Lucas Hille, Johannes Kriegler, Andreas Oehler, Michalina Chaja, Sebastian Wagner, Michael F. Zaeh
Laser structuring of graphite anodes substantially improves the electrochemical performance of lithium-ion batteries by facilitating lithium-ion diffusion through the electrode coatings. However, laser structuring is not yet established in industrial battery production due to limited knowledge of its ablation behavior and a low processing rate. This publication addresses these issues with a combination of experimental and theoretical approaches. In a comprehensive process study with picosecond pulsed laser radiation, the influence of various laser parameters on the obtained structure geometries, i.e., the hole diameters and depths, was examined. Wavelengths of 532 and 355 nm combined with pulse bursts and fluences of approximately 10 J cm−2 eventuated in favorable hole geometries with a high aspect ratio. Compared to singlebeam laser structuring, a nearly tenfold reduction in the processing time was achieved by beam splitting with a diffractive optical element without compromising structure geometries or mechanical electrode integrity. The experimental findings were used to model the scalability of electrode laser structuring, revealing the significant influence of the hole pattern and distance on the potential processing rate. Ultrashort pulsed laser powers in the kilowatt regime were found to be necessary to laser-structure electrodes at industrial processing rates resulting in estimated costs of roughly 1.96 $/kWh. The findings support the industrialization of laser electrode structuring for commercial lithium-ion battery production.
{"title":"Picosecond laser structuring of graphite anodes—Ablation characteristics and process scaling","authors":"Lucas Hille, Johannes Kriegler, Andreas Oehler, Michalina Chaja, Sebastian Wagner, Michael F. Zaeh","doi":"10.2351/7.0001087","DOIUrl":"https://doi.org/10.2351/7.0001087","url":null,"abstract":"Laser structuring of graphite anodes substantially improves the electrochemical performance of lithium-ion batteries by facilitating lithium-ion diffusion through the electrode coatings. However, laser structuring is not yet established in industrial battery production due to limited knowledge of its ablation behavior and a low processing rate. This publication addresses these issues with a combination of experimental and theoretical approaches. In a comprehensive process study with picosecond pulsed laser radiation, the influence of various laser parameters on the obtained structure geometries, i.e., the hole diameters and depths, was examined. Wavelengths of 532 and 355 nm combined with pulse bursts and fluences of approximately 10 J cm−2 eventuated in favorable hole geometries with a high aspect ratio. Compared to singlebeam laser structuring, a nearly tenfold reduction in the processing time was achieved by beam splitting with a diffractive optical element without compromising structure geometries or mechanical electrode integrity. The experimental findings were used to model the scalability of electrode laser structuring, revealing the significant influence of the hole pattern and distance on the potential processing rate. Ultrashort pulsed laser powers in the kilowatt regime were found to be necessary to laser-structure electrodes at industrial processing rates resulting in estimated costs of roughly 1.96 $/kWh. The findings support the industrialization of laser electrode structuring for commercial lithium-ion battery production.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135217890","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jason M. Gross, Seyedeh Reyhaneh Shavandi, Teodora Zagorac, Michael J. Pasterski, Luke Hanley
Laser ablation (LA) using nanosecond (ns) or femtosecond (fs) pulse widths is well-established for the volatilization of a liquid or solid for applications ranging from micromachining to sampling for compositional analysis. Far less work has examined laser ablation in the intermediate picosecond regime (ps-LA), which corresponds to the approximate timescale for the transfer of energy from laser-excited electrons to the lattice. 213 and 355 nm ps-LA of silicon (Si) with Gaussian beam profiles is compared here to 800 nm fs-LA with both Gaussian and flat-top beam profiles, all performed at or above the ablation threshold with 20 000–67 000 laser pulses. The morphology and composition of the ablation spots are examined using scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS), respectively. 213 nm ps-LA yields more visible nanostructures compared to those ablated by 355 nm ps-LA, but both form central craters with surrounding nanostructures due to resolidified material. The flat-top fs beam creates protruding nanostructures isolated near the rim of the crater and an inside-out umbrella-like structure at the center. The Gaussian fs-LA region displays a relatively smooth conical crater, albeit with some nanostructure at the rim of the crater. EDS finds that these nanostructures are at least partly composed of silicon oxide or suboxides. The invisibility of these nanostructures to optical profilometry is consistent with black-silicon. The ablation crater results from optical profilometry for 213 nm ps-LA are close to those for 800 nm flat-top fs-LA, and both are consistent with cylindrical craters.
