Pascal Paulus, Yannick Ruppert, Michael Vielhaber, Juergen Griebsch
Powder-based laser metal deposition (LMD) offers a promising additive manufacturing process, given the large number of available materials for cladding or generative applications. In laser cladding of dissimilar materials, it is necessary to control the mixing of substrate and additive in the interaction zone to ensure safe metallurgical bonding while avoiding critical chemical compositions that lead to undesired phase precipitation. However, the generation of empirical data for LMD process development is very challenging and time-consuming. In this context, different machine learning models are examined to identify whether they can converge with a small amount of empirical data. In this work, the prediction accuracy of back propagation neural network (BPNN), long short-term memory (LSTM), and extreme gradient boosting (XGBoost) was compared using mean squared error (MSE) and mean absolute percentage error (MAPE). A hyperparameter optimization was performed for each model. The materials used are 316L as the substrate and VDM Alloy 780 as the additive. The dataset used consists of 40 empirically determined values. The input parameters are laser power, feed rate, and powder mass flow rate. The quality characteristics of height, width, dilution, Fe-amount, and seam contour are defined as outputs. As a result, the predictions were compared with retained validation data and described as MSE and MAPE to determine the prediction accuracy for the models. BPNN achieved a prediction accuracy of 0.0072 MSE and 4.37% MAPE and XGBoost of 0.0084 MSE and 6.34% MAPE. The most accurate prediction was achieved by LSTM with 0.0053 MSE and 3.75% MAPE.
{"title":"Prediction of single track clad quality in laser metal deposition using dissimilar materials: Comparison of machine learning-based approaches","authors":"Pascal Paulus, Yannick Ruppert, Michael Vielhaber, Juergen Griebsch","doi":"10.2351/7.0001108","DOIUrl":"https://doi.org/10.2351/7.0001108","url":null,"abstract":"Powder-based laser metal deposition (LMD) offers a promising additive manufacturing process, given the large number of available materials for cladding or generative applications. In laser cladding of dissimilar materials, it is necessary to control the mixing of substrate and additive in the interaction zone to ensure safe metallurgical bonding while avoiding critical chemical compositions that lead to undesired phase precipitation. However, the generation of empirical data for LMD process development is very challenging and time-consuming. In this context, different machine learning models are examined to identify whether they can converge with a small amount of empirical data. In this work, the prediction accuracy of back propagation neural network (BPNN), long short-term memory (LSTM), and extreme gradient boosting (XGBoost) was compared using mean squared error (MSE) and mean absolute percentage error (MAPE). A hyperparameter optimization was performed for each model. The materials used are 316L as the substrate and VDM Alloy 780 as the additive. The dataset used consists of 40 empirically determined values. The input parameters are laser power, feed rate, and powder mass flow rate. The quality characteristics of height, width, dilution, Fe-amount, and seam contour are defined as outputs. As a result, the predictions were compared with retained validation data and described as MSE and MAPE to determine the prediction accuracy for the models. BPNN achieved a prediction accuracy of 0.0072 MSE and 4.37% MAPE and XGBoost of 0.0084 MSE and 6.34% MAPE. The most accurate prediction was achieved by LSTM with 0.0053 MSE and 3.75% MAPE.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135696500","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}
Haixing Liu, Jie Xu, Haojian He, Chao Wu, Jing Liu, Xiuquan He, Xizhao Wang
Micropores fabricated on organic polymer films have a wide range of applications in fields such as microfiltration, new energy, and biomedical separation. The use of laser processing technology can complete the processing of micropores on the surface of ultrathin films with high precision, but there is still some difficulty in the processing of ultrathick films. In this paper, a picosecond ultraviolet (UV) laser was used to explore the high-precision manufacturing process of micropores on the surface of ultrathick polyimide (PI) films. The effects of laser power, laser frequency, and scanning speed on the cone angle and spatter deposition area of micropores’ fabrication on ultrathick PI were studied based on orthogonal experiments. The mechanism of processing micropores on ultrathick PI was analyzed by studying the deposition area and morphology of the spatter generated during the laser ablation process. It was found that high-quality micropores can be fabricated at low laser frequency and high power.
