United States

Solidification cracking is one of the most critical weld defects in laser welding of Al 6000 alloys. It occurs at the end stage of solidification due to the shrinkage of weld metal and deteriorates the joint strength and integrity. Filler metal can control the chemical composition of weld metal, which mitigates the solidification cracking; however, the chemical composition is difficult to control in autogenous laser welding. Temporal/spatial laser beam modulations have been introduced to control the solidification cracking in autogenous laser welding because the welds morphology is one of the factors that influence the solidification cracking initiation and propagation. Solidification cracks generate thermal discontinuity and visual flaws on the bead surface. In this study, a high-speed infrared (IR) camera and a coaxial charge-coupled device (CCD) camera with an auxiliary illumination laser (808 nm) were employed to identify solidification cracking during laser welding. Deep learning models were developed using two sensor images of the solidified bead. The output of deep learning models were location-wise cracking formation. Convolution neural network (CNN)-based deep learning models showed excellent cracking identification accuracies. In this study, the multiple sensor system of high-speed IR camera and low-cost CCD camera demonstrated its capability and potential in laser welding inspection.

ICALEO 2023

Identification of Solidification Cracking Using Multiple Sensors and Deep Learning in Laser Overlap Welded Al 6000 Alloy

ccd camera

ir camera

solidification cracking

al alloy laser welidng

deep learning

poster

**General Chair Welcome**

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Welcome to ICALEO® 2023!
	
We were excited to host the world’s leading international conference on Lasers and Electro-Optics in Chicago. The Laser has been shown to have the potential to revolutionize solutions for major global challenges like energy usage and supply, global warming, and CO2 footprint. Even the fusion energy breakthrough is based on laser technology. The conference, with peer-reviewed scientific and technical presentations, focused on the newest results in Micro Applications, Macro Applications, Additive Manufacturing, Beam Shaping and Frontiers in Laser Applications. Additionally, the Battery-Manufacturing Track gave an overview of the process combined with the newest advances in laser application results. 

The Business Session brought the business aspect and environment of the laser to the audience and the possibility to discuss with seasoned industry leaders from around the world. 

Whether this is the first time you are hearing about ICALEO or you are a longtime attendee, you will find something of interest, new ideas, and an excellent opportunity to network with other laser specialists worldwide. 

**Klaus Löffler **  
ICALEO General Chair   
Managing Director, Precitec GmbH

**What is ICALEO?**

ICALEO® brings together the brightest minds, seasoned professionals, and pioneering researchers from around the world. With a laser-focused agenda, ICALEO offers an exceptional platform to delve into the cutting-edge advancements, diverse applications, and transformative research that define lasers and electro-optics.

Participants will be immersed in a dynamic environment that fosters collaborative learning, networking, and idea exchange. Through engaging plenary presentations, technical sessions, an industry business panel, and networking events, attendees gain insights into the forefront of laser technology. From industrial applications to medical breakthroughs, additive manufacturing to materials processing, ICALEO covers the entire spectrum of laser-related disciplines. Moreover, the event serves as a launching pad for synergistic partnerships, paving the way for professionals to forge connections that shape the future of our industry.

Join us in Chicago and be part of an unparalleled gathering that challenges the boundaries of possibility within lasers and electro-optics. As we convene to share knowledge, explore innovations, and cultivate collaborations, ICALEO stands as a pivotal force driving the evolution of this transformative technology.

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ICALEO is tailor-made for professionals, researchers, academics, and enthusiasts who are deeply passionate about the world of lasers and electro-optics. If you're an industry trailblazer, an academic luminary, an aspiring expert, or a postgraduate student looking to dive into the latest developments and trends, this is an event you won't want to miss.

Industrial leaders seeking to stay ahead of the curve in their fields, engineers working on laser applications, and manufacturing experts interested in additive manufacturing and materials processing will find ICALEO to be an invaluable platform. Researchers and scientists exploring the forefront of laser technology, from fundamental principles to groundbreaking applications, will also discover a wealth of knowledge and networking opportunities.