{"title":"Picosecond versus femtosecond-laser ablation of silicon in atmosphere","authors":"Jason M. Gross, Seyedeh Reyhaneh Shavandi, Teodora Zagorac, Michael J. Pasterski, Luke Hanley","doi":"10.2351/7.0001206","DOIUrl":"https://doi.org/10.2351/7.0001206","url":null,"abstract":"Laser ablation (LA) using nanosecond (ns) or femtosecond (fs) pulse widths is well-established for the volatilization of a liquid or solid for applications ranging from micromachining to sampling for compositional analysis. Far less work has examined laser ablation in the intermediate picosecond regime (ps-LA), which corresponds to the approximate timescale for the transfer of energy from laser-excited electrons to the lattice. 213 and 355 nm ps-LA of silicon (Si) with Gaussian beam profiles is compared here to 800 nm fs-LA with both Gaussian and flat-top beam profiles, all performed at or above the ablation threshold with 20 000–67 000 laser pulses. The morphology and composition of the ablation spots are examined using scanning electron microscopy and energy dispersive x-ray spectroscopy (EDS), respectively. 213 nm ps-LA yields more visible nanostructures compared to those ablated by 355 nm ps-LA, but both form central craters with surrounding nanostructures due to resolidified material. The flat-top fs beam creates protruding nanostructures isolated near the rim of the crater and an inside-out umbrella-like structure at the center. The Gaussian fs-LA region displays a relatively smooth conical crater, albeit with some nanostructure at the rim of the crater. EDS finds that these nanostructures are at least partly composed of silicon oxide or suboxides. The invisibility of these nanostructures to optical profilometry is consistent with black-silicon. The ablation crater results from optical profilometry for 213 nm ps-LA are close to those for 800 nm flat-top fs-LA, and both are consistent with cylindrical craters.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135273968","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Three oscillation paths, namely, straight, sine, and circular, are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of the fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by using the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding circular path. Notably, numerical simulation results are validated through experimental data, and circular oscillating laser welding significantly reduced weld seam porosity in the welding of Ti–Al dissimilar alloys. The circular oscillation path with an offset of 0.6 mm and an oscillation amplitude of 0.6 mm is identified as the optimal approach for suppressing pores in the weld joint. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.