{"title":"Optimization of micropore fabrication on the surface of ultrathick polyimide film based on picosecond UV laser","authors":"Haixing Liu, Jie Xu, Haojian He, Chao Wu, Jing Liu, Xiuquan He, Xizhao Wang","doi":"10.2351/7.0001070","DOIUrl":"https://doi.org/10.2351/7.0001070","url":null,"abstract":"Micropores fabricated on organic polymer films have a wide range of applications in fields such as microfiltration, new energy, and biomedical separation. The use of laser processing technology can complete the processing of micropores on the surface of ultrathin films with high precision, but there is still some difficulty in the processing of ultrathick films. In this paper, a picosecond ultraviolet (UV) laser was used to explore the high-precision manufacturing process of micropores on the surface of ultrathick polyimide (PI) films. The effects of laser power, laser frequency, and scanning speed on the cone angle and spatter deposition area of micropores’ fabrication on ultrathick PI were studied based on orthogonal experiments. The mechanism of processing micropores on ultrathick PI was analyzed by studying the deposition area and morphology of the spatter generated during the laser ablation process. It was found that high-quality micropores can be fabricated at low laser frequency and high power.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135697302","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}
The spatter is one of the defect factors for laser welding. For high-quality laser welding, the elucidation of the spatter reduction mechanism is required. In our previous study, it was elucidated that the molten pool and keyhole fluctuation contribute to spatter generation from the observation of the keyhole and molten pool under different ambient pressure conditions. However, the main cause of the instability of the molten pool and keyhole has not been clarified. It is considered that the interaction between the laser and plume might cause these instabilities. Therefore, in this study, we focused on the plume generated by laser irradiation. The dynamics of the plume during laser welding and the attenuation of the laser were observed under different ambient pressures. According to these observations, the effect of the plume on instability in laser welding was elucidated. The SS304 was fixed in the vacuum chamber, and the disk laser with an output power of 6 kW swept on the sample to form the weld bead. At the same time, the plume behavior was observed by the Schlieren method, and the attenuation of the laser was measured using a probe laser. As a result, the metal vapor jet, which is a periodical plume ejection, was observed. The attenuation of the probe laser increased with increasing atmospheric pressure. These results suggest that the frequent generation of the metal vapor jet under atmospheric pressure caused instability in the heat input of the laser, which caused instability in the keyhole and molten pool.
{"title":"Influence of the laser-induced plume on welding behavior in keyhole welding for stainless steel using a 16 kW disk laser","authors":"Yoshiaki Kurita, Yuji Sato, Shumpei Fujio, Masami Mizutani, Masahiro Tsukamoto","doi":"10.2351/7.0001173","DOIUrl":"https://doi.org/10.2351/7.0001173","url":null,"abstract":"The spatter is one of the defect factors for laser welding. For high-quality laser welding, the elucidation of the spatter reduction mechanism is required. In our previous study, it was elucidated that the molten pool and keyhole fluctuation contribute to spatter generation from the observation of the keyhole and molten pool under different ambient pressure conditions. However, the main cause of the instability of the molten pool and keyhole has not been clarified. It is considered that the interaction between the laser and plume might cause these instabilities. Therefore, in this study, we focused on the plume generated by laser irradiation. The dynamics of the plume during laser welding and the attenuation of the laser were observed under different ambient pressures. According to these observations, the effect of the plume on instability in laser welding was elucidated. The SS304 was fixed in the vacuum chamber, and the disk laser with an output power of 6 kW swept on the sample to form the weld bead. At the same time, the plume behavior was observed by the Schlieren method, and the attenuation of the laser was measured using a probe laser. As a result, the metal vapor jet, which is a periodical plume ejection, was observed. The attenuation of the probe laser increased with increasing atmospheric pressure. These results suggest that the frequent generation of the metal vapor jet under atmospheric pressure caused instability in the heat input of the laser, which caused instability in the keyhole and molten pool.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135739279","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}