Medical professionals investigating laser-based medical advancements, entrepreneurs seeking to innovate with lasers, educators aiming to stay updated with the latest in laser education, and policy makers shaping the industry's landscape are all essential attendees. Whether you're an established expert or a rising star, the 42nd annual ICALEO promises to offer a diverse ecosystem of expertise, connections, and knowledge sharing that caters to the laser and electro-optics communities.

**Fields Represented:**

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Please register for the ICALEO 2023 Conference to join the event.

ICALEO® brings together the brightest minds, seasoned professionals, and pioneering researchers from around the world. With a laser-focused agenda, ICALEO offers an exceptional platform to delve into the cutting-edge advancements, diverse applications, and transformative research that define lasers and electro-optics.

Global initiatives and legal frameworks to achieve net-zero carbon emissions will require the development of manufacturing processes significantly different from current commercial methods. The efficiency and fine control of laser-material interactions have proven themselves as disruptive manufacturing technologies that are ideally suited to replace conventional thermal processes. Conventional textile dyeing is known to be resource-intensive, relying on slow-acting thermal dye-fixation processes. These are inherently inefficient as they indirectly heat the material's surface through steam chambers or boiling vats to chemically fixate the dye onto the fabric, resulting in large lag system responses. The typical system response time for these manufacturing processes is minutes, which equates to a work-in-progress of hundreds of linear metres of product. This paper presents a method of directly heating the textile surface with a Continuous Wave CO2 laser in combination with existing commercially available Polyamide textiles and Nylosan Acid Dye. Results from this new process show that the essential industrial quality control standards for colour fastness and mechanical properties are maintained. The key finding discussed in this paper is that using a laser source to provide a direct and rapid heating mechanism at the site of dye fixation enables the implementation of a fast response system. The heating control of the laser is effectively instantaneous, at &lt;100 µs, resulting in control responses that affect less than one linear metre of material. The results presented here represent a product family with annual manufacturing volumes of 1.5 billion meters of textile, creating potential for significant improvements to manufacturing.

Rapid Response Textile Dyeing: A Laser-enabled Manufacturing Process

Additive manufacturing is an enticing way for producing complex geometries and optimized parts for special applications. Even though the achievable static properties for the printed material are usually good when compared to wrought materials, in many cases dynamic properties are known to be much worse. Often the quality is sacrificed in respect of printing speed. Further, printed materials have usually anisotropic behavior, caused by the remelting and fast cooling of each deposited layer. This means that the mechanical properties are needed to be measured in several directions in respect of the printing direction for attaining a more holistic approach on the achieved static and dynamic behavior. As a demonstration, this study focuses on determining the properties of 316L stainless steel manufactured with laser powder bed fusion. Comprehensive set of samples for various testing methods were manufactured to investigate the effect of layer thickness and printing orientation on the microstructure, mechanical properties, impact strength and fatigue life. Fatigue performance of the material was evaluated both in axial and flexural bending comparing as built and polished surface conditions. Bending fatigue testing revealed that a fatigue limit of 100 MPa at best can be achieved with the as built surface quality, but with a polished surface and lower layer thickness it could be doubled. Impact toughness and mechanical strength of the material are heavily dependent on the layer thickness and while the best results were obtained with the lower layer thickness the printing orientation can have a detrimental effect on it.