{"title":"Study of melt pool dynamics and porosity forming mechanism of laser beam oscillation welding of titanium and aluminum","authors":"Jinbo Yu, Jiahao Song, Xigui Xie, Jianxi Zhou","doi":"10.2351/7.0001069","DOIUrl":"https://doi.org/10.2351/7.0001069","url":null,"abstract":"In this study, a numerical model of oscillation weld butt joint is developed to investigate the welding of titanium alloy with aluminum alloy. Three oscillation paths, namely, straight, sine, and circular, are used to study the distribution of force in the molten pool, the welding temperature field, and the formation and evolution of porosity within the weld. A 3D Gaussian heat source is used to represent the laser beam. The volume of the fluid method is employed to track the gas-liquid free surface, and the gas-liquid interface force is transformed by using the continuous surface force model. The mechanism of keyhole collapse and pore formation was examined along with the fluid flow, surface tension, and recoil pressure on the molten pool. The results confirmed that the highest welding quality is acquired by using a laser welding circular path. Notably, numerical simulation results are validated through experimental data, and circular oscillating laser welding significantly reduced weld seam porosity in the welding of Ti–Al dissimilar alloys. The circular oscillation path with an offset of 0.6 mm and an oscillation amplitude of 0.6 mm is identified as the optimal approach for suppressing pores in the weld joint. This research provides valuable insights into the fundamental mechanisms of keyhole collapse and pore formation in laser welding, which contributes to the advancement of effective welding strategies for dissimilar alloys.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569515","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Fabian Bieg, David Scheider, Christian Kledwig, Clemens Maucher, Hans-Christian Möhring, Martin Reisacher
In today’s manufacturing, additive manufacturing processes enable the production of complicated three-dimensional structures that are hard to be manufactured with traditional manufacturing processes. Due to its high build rate, the laser-based directed energy deposition (DED-LB) process is an attractive and versatile process to manufacture these kinds of components. In addition to the production of components, DED-LB is used for repair or coating applications. The DED-LB process consists of a multitude of complex thermal mechanisms with high heating and cooling rates of 5 × 102 up to 5 × 105 K/s. For materials with high hardness or low thermal conductivity like tool steels, cast iron, or tungsten carbide, these high cooling rates can lead to defects in the microstructure like cracks, pores, or delamination between the substrate and the deposited structures. By preheating the substrate, the cooling rates can be reduced and defects can be eliminated. In this paper, a preheating cycle was developed, which uses the laser of a DMG MORI LT 65 DED hybrid machine as a moving heat source for the substrate preheating. For this cycle, process parameters, a tool path strategy, and a temperature control system were developed. The impact of the elaborated concept was shown by depositing tungsten carbide in a nickel matrix on an S235 steel substrate.
{"title":"Development of a laser preheating concept for directed energy deposition","authors":"Fabian Bieg, David Scheider, Christian Kledwig, Clemens Maucher, Hans-Christian Möhring, Martin Reisacher","doi":"10.2351/7.0001124","DOIUrl":"https://doi.org/10.2351/7.0001124","url":null,"abstract":"In today’s manufacturing, additive manufacturing processes enable the production of complicated three-dimensional structures that are hard to be manufactured with traditional manufacturing processes. Due to its high build rate, the laser-based directed energy deposition (DED-LB) process is an attractive and versatile process to manufacture these kinds of components. In addition to the production of components, DED-LB is used for repair or coating applications. The DED-LB process consists of a multitude of complex thermal mechanisms with high heating and cooling rates of 5 × 102 up to 5 × 105 K/s. For materials with high hardness or low thermal conductivity like tool steels, cast iron, or tungsten carbide, these high cooling rates can lead to defects in the microstructure like cracks, pores, or delamination between the substrate and the deposited structures. By preheating the substrate, the cooling rates can be reduced and defects can be eliminated. In this paper, a preheating cycle was developed, which uses the laser of a DMG MORI LT 65 DED hybrid machine as a moving heat source for the substrate preheating. For this cycle, process parameters, a tool path strategy, and a temperature control system were developed. The impact of the elaborated concept was shown by depositing tungsten carbide in a nickel matrix on an S235 steel substrate.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135569517","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sarah Nothdurft, Oliver Seffer, Jörg Hermsdorf, Stefan Kaierle
Nowadays, battery-electric drives and energy storage are elected to be the future technologies. In the manufacturing of parts for electric applications, laser beam welding is an appropriate and favorable welding method. The characteristics of high welding speed, local heat input, and the contact-free process allow efficient and automatable processes. For electrodes, mainly copper and aluminum are used. Many foils with thicknesses of an area of 10 μm have to be connected to create battery cells. Different than expected, aluminum is a more challenging material to produce than others. Pore formation is also extended in aluminum due to the presence of air between the foils. The connecting cross section is thereby reduced. Furthermore, there is detachment in the fusion area and a high weld seam undercut. In addition to insufficient clamping, a lack of material reduces strength and, thus, usability. In the research presented here, the use of aluminum filler wire (AA 1050A) and shielding gas are investigated for the application of welding 40 aluminum foils (AA 1050A) with a thickness of 15 μm to an aluminum sheet with a thickness of 2 mm using infrared laser beam wavelength. The aims of the process development are welds with high connection widths and high quality as well as reproducibility to provide excellent mechanical properties and the highest electrical conductivity.