Ziang Chen, Ruoyu Zhai, Yuyao Cai, Yanpeng Ye, Zhongmou Sun, Yuzhu Liu
Paper is a widely used material and common recyclable household waste in waste disposal, which gets more attention nowadays for the misclassification of recyclable waste. In this work, an online source tracing system combined with machine learning algorithms to identify and classify the smoke of waste paper incineration based on laser-induced breakdown spectroscopy (LIBS) was established. Four types of waste paper, including tissue, corrugated paper, printing paper, and newspaper, were taken as examples. The smoke of four different waste papers was detected by LIBS and then further analyzed. The detected spectra with C, N, O, Mg, Al, and Ca could hardly be distinguished artificially. The random forest algorithm and the linear discriminant analysis were introduced to classify the smoke, and its accuracy reached 95.83%. The results indicate that source tracing of waste paper can be realized by identifying and classifying the smoke via the developed system. This could provide some reference for helping us to monitor the effectiveness of waste classification and incineration and monitor the atmosphere pollution.
{"title":"Online source tracing of waste paper by smoke based on laser-induced breakdown spectroscopy","authors":"Ziang Chen, Ruoyu Zhai, Yuyao Cai, Yanpeng Ye, Zhongmou Sun, Yuzhu Liu","doi":"10.2351/7.0001226","DOIUrl":"https://doi.org/10.2351/7.0001226","url":null,"abstract":"Paper is a widely used material and common recyclable household waste in waste disposal, which gets more attention nowadays for the misclassification of recyclable waste. In this work, an online source tracing system combined with machine learning algorithms to identify and classify the smoke of waste paper incineration based on laser-induced breakdown spectroscopy (LIBS) was established. Four types of waste paper, including tissue, corrugated paper, printing paper, and newspaper, were taken as examples. The smoke of four different waste papers was detected by LIBS and then further analyzed. The detected spectra with C, N, O, Mg, Al, and Ca could hardly be distinguished artificially. The random forest algorithm and the linear discriminant analysis were introduced to classify the smoke, and its accuracy reached 95.83%. The results indicate that source tracing of waste paper can be realized by identifying and classifying the smoke via the developed system. This could provide some reference for helping us to monitor the effectiveness of waste classification and incineration and monitor the atmosphere pollution.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135738542","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}
Leonardo Caprio, Barbara Previtali, Ali Gökhan Demir
Laser welding is a key enabling technology that transitions toward electric mobility, producing joints with elevated electrical and mechanical properties. In the production of battery packs, cells to busbar connections are challenging due to strict tolerances and zero-fault policy. Hence, it is of great interest to investigate how beam shaping techniques may be exploited to enhance the electromechanical properties as well as to improve material processability. Industrial laser systems often provide the possibility to oscillate dynamically the beam or redistribute the power in multicore fibers. Although contemporary equipment enables elevated flexibility in terms of power redistribution, further studies are required to indicate the most adequate solution for the production of high performance batteries. Within the present investigation, both in-source beam shaping and beam oscillation techniques have been exploited to perform 0.2–0.2 mm Ni-plated steel welds in lap joint configuration, representative of typical cell to busbar connections. An experimental campaign allowed us to define process feasibility conditions where partial penetration welds could be achieved by means of in-source beam shaping. Hence, beam oscillation was explored to perform the connections. In the subset of feasible conditions, the mechanical strength was determined via tensile tests alongside electrical resistance measurements. Linear welds with a Gaussian beam profile enabled joints with the highest productivity at constant electromechanical properties. Spatter formation due to keyhole instabilities could be avoided by redistributing the emission power via multicore fibers, while dynamic oscillation did not provide significant benefits.