Fatigue Strength and Impact Toughness Dependence of PBF-LB Manufactured 316L Stainless Steel on Orientation and Layer Thickness

Laser Powder Bed Fusion (LPBF) is a critical additive manufacturing process for producing complex parts with high accuracy and precision. However, LPBF faces significant challenges in increasing the process yield and printing new powders while reducing hot cracking. These challenges limit the production speed, reduce the manufacturing efficiency, and restrict the range of materials that can be used in LPBF. 
Beam shaping offers a potential solution to overcome these challenges by modifying the laser beam's intensity distribution. In this paper, we explore the application of Multi-Plane Light Conversion (MPLC) to LPBF to improve the process speed and quality. MPLC is a novel beam-shaping technique that enables the creation of complex intensity profiles by redirecting the laser beam through multiple planes of phase modulators. 
Our study demonstrates the successful application of MPLC to LPBF, enabling a significant increase in the process speed while maintaining high-quality parts. We use an appropriate ring shape for printing the inner part and a small Gaussian beam for the contour of the part. We compare the performance with no beam shaping as well as with beam shaping based on shaping within the fiber of the laser technology. Our results show that MPLC-based beam shaping improves the process yield, leading to faster printing and improved manufacturing efficiency.

Process Speed Increase in Laser Powder Bed Fusion Thanks to Beam Shaping with Multi-Plane Light Conversion

The accelerated electrification of vehicles boosts the demand for sustainable batteries with enhanced energy density. Lithium metal anodes are expected to be a key component for future generation energy storage such as solid state and Lithium sulfur batteries. Energy consumption needs to be further reduced in cell production and substituting the wet electrode processing will be a major step in this direction. As a consequence, innovations in production technologies are required for the manufacturing of future generation batteries. 
Here, we present new concepts for manufacturing of Lithium metal batteries, including coating, cutting and contacting of Lithium anodes as well as dry film processing of composite cathodes. A unique melt deposition process is applied for achieving few micrometer thin Lithium metal films on current collector foils. Further, a laser-based cutting process enables the flexible shaping of Lithium foils and coatings with high edge quality. For direct contacting of Lithium anodes to tabs a low contact resistance and high mechanical strength is achieved via Laser beam joining. Composite cathodes based on various active materials are being produced via the solvent free process DRYtraec®. All process steps are implemented in a semi-automated cell assembly line at Fraunhofer IWS for manufacturing and evaluating Lithium metal battery cells. Thus, the developed technology concepts are being demonstrated in high energy battery cell prototypes exceeding a specific energy of 400 Wh/kg.

Processing Future Generation of Battery Electrodes with Advanced Laser and Coating Technologies

This abstract and keynote speech addresses the challenges in the development of additive manufacturing (AM) using selective laser melting (SLM) technology. With this technique, AM can produce superior and sustainable parts by the application of bionic design. In the last two decades L-PBF increased it’s productivity by a factor of 200, however it still misses commercial competitiveness. One of the main current bottlenecks lies in the high production costs of more than €1000 per kilogram of manufactured 
material. These have their cause mainly in inefficient build up rates and expensive powder costs. Another constraint is the need for ensuring consistent and high-quality parts, requiring a certified quality assurance process. 
To address these challenges, we developed a project idea whose goal it is to develop an optimized AM product by integrating a ring-mode laser as well as a manufacturing monitoring system for quality assurance and faster build rates. The ultimate goal is to achieve a certified and profitable product with target costs of less than €100 per kilogram of certified material to be competitive in the market. 
The proposed solution aims to improve the efficiency of the SLM process, resulting in lower production costs and faster production rates, while maintaining consistent high-quality parts. The ring-mode laser provides more uniform energy distribution and reduces thermal gradients, improving the material properties and reducing distortion int the manufactured part. This will move the threshold for the maximum robust melting productivity by a factor of ten due to higher laser scanning speeds and an improved layer thickness. 
The planned manufacturing monitoring system which is combined with quick destructive dynamic specimen testing ensures consistent quality while detecting and correcting any defects during production. This allows the approval of static and fatigue material properties with the certified absence of pores with a diameter bigger than 0.1 mm. 
The optimized SLM process which will be developed in this project idea could enable a more cost-effective production of metal parts and reduce the entry barriers for small and medium-sized corporations. Overall, the proposed solution could enhance the metal additive manufacturing industry, enabling competitive and sustainable production of high-quality metal parts for all kinds of applications.

