Jan Marx, Nikolas Arthkamp, C. Esen, Andreas Ostendorf
In times of digitalization, multilayer composite materials became central components in an increasing number of application fields. Thus, there is a need for optimization of the cost-intensive and time-consuming processing of multilayer composites. In this contribution, an ultrashort pulse laser-based method is presented for precise and flexible ablation of a printed circuit board base material. Therefore, an 800 nm Gaussian laser beam was transformed into a Bessel beam by an axicon to get a small spot size and an ablation result with a high aspect ratio. The influence of the average laser power, the number of exposure cycles, and the pulse duration on the geometry as well as the surface quality of ablated structures was investigated and compared to Gaussian beam ablation. Furthermore, it is shown that the results can be transferred to microdrilling processes. With the presented method, it was possible to ablate the copper top layer of the printed circuit boards as well as the FR4 layer below with a precisely adjustable depth.
{"title":"Ultrashort pulse ablation of printed circuit board materials using a Bessel beam","authors":"Jan Marx, Nikolas Arthkamp, C. Esen, Andreas Ostendorf","doi":"10.2351/7.0001170","DOIUrl":"https://doi.org/10.2351/7.0001170","url":null,"abstract":"In times of digitalization, multilayer composite materials became central components in an increasing number of application fields. Thus, there is a need for optimization of the cost-intensive and time-consuming processing of multilayer composites. In this contribution, an ultrashort pulse laser-based method is presented for precise and flexible ablation of a printed circuit board base material. Therefore, an 800 nm Gaussian laser beam was transformed into a Bessel beam by an axicon to get a small spot size and an ablation result with a high aspect ratio. The influence of the average laser power, the number of exposure cycles, and the pulse duration on the geometry as well as the surface quality of ablated structures was investigated and compared to Gaussian beam ablation. Furthermore, it is shown that the results can be transferred to microdrilling processes. With the presented method, it was possible to ablate the copper top layer of the printed circuit boards as well as the FR4 layer below with a precisely adjustable depth.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-12-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139008224","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}
J. Kohl, Thomas Will, Tobias Klier, Lars Müller, Christian Goth
Glass-filled composites are used for overmolding of electrical components due to their good electrical isolation properties. Laser cutting is a preferred technology to remove excess mold material to achieve a low surface roughness and reduce tool wear. Hatching strategies improve the laser-cutting process of carbon fiber-reinforced polymers toward lower cutting times and a more homogeneous cut surface. The impact of hatching strategies on epoxy mold compounds has been so far unknown as the laser-cutting strategy was based on multiple single passes in previous studies. This work investigates the effects of hatching strategies such as perpendicular hatching, parallel hatching, and a single line, including the influence of material thickness and filler content regarding the cutting time, kerf taper angle, and heat-affected zone, using a 50 W short-pulsed fiber laser for different highly filled epoxy mold compounds. Results show that the use of a hatching strategy is required to cut workpieces at thicknesses of 4 mm or higher due to the sieving size of the filler. Perpendicular hatching needs to be chosen when the aim is a minimal cutting time. The kerf taper angle at the top of the cut is below 4° while hatching leads to a more pronounced kink of up to 25° occurring toward the bottom of the cut. Meanwhile, an increase in filler concentration leads to an increase in cutting time, because of higher thermal conduction, while no effect on the kerf taper angle or the heat-affected zone can be identified.