{"title":"Effect of in-source beam shaping and laser beam oscillation on the electromechanical properties of Ni-plated steel joints for e-vehicle battery manufacturing","authors":"Leonardo Caprio, Barbara Previtali, Ali Gökhan Demir","doi":"10.2351/7.0001151","DOIUrl":"https://doi.org/10.2351/7.0001151","url":null,"abstract":"Laser welding is a key enabling technology that transitions toward electric mobility, producing joints with elevated electrical and mechanical properties. In the production of battery packs, cells to busbar connections are challenging due to strict tolerances and zero-fault policy. Hence, it is of great interest to investigate how beam shaping techniques may be exploited to enhance the electromechanical properties as well as to improve material processability. Industrial laser systems often provide the possibility to oscillate dynamically the beam or redistribute the power in multicore fibers. Although contemporary equipment enables elevated flexibility in terms of power redistribution, further studies are required to indicate the most adequate solution for the production of high performance batteries. Within the present investigation, both in-source beam shaping and beam oscillation techniques have been exploited to perform 0.2–0.2 mm Ni-plated steel welds in lap joint configuration, representative of typical cell to busbar connections. An experimental campaign allowed us to define process feasibility conditions where partial penetration welds could be achieved by means of in-source beam shaping. Hence, beam oscillation was explored to perform the connections. In the subset of feasible conditions, the mechanical strength was determined via tensile tests alongside electrical resistance measurements. Linear welds with a Gaussian beam profile enabled joints with the highest productivity at constant electromechanical properties. Spatter formation due to keyhole instabilities could be avoided by redistributing the emission power via multicore fibers, while dynamic oscillation did not provide significant benefits.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135790421","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}
The capability to produce complexly and individually shaped metallic parts is one of the main advantages of the laser powder bed fusion process. Development of material and machine specific process parameters is commonly based on the results acquired from small cubic test coupons of ∼10 mm edge length. Such cubes are usually used to conduct the optimization of process parameters to produce dense materials. The parameters are then taken as the basis for the manufacturing of real part geometries. However, complex geometries go along with complex thermal histories during the manufacturing process, which can significantly differ from thermal conditions prevalent during the production of simply shaped test coupons. This may lead to unexpected and unpredicted local inhomogeneities of the microstructure and defect distribution in the final part, and it is a root cause of reservations against the use of additive manufacturing for the production of safety relevant parts. In this study, the influence of changing thermal conditions on the resulting melt pool depth of 316L stainless steel specimens is demonstrated. A variation in thermographically measured intrinsic preheating temperatures was triggered by the alteration of interlayer times and a variation in cross-sectional areas of specimens for three distinct sets of process parameters. Correlations between the preheating temperature, the melt pool depth, and occurring defects were analyzed. The limited expressiveness of the results of small density cubes is revealed throughout the systematic investigation. Finally, a clear recommendation to consider thermal conditions in future process parameter optimizations is given.