Profitable and Certified Metal 3D Printing

Technological developments are elementary in the production of an electric car and especially in the battery production in order to increase competitiveness. For this reason, research institutes such as the „Chair of Production Engineering of E-Mobility Components“ and the “Fraunhofer Research Institution for Battery Cell Production FFB” executing technology screenings. Based on the results of the technology screening and the requirements of the industry, process developments are carried out. In the presentation, the findings of Fraunhofer FFB’s comprehensive study analyzing the potential of laser applications in battery production will be presented. The spotlight will be placed on relevant laser applications that have been identified in battery cell production, module manufacturing, and pack assembly. The example of laser drying for electrodes is then used to illustrate the ongoing process developments.

Innovative Uses of Lasers for Advancing Battery Production

Indirect-drive Inertial Confinement Fusion (ICF) experiments on the National Ignition Facility (NIF) have, for the first time, demonstrated fusion ignition in the laboratory. This milestone occurred&nbsp;for the first time&nbsp;in an experiment conducted on December 5 th , 2022, releasing 3.15 MJ of energy from the deuterium-tritium (DT) fusion reaction using 2.05 MJ of laser energy&nbsp;for a target gain of 1.5. This talk will describe&nbsp;this and more recent ignition&nbsp;experiments, chronicle some of the important scientific and technological developments that contributed to the increase in experimental fusion energy output that occurred between 2011 and today, and the prospects of harnessing fusion in the laboratory as an energy source.

Achieving Ignition on the National Ignition Facility

ICALEO Welcome Ceremony and Opening Plenary

The spatial laser energy absorption inside the keyhole is decisive for the dynamic molten pool behaviors and the resultant weld properties in high-power laser beam welding. In this paper, a numerical simulation of the LBW process, considering the 3D transient heat transfer, fluid flow and keyhole dynamics, is implemented, in which the free surface is tracked by the volume-of-fluid algorithm. The underlying laser-material interactions i.e., the multiple reflections and Fresnel absorption, are considered by an advanced ray-tracing method based on a localized Level-Set strategy. The laser energy absorption is analyzed from a time-averaged point of view for a better statistical representation. It is found for the first time that a noticeable drop of the time-averaged laser energy absorption occurs at the focal position of the laser beam, and the rest region of the keyhole has relatively homogenous absorbed energy. This unique absorption pattern may lead to a certain keyhole instability and have a strong correlation with the detrimental narrowing phenomenon in the molten pool. The influence of the different focal positions of the laser beam on the keyhole dynamics and weld pool profile is also analyzed and compared. The obtained numerical results are compared with experimental measurements to assure the validity of the proposed model.

The Influence of the Spatial Laser Energy Absorption of the Molten Pool Dynamics In High-Power Laser Beam Welding

Today, welding of quartz glass is mainly carried out with gas torches and by hand. The use of gas torches means that a lot of energy gets lost in the actual process zone. In addition, the manual process can result in inhomogeneous weld seams. 
An automated laser process would make the quartz glass welding process more energy efficient and more repeatable. In this study, quartz glass plates up to 4.5 mm in thickness are welded together at an angle of 125° using filler materials. The purpose is to achieve a homogeneous weld (V-seam) with as few defects as possible using a lateral fiber or rod based deposition welding process. 
The main challenge is to get the melt to the contact point of the two glasses so that no air inclusions occur. A 400 µm fiber and a 1 mm rod are investigated as additional materials. The advantage of the fiber compared to the rod is that the lower area (contact point of the glasses) is easier to reach during the welding process. The disadvantage is that a very high fiber feed rate is required to fill the gap. This leads to a high consumption of filler material. Process parameters include the substrate to fiber feed ratio, laser power, spot diameter, and process gas pressure and angle. The samples are analyzed using an optical microscope and a laser confocal microscope.&nbsp;Preliminary studies have shown that comparable results can be achieved with both filler materials.

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Identification of Solidification Cracking Using Multiple Sensors and Deep Learning in Laser Overlap Welded Al 6000 Alloy

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