{"title":"Investigations on laser beam welding of thin aluminum foils with additional filler wire","authors":"Sarah Nothdurft, Oliver Seffer, Jörg Hermsdorf, Stefan Kaierle","doi":"10.2351/7.0001160","DOIUrl":"https://doi.org/10.2351/7.0001160","url":null,"abstract":"Nowadays, battery-electric drives and energy storage are elected to be the future technologies. In the manufacturing of parts for electric applications, laser beam welding is an appropriate and favorable welding method. The characteristics of high welding speed, local heat input, and the contact-free process allow efficient and automatable processes. For electrodes, mainly copper and aluminum are used. Many foils with thicknesses of an area of 10 μm have to be connected to create battery cells. Different than expected, aluminum is a more challenging material to produce than others. Pore formation is also extended in aluminum due to the presence of air between the foils. The connecting cross section is thereby reduced. Furthermore, there is detachment in the fusion area and a high weld seam undercut. In addition to insufficient clamping, a lack of material reduces strength and, thus, usability. In the research presented here, the use of aluminum filler wire (AA 1050A) and shielding gas are investigated for the application of welding 40 aluminum foils (AA 1050A) with a thickness of 15 μm to an aluminum sheet with a thickness of 2 mm using infrared laser beam wavelength. The aims of the process development are welds with high connection widths and high quality as well as reproducibility to provide excellent mechanical properties and the highest electrical conductivity.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135778936","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This study investigated the effects of laser beam intensity distribution on the reduction of dross height in fiber laser cutting of a steel plate with 3.2 mm thickness. A twin-spot beam was produced by splitting a single Gaussian beam into two beams using a special axicon lens, and these beams were set in the scanning direction for cutting experiments. The power ratio of two beams (R:F = Rear power:Front power) was varied to discuss the intensity balance for the effective reduction of dross. After cutting experiments, ray tracing analysis was conducted using an optical analysis to calculate the absorbed power density distributions in the kerf. A smaller dross height of 18 μm can be achieved at a power ratio of R:F = 8:2, and its value is lower than that by a single Gaussian beam. At a power ratio of R:F = 8:2, the front beam of lower power is irradiated at the upper part of the workpiece, and the rear beam of higher power is absorbed at the lower part of the workpiece. Thus, effective heat input to the lower part of the workpiece can contribute to a reduction of the dross height. Variation of power ratio in the rear and the front beams is effective in controlling the cutting front shape, and the uniformity of absorbed power in the thickness direction can be improved by setting the rear beam of about four times higher power to the front beam of lower power to obtain a smaller dross height in the case of a 3.2 mm steel plate.