{"title":"On the limitations of small cubes as test coupons for process parameter optimization in laser powder bed fusion of metals","authors":"Gunther Mohr, Simon J. Altenburg, Kai Hilgenberg","doi":"10.2351/7.0001080","DOIUrl":"https://doi.org/10.2351/7.0001080","url":null,"abstract":"The capability to produce complexly and individually shaped metallic parts is one of the main advantages of the laser powder bed fusion process. Development of material and machine specific process parameters is commonly based on the results acquired from small cubic test coupons of ∼10 mm edge length. Such cubes are usually used to conduct the optimization of process parameters to produce dense materials. The parameters are then taken as the basis for the manufacturing of real part geometries. However, complex geometries go along with complex thermal histories during the manufacturing process, which can significantly differ from thermal conditions prevalent during the production of simply shaped test coupons. This may lead to unexpected and unpredicted local inhomogeneities of the microstructure and defect distribution in the final part, and it is a root cause of reservations against the use of additive manufacturing for the production of safety relevant parts. In this study, the influence of changing thermal conditions on the resulting melt pool depth of 316L stainless steel specimens is demonstrated. A variation in thermographically measured intrinsic preheating temperatures was triggered by the alteration of interlayer times and a variation in cross-sectional areas of specimens for three distinct sets of process parameters. Correlations between the preheating temperature, the melt pool depth, and occurring defects were analyzed. The limited expressiveness of the results of small density cubes is revealed throughout the systematic investigation. Finally, a clear recommendation to consider thermal conditions in future process parameter optimizations is given.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-10-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135830185","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}
S. Stoyanov, D. Petring, F. Piedboeuf, M. Lopes, F. Schneider
During laser fusion cutting, burr forms when the molten metal does not sufficiently exit the interaction zone. When it forms on the lower edge of the cut flank, burr becomes a factor limiting quality. Previous research has shown that a temporally regular and spatially localized melt flow can prevent the formation of burr. However, the high dynamics of the subprocesses involved can cause intrinsic instabilities that disrupt the flow and reduce the efficiency of the melt ejection. This paper presents a study on the correlation between process parameters, melt flow properties, and burr formation. It includes an experimental observation of the melt-flow dynamics using high-speed videography. In addition, a Computational Fluid Dynamics model was set up to examine fundamental flow properties, some of which are not observable experimentally. The dependency of the burr formation on the liquid Weber and Reynolds numbers is analyzed, and it is demonstrated how the magnitude and allocation of vapor pressure gradients in the kerf decisively affect melt ejection and burr formation. Additionally, a previously unknown melt ejection regime is identified in the thick section range, which occurs at feed rates close to the maximum cutting speed under specific high-power process conditions. This regime is characterized by a significantly increased process efficiency that could open up a new high-speed process window.
{"title":"Numerical and experimental investigation of the melt removal mechanism and burr formation during laser cutting of metals","authors":"S. Stoyanov, D. Petring, F. Piedboeuf, M. Lopes, F. Schneider","doi":"10.2351/7.0001182","DOIUrl":"https://doi.org/10.2351/7.0001182","url":null,"abstract":"During laser fusion cutting, burr forms when the molten metal does not sufficiently exit the interaction zone. When it forms on the lower edge of the cut flank, burr becomes a factor limiting quality. Previous research has shown that a temporally regular and spatially localized melt flow can prevent the formation of burr. However, the high dynamics of the subprocesses involved can cause intrinsic instabilities that disrupt the flow and reduce the efficiency of the melt ejection. This paper presents a study on the correlation between process parameters, melt flow properties, and burr formation. It includes an experimental observation of the melt-flow dynamics using high-speed videography. In addition, a Computational Fluid Dynamics model was set up to examine fundamental flow properties, some of which are not observable experimentally. The dependency of the burr formation on the liquid Weber and Reynolds numbers is analyzed, and it is demonstrated how the magnitude and allocation of vapor pressure gradients in the kerf decisively affect melt ejection and burr formation. Additionally, a previously unknown melt ejection regime is identified in the thick section range, which occurs at feed rates close to the maximum cutting speed under specific high-power process conditions. This regime is characterized by a significantly increased process efficiency that could open up a new high-speed process window.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135199206","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}
Michael Desens, Katharina Rettschlag, Peter Jäschke, Stefan Kaierle
Welding of quartz glass is still mainly carried out with gas torches and manually by glass specialists. The use of gas torches is highly energy inefficient as much heat energy is released around the component and into the environment. In addition, the manual process can result in inhomogeneous welds. An automated laser process would make quartz glass welding more energy-efficient and repeatable and address the growing shortage of skilled labor. In this study, quartz glass plates up to 4.5 mm in thickness are welded together at an angle of 125° to each other using a fiber or rod as the filler material. Glass thickness and angle were selected based on a project-specific application. The aim is to achieve a homogeneous weld with as few defects as possible using a lateral fiber- or rod-based deposition welding process. The main challenge is to achieve the melting of the filler material at the bottom contact point of the two glasses so that no air inclusions occur. A 400 μm fiber and a 1 mm rod are investigated as filler materials. The advantage of the fiber compared to the rod is that the contact point of the glasses is easier to reach and bond during the welding process. Due to the large gap between the glass fibers compared to the fiber diameter, a high fiber feed rate is required to fill the V-gap with the viscous glass material. The disadvantage is that the fiber is subjected to high pressure when digging into the melt, which can lead to fiber breakage. In addition, there is a high consumption of filling material. Adjustable and relevant process parameters include the ratio between substrate and fiber feed, the laser power, the spot diameter, and the process gas pressure. The fabricated samples are analyzed using optical and laser confocal microscopy.
