometer deflections are analyzed. In addition, the roundness of the spot and the scan field dimensions are determined as a function of galvanometer deflection and focus level. The investigations show that focus spot roundness’s > 90 % in a z-range of 200 µm can be realized in a galvanometer scanning field of 30 x 30 mm with positioning frequencies of up to 1 MHz using the superimposed laser beam deflection, highlighting it´s great potential for highly dynamic laser micromachining.
11:45am - 12:00pm
Advanced quasi-simultaneous welding – a new approach to laser welding of polymers
Evosys Laser GmbH, Germany
Evosys Laser GmbH is developing a new variant of laser plastic welding, the so called Advanced Quasi-Simultaneous Welding (AQW). It combines two monochromatic laser beam sources and wavelengths in a sequential time pattern. By using two different wavelengths in a quasi-simultaneous welding process, the specific deposition of radiation energy and heat into each joining partner can be better controlled. This results into a more reliable welding operation with an enlarged process window.
Trials employing the new AQW process show that a significant improvement in weld seam quality is possible compared to the standard process with only one laser source. Due to the wavelength of the secondary laser source, more energy is deposited in the transmissive joining partner. The increased volume of plasticized material in this part is leading to an increased weld strength. Furthermore, it facilitates processing high-performance thermoplastics which often impose challenges to the laser welding process.
12:00pm - 12:15pm
Fully reflective annular laser beam shaping for laser beam welding at 16kW
1Cailabs, France; 2Institut Maupertuis, France
Laser Beam Welding (LBW) is commonly used in many fields of the industry, ranging from automotive and naval to aerospace. In order to improve LBW performance (process speed and quality as well as thickness of the parts to be weld) handling higher power, shaping the laser beam and reducing the focus shift are key.
We describe here a beam shaper compatible with industry standard equipment. The fully reflective design ease the heat evacuation leading to a reduced focus shift thanks to the absence of thermal gradient inside the optics, leading to better beam stability and process.
We demonstrate here the system capability to shape the input beam into an annular shape of high quality. The process tests are performed at multi-kW level up to 16kW with a high stability over the whole process. The process test results and the weld quality improvements are described for different materials.
12:15pm - 12:30pm
Laser-based manufacturing of ceramic matrix composites
1Fraunhofer IKTS, Germany; 2Fraunhofer IWS, Germany; 3Space Structures GmbH, Germany
Ceramic matrix composites (CMCs) are quasi-ductile ceramics with excellent high-temperature properties. The main area of application is in aircraft engines as a replacement for nickel-based superalloys. Besides the high cost of the fiber material, the production of CMCs is quite expensive as advanced furnace technology is required. Furthermore, the joining of CMC components is still insufficiently developed.
This paper presents a novel manufacturing process that uses a laser as a heat source to locally solidify the ceramic material by generating a transient liquid matrix phase. Material properties as well as microstructural investigations are shown. The process is classified with regard to potential areas of application.
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