{"title":"Fiber laser cutting of steel plate by twin spot beam setting in scanning direction","authors":"Yasuhiro Okamoto, Kota Morimoto, Naoki Kai, Akira Okada, Hiroaki Ishiguro, Ryohei Ito, Hiroshi Okawa","doi":"10.2351/7.0001097","DOIUrl":"https://doi.org/10.2351/7.0001097","url":null,"abstract":"This study investigated the effects of laser beam intensity distribution on the reduction of dross height in fiber laser cutting of a steel plate with 3.2 mm thickness. A twin-spot beam was produced by splitting a single Gaussian beam into two beams using a special axicon lens, and these beams were set in the scanning direction for cutting experiments. The power ratio of two beams (R:F = Rear power:Front power) was varied to discuss the intensity balance for the effective reduction of dross. After cutting experiments, ray tracing analysis was conducted using an optical analysis to calculate the absorbed power density distributions in the kerf. A smaller dross height of 18 μm can be achieved at a power ratio of R:F = 8:2, and its value is lower than that by a single Gaussian beam. At a power ratio of R:F = 8:2, the front beam of lower power is irradiated at the upper part of the workpiece, and the rear beam of higher power is absorbed at the lower part of the workpiece. Thus, effective heat input to the lower part of the workpiece can contribute to a reduction of the dross height. Variation of power ratio in the rear and the front beams is effective in controlling the cutting front shape, and the uniformity of absorbed power in the thickness direction can be improved by setting the rear beam of about four times higher power to the front beam of lower power to obtain a smaller dross height in the case of a 3.2 mm steel plate.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135885071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In laser metal deposition (LMD), the powder is fed into the laser-induced melt pool using different powder nozzles for the purpose of additive manufacturing and the generation of wear and corrosion protection coatings. So far, there are no industrially established in-process monitoring systems for the powder stream but mainly measuring systems that examine the powder stream propagation offline and without the processing laser. A challenge in implementing an image-based in-process monitoring system is the process illumination for the distinction of the powder particles from the background radiation caused by the processing laser and the melt pool. To overcome this challenge, filtering is needed to attenuate the process emissions and simultaneously brighten the powder stream. Therefore, this work focuses on generating a continuous high contrast between the powder and the background. The powder particles are illuminated by a light source mounted laterally to the powder stream in the horizontal plane below the nozzle opening to make the reflecting powder particles visible to the camera. The optical process emissions were characterized during LMD with respect to the influence of an increasing laser power, which was presented in correlation to the increasing process emissions. The evaluation of the spectrograms has made it possible, due to the adapted illumination and filtering, to ensure a constantly high contrast between the process emissions and the powder so that online monitoring of the powder stream was implemented successfully during the LMD process despite the active processing laser.
{"title":"Characterization of optical emissions during laser metal deposition for the implementation of an in-process powder stream monitoring","authors":"Philipp Hildinger, Thomas Seefeld, Annika Bohlen","doi":"10.2351/7.0001161","DOIUrl":"https://doi.org/10.2351/7.0001161","url":null,"abstract":"In laser metal deposition (LMD), the powder is fed into the laser-induced melt pool using different powder nozzles for the purpose of additive manufacturing and the generation of wear and corrosion protection coatings. So far, there are no industrially established in-process monitoring systems for the powder stream but mainly measuring systems that examine the powder stream propagation offline and without the processing laser. A challenge in implementing an image-based in-process monitoring system is the process illumination for the distinction of the powder particles from the background radiation caused by the processing laser and the melt pool. To overcome this challenge, filtering is needed to attenuate the process emissions and simultaneously brighten the powder stream. Therefore, this work focuses on generating a continuous high contrast between the powder and the background. The powder particles are illuminated by a light source mounted laterally to the powder stream in the horizontal plane below the nozzle opening to make the reflecting powder particles visible to the camera. The optical process emissions were characterized during LMD with respect to the influence of an increasing laser power, which was presented in correlation to the increasing process emissions. The evaluation of the spectrograms has made it possible, due to the adapted illumination and filtering, to ensure a constantly high contrast between the process emissions and the powder so that online monitoring of the powder stream was implemented successfully during the LMD process despite the active processing laser.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136114678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Karim Asami, Sebastian Roth, Michel Krukenberg, Tim Röver, Dirk Herzog, Claus Emmelmann
Lattice structures in additive manufacturing of 316L stainless steel have gained increasing attention due to their well-suited mechanical properties and lightweight characteristics. Infill structures such as honeycomb, lattice, and gyroid have shown promise in achieving desirable mechanical properties for various applications. However, the design process of these structures is complex and time-consuming. In this study, we propose a machine learning-based approach to optimize the design of honeycomb, lattice, and gyroid infill structures in 316L stainless steel fabricated using laser powder bed fusion (L-PBF) technology under different loading conditions. A dataset of simulated lattice structures with varying geometries, wall thickness, distance, and angle using a computational model that simulates the mechanical behavior of infill structures under different loading conditions was generated. The dataset was then used to train a machine learning model to predict the mechanical properties of infill structures based on their design parameters. Using the trained machine learning model, we then performed a design exploration to identify the optimal infill structure geometry for a given set of mechanical requirements and loading conditions. Finally, we fabricated the optimized infill structures using L-PBF technology and conducted a series of mechanical tests to validate their performance under different loading conditions. Overall, our study demonstrates the potential of machine learning-based approaches for efficient and effective designing of honeycomb, lattice, and gyroid infill structures in 316L stainless steel fabricated using L-PBF technology under different loading conditions. Furthermore, this approach can be used for dynamic loading studies of infill structures.