{"title":"Using fiber or rod—The influence of different filler materials during CO2 laser welding of quartz glass","authors":"Michael Desens, Katharina Rettschlag, Peter Jäschke, Stefan Kaierle","doi":"10.2351/7.0001120","DOIUrl":"https://doi.org/10.2351/7.0001120","url":null,"abstract":"Welding of quartz glass is still mainly carried out with gas torches and manually by glass specialists. The use of gas torches is highly energy inefficient as much heat energy is released around the component and into the environment. In addition, the manual process can result in inhomogeneous welds. An automated laser process would make quartz glass welding more energy-efficient and repeatable and address the growing shortage of skilled labor. In this study, quartz glass plates up to 4.5 mm in thickness are welded together at an angle of 125° to each other using a fiber or rod as the filler material. Glass thickness and angle were selected based on a project-specific application. The aim is to achieve a homogeneous weld with as few defects as possible using a lateral fiber- or rod-based deposition welding process. The main challenge is to achieve the melting of the filler material at the bottom contact point of the two glasses so that no air inclusions occur. A 400 μm fiber and a 1 mm rod are investigated as filler materials. The advantage of the fiber compared to the rod is that the contact point of the glasses is easier to reach and bond during the welding process. Due to the large gap between the glass fibers compared to the fiber diameter, a high fiber feed rate is required to fill the V-gap with the viscous glass material. The disadvantage is that the fiber is subjected to high pressure when digging into the melt, which can lead to fiber breakage. In addition, there is a high consumption of filling material. Adjustable and relevant process parameters include the ratio between substrate and fiber feed, the laser power, the spot diameter, and the process gas pressure. The fabricated samples are analyzed using optical and laser confocal microscopy.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135386899","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}
Cledenir Costa de Oliveira, Milton Pereira, Claudio Abilio da Silveira, Manoel Kolling Dutra, Calil Amaral
This study examines the impact of wobble movement on a laser beam’s behavior while moving over an AISI 316L stainless steel sample of 1.2 mm thickness during welding. The laser beam oscillatory movement is superimposed on linear movement, using a 400 W fiber laser installed on an experimental bench equipped with a scanner and worktable. Mathematical modeling estimates instantaneous beam speed values, predicting thermal influence on weld bead aspects. Microwelding experiments use autogenous processing with lateral beam oscillation. Two forms of overlapping transverse wobble are tested: one with a circular path and the other describing the mathematical symbol “infinity.” Correlations are evidenced between the input parameters and results obtained in the microwelds, including penetration and width of the beads. Results show that the frequency of movement in a circle and in “infinity” for frequencies from 200 to 400 Hz has no significant influence on the result. Increasing the amplitude of the wobble movement from 0.5 to 2 mm significantly influences the width and depth of the strands generated. The wobble technique is effective in preventing discontinuities in the process, such as porosities. A bead obtained with 300 W, 50 mm/s, 0.5 mm overlapping wobble movement, and 300 Hz circular rotation frequency showed the highest relationship between width and depth.