{"title":"Predictive modeling of lattice structure design for 316L stainless steel using machine learning in the L-PBF process","authors":"Karim Asami, Sebastian Roth, Michel Krukenberg, Tim Röver, Dirk Herzog, Claus Emmelmann","doi":"10.2351/7.0001174","DOIUrl":"https://doi.org/10.2351/7.0001174","url":null,"abstract":"Lattice structures in additive manufacturing of 316L stainless steel have gained increasing attention due to their well-suited mechanical properties and lightweight characteristics. Infill structures such as honeycomb, lattice, and gyroid have shown promise in achieving desirable mechanical properties for various applications. However, the design process of these structures is complex and time-consuming. In this study, we propose a machine learning-based approach to optimize the design of honeycomb, lattice, and gyroid infill structures in 316L stainless steel fabricated using laser powder bed fusion (L-PBF) technology under different loading conditions. A dataset of simulated lattice structures with varying geometries, wall thickness, distance, and angle using a computational model that simulates the mechanical behavior of infill structures under different loading conditions was generated. The dataset was then used to train a machine learning model to predict the mechanical properties of infill structures based on their design parameters. Using the trained machine learning model, we then performed a design exploration to identify the optimal infill structure geometry for a given set of mechanical requirements and loading conditions. Finally, we fabricated the optimized infill structures using L-PBF technology and conducted a series of mechanical tests to validate their performance under different loading conditions. Overall, our study demonstrates the potential of machine learning-based approaches for efficient and effective designing of honeycomb, lattice, and gyroid infill structures in 316L stainless steel fabricated using L-PBF technology under different loading conditions. Furthermore, this approach can be used for dynamic loading studies of infill structures.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858383","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Filofteia-Laura Toma, Holger Hillig, Marc Kaubisch, Irina Shakhverdova, Marko Seifert, Frank Brueckner
Laser cladding is widely used in the industry to precisely apply tailored surface coatings, as well as three-dimensional deposits for repair and additive manufacturing of metallic parts. However, the processing of larger components is economically challenging mainly because of low deposition rates. At Fraunhofer IWS, a Laserline fiber-coupled diode laser with 20 kW power has been employed for over a decade to develop competitive coating solutions with powder-based laser cladding. The deposition rates achieved with this technology is comparable to common PTA technique at the same time bringing significant advantages in terms of reduced heat affected zone, distortion, and savings in material resources. While high-power powder-based laser cladding is an industrially established coating technology, for example, to coat hydraulic cylinders or most recently brake discs, a high-productivity solution for wire-based processes is still challenging. Fraunhofer IWS has developed a new nozzle for high-power high-productivity laser wire cladding for coating and additive manufacturing, the so-called COAXquattro. This system enables to feed at the same time four wires into the melt pool, reaching deposition efficiencies in the same range as a powder-based laser process. For selected materials, the improvement in coating quality compared to powder laser cladding is achieved. Furthermore, with COAXquattro system simultaneous feeding of powder particles to wire cladding presents a great potential for in situ alloying and cost-effective production of new compositions on material alloying or hardmetal-reinforced composites for coating application and 3D additive manufacturing.
{"title":"Latest developments in coaxial multiwire high-power laser cladding","authors":"Filofteia-Laura Toma, Holger Hillig, Marc Kaubisch, Irina Shakhverdova, Marko Seifert, Frank Brueckner","doi":"10.2351/7.0001138","DOIUrl":"https://doi.org/10.2351/7.0001138","url":null,"abstract":"Laser cladding is widely used in the industry to precisely apply tailored surface coatings, as well as three-dimensional deposits for repair and additive manufacturing of metallic parts. However, the processing of larger components is economically challenging mainly because of low deposition rates. At Fraunhofer IWS, a Laserline fiber-coupled diode laser with 20 kW power has been employed for over a decade to develop competitive coating solutions with powder-based laser cladding. The deposition rates achieved with this technology is comparable to common PTA technique at the same time bringing significant advantages in terms of reduced heat affected zone, distortion, and savings in material resources. While high-power powder-based laser cladding is an industrially established coating technology, for example, to coat hydraulic cylinders or most recently brake discs, a high-productivity solution for wire-based processes is still challenging. Fraunhofer IWS has developed a new nozzle for high-power high-productivity laser wire cladding for coating and additive manufacturing, the so-called COAXquattro. This system enables to feed at the same time four wires into the melt pool, reaching deposition efficiencies in the same range as a powder-based laser process. For selected materials, the improvement in coating quality compared to powder laser cladding is achieved. Furthermore, with COAXquattro system simultaneous feeding of powder particles to wire cladding presents a great potential for in situ alloying and cost-effective production of new compositions on material alloying or hardmetal-reinforced composites for coating application and 3D additive manufacturing.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135858731","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Jorge Sanchez-Medina, Dieter De Baere, Charles Snyers, Zoé Jardon, Michaël Hinderdael, Julien Ertveldt, Patrick Guillaume
Directed energy deposition is an additive manufacturing process that allows the production of near net shape structures. Moreover, the process can also be applied for the repair of high value components. To obtain structures with consistent good characteristics, the directed energy deposition process requires the implementation of a control system. The currently applied approaches for control that are discussed in the literature have specifically focused on melt-pool temperature control. Pyrometers have been used for such purposes; however, they provide only a single scalar value without any spatial information. In this paper, the implementation of a high-speed hyperspectral camera-based system is discussed with a high spatial resolution unlike the pyrometers. Different calibration and temperature estimation procedures for this camera-based system are evaluated and analyzed. The number of effective wavelengths needed for temperature estimation will be discussed in detail and provide an outlook on the potential of this hyperspectral camera-based system. In addition to the number of wavelengths, another important aspect of the temperature estimation methods is the stability with respect to disturbances. Within this paper, the impact of the nominal laser power will be evaluated on the stability of the temperature signals for a control system.
{"title":"Comparison and analysis of hyperspectral temperature data in directed energy deposition","authors":"Jorge Sanchez-Medina, Dieter De Baere, Charles Snyers, Zoé Jardon, Michaël Hinderdael, Julien Ertveldt, Patrick Guillaume","doi":"10.2351/7.0001074","DOIUrl":"https://doi.org/10.2351/7.0001074","url":null,"abstract":"Directed energy deposition is an additive manufacturing process that allows the production of near net shape structures. Moreover, the process can also be applied for the repair of high value components. To obtain structures with consistent good characteristics, the directed energy deposition process requires the implementation of a control system. The currently applied approaches for control that are discussed in the literature have specifically focused on melt-pool temperature control. Pyrometers have been used for such purposes; however, they provide only a single scalar value without any spatial information. In this paper, the implementation of a high-speed hyperspectral camera-based system is discussed with a high spatial resolution unlike the pyrometers. Different calibration and temperature estimation procedures for this camera-based system are evaluated and analyzed. The number of effective wavelengths needed for temperature estimation will be discussed in detail and provide an outlook on the potential of this hyperspectral camera-based system. In addition to the number of wavelengths, another important aspect of the temperature estimation methods is the stability with respect to disturbances. Within this paper, the impact of the nominal laser power will be evaluated on the stability of the temperature signals for a control system.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136012589","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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