{"title":"Effect of wobble parameters on microwelding bead formation of AISI 316L stainless steel","authors":"Cledenir Costa de Oliveira, Milton Pereira, Claudio Abilio da Silveira, Manoel Kolling Dutra, Calil Amaral","doi":"10.2351/7.0001123","DOIUrl":"https://doi.org/10.2351/7.0001123","url":null,"abstract":"This study examines the impact of wobble movement on a laser beam’s behavior while moving over an AISI 316L stainless steel sample of 1.2 mm thickness during welding. The laser beam oscillatory movement is superimposed on linear movement, using a 400 W fiber laser installed on an experimental bench equipped with a scanner and worktable. Mathematical modeling estimates instantaneous beam speed values, predicting thermal influence on weld bead aspects. Microwelding experiments use autogenous processing with lateral beam oscillation. Two forms of overlapping transverse wobble are tested: one with a circular path and the other describing the mathematical symbol “infinity.” Correlations are evidenced between the input parameters and results obtained in the microwelds, including penetration and width of the beads. Results show that the frequency of movement in a circle and in “infinity” for frequencies from 200 to 400 Hz has no significant influence on the result. Increasing the amplitude of the wobble movement from 0.5 to 2 mm significantly influences the width and depth of the strands generated. The wobble technique is effective in preventing discontinuities in the process, such as porosities. A bead obtained with 300 W, 50 mm/s, 0.5 mm overlapping wobble movement, and 300 Hz circular rotation frequency showed the highest relationship between width and depth.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135536461","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}
Jacob J. Lavin, Jay J. Robus, Toby Williams, Edward J. Long, John R. Tyrer, Julian T. Spencer, Jonathan M. Dodds, Lewis C. R. Jones
High gas pressures (1.0–1.6 MPa) are employed in conventional inert laser cutting to achieve efficient material removal and high cut quality. However, this approach results in the emission of large quantities of by-products, which can pose a risk to human health and the environment. For applications such as nuclear decommissioning, where global extraction and containment can be challenging, hazardous by-product formation, rather than process efficiency, is the main priority. This paper demonstrates low-pressure (0.3–0.6 MPa) laser-cutting techniques developed to reduce by-products. This study investigates the causal links between melt ejection and gas dynamic interactions in low-pressure laser cutting. Experiments were conducted using a 300 W Nd:Yb fiber laser to cut 304 stainless steel samples. Melt ejection and breakdown profiles were captured using a FASTCAM mini AX 200 camera. The lens combination fitted to the camera provided a spatial resolution of approximately 1 μm. The gas dynamic interactions were assessed through comparisons with existing studies of Schlieren imaging in idealized environments. The results show that gas dynamics are crucial in melt ejection and breakdown mechanisms during laser cutting. The key findings of this study are images of breakdown mechanisms linked to low-pressure gas dynamics. The impact of this work is that breakdown mechanisms more favorable to reducing environmental risk have been demonstrated. A greater understanding of the risk is indispensable to developing new laser-cutting control methods for hazardous materials.
传统惰性激光切割采用高压(1.0-1.6 MPa)，可实现高效的材料去除和高切割质量。然而，这种做法导致大量副产品的排放，可能对人类健康和环境构成风险。对于诸如核退役之类的应用，在这些应用中，全球提取和密封可能具有挑战性，因此主要优先考虑的是危险副产品的形成，而不是过程效率。本文介绍了为减少副产物而开发的低压(0.3-0.6 MPa)激光切割技术。本文研究了低压激光切割中熔体喷射与气体动力学相互作用之间的因果关系。利用300 W Nd:Yb光纤激光器对304不锈钢试样进行了切割实验。使用FASTCAM mini AX 200相机捕捉熔体喷射和击穿轮廓。安装在相机上的镜头组合提供了约1 μm的空间分辨率。通过与现有的理想环境下纹影成像研究进行比较，评估了气体动力学相互作用。结果表明，气体动力学在激光切割过程中熔体喷射和击穿机理中起着至关重要的作用。这项研究的主要发现是与低压气体动力学有关的分解机制的图像。这项工作的影响是，更有利于减少环境风险的分解机制已被证明。对危险材料的激光切割控制方法的进一步了解是开发新的激光切割控制方法必不可少的。
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