玻璃填充复合材料具有良好的电气绝缘性能，可用于电气元件的包覆成型。激光切割是去除多余模具材料的首选技术，可实现较低的表面粗糙度并减少工具磨损。孵化策略改进了碳纤维增强聚合物的激光切割工艺，从而缩短了切割时间，并使切割表面更加均匀。在以往的研究中，由于激光切割策略是基于多次单程切割，因此迄今为止还不知道孵化策略对环氧树脂模具化合物的影响。本研究使用 50 W 短脉冲光纤激光器，针对不同的高填充环氧树脂模具化合物，研究了垂直蚀刻、平行蚀刻和单线等蚀刻策略的效果，包括材料厚度和填充物含量对切割时间、切口锥角和热影响区的影响。结果表明，由于填料的筛分尺寸，在切割厚度为 4 毫米或更厚的工件时需要使用分切策略。如果要尽量缩短切割时间，则需要选择垂直切口。切口顶部的切口锥角低于 4°，而刻纹会导致切口底部出现更明显的锥角，最大可达 25°。同时，由于热传导更高，填料浓度的增加会导致切割时间的增加，而对切口锥角或热影响区没有影响。
{"title":"Influence of material thickness and hatching strategies on laser cutting of epoxy mold composites","authors":"J. Kohl, Thomas Will, Tobias Klier, Lars Müller, Christian Goth","doi":"10.2351/7.0001137","DOIUrl":"https://doi.org/10.2351/7.0001137","url":null,"abstract":"Glass-filled composites are used for overmolding of electrical components due to their good electrical isolation properties. Laser cutting is a preferred technology to remove excess mold material to achieve a low surface roughness and reduce tool wear. Hatching strategies improve the laser-cutting process of carbon fiber-reinforced polymers toward lower cutting times and a more homogeneous cut surface. The impact of hatching strategies on epoxy mold compounds has been so far unknown as the laser-cutting strategy was based on multiple single passes in previous studies. This work investigates the effects of hatching strategies such as perpendicular hatching, parallel hatching, and a single line, including the influence of material thickness and filler content regarding the cutting time, kerf taper angle, and heat-affected zone, using a 50 W short-pulsed fiber laser for different highly filled epoxy mold compounds. Results show that the use of a hatching strategy is required to cut workpieces at thicknesses of 4 mm or higher due to the sieving size of the filler. Perpendicular hatching needs to be chosen when the aim is a minimal cutting time. The kerf taper angle at the top of the cut is below 4° while hatching leads to a more pronounced kink of up to 25° occurring toward the bottom of the cut. Meanwhile, an increase in filler concentration leads to an increase in cutting time, because of higher thermal conduction, while no effect on the kerf taper angle or the heat-affected zone can be identified.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139010595","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 the case of “hidden” T-joints, the nonvisible web sheet is welded through the face sheet. Positioning tolerances and movement due to the distortion of the web sheet represent the main challenges to maintain on track during laser beam welding. This study investigated the assumption that keyhole monitoring based on optical coherence tomography (OCT) could be utilized for seam tracking by detecting critical misalignments between the laser beam and the web sheet position. It hereby analyzed whether an emerging misalignment between the laser beam and the web sheet could be discerned in the OCT data before the laser beam misses the web sheet and penetrated only the face sheet. This prediction represents a key requirement for the industrial use of this approach. To this end, this study investigated the welding of hidden T-joints with angular and parallel offsets of the laser path relative to the web sheet centerline while recording with OCT. The interface zone between the web and face sheets was recorded by a high-speed camera to detect the transmission of laser radiation through a lower keyhole opening. It was shown that a lower keyhole opening, in combination with transmitted radiation, was advantageous for the reliable detection of an emerging misalignment. This lower keyhole opening can occur lateral to the web sheet prior to a misalignment, therefore enabling a prediction of spot misalignments via OCT. The welding parameter dependent maximum distance of the laser spot edge to the web sheet edge at detection was 0.1 mm in this study.
{"title":"Understanding the coaxial optical coherence tomography signal during the laser welding of hidden T-joints","authors":"T. Mattulat","doi":"10.2351/7.0001157","DOIUrl":"https://doi.org/10.2351/7.0001157","url":null,"abstract":"In the case of “hidden” T-joints, the nonvisible web sheet is welded through the face sheet. Positioning tolerances and movement due to the distortion of the web sheet represent the main challenges to maintain on track during laser beam welding. This study investigated the assumption that keyhole monitoring based on optical coherence tomography (OCT) could be utilized for seam tracking by detecting critical misalignments between the laser beam and the web sheet position. It hereby analyzed whether an emerging misalignment between the laser beam and the web sheet could be discerned in the OCT data before the laser beam misses the web sheet and penetrated only the face sheet. This prediction represents a key requirement for the industrial use of this approach. To this end, this study investigated the welding of hidden T-joints with angular and parallel offsets of the laser path relative to the web sheet centerline while recording with OCT. The interface zone between the web and face sheets was recorded by a high-speed camera to detect the transmission of laser radiation through a lower keyhole opening. It was shown that a lower keyhole opening, in combination with transmitted radiation, was advantageous for the reliable detection of an emerging misalignment. This lower keyhole opening can occur lateral to the web sheet prior to a misalignment, therefore enabling a prediction of spot misalignments via OCT. The welding parameter dependent maximum distance of the laser spot edge to the web sheet edge at detection was 0.1 mm in this study.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138598262","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}
An acoustic signal acquisition experiment platform was constructed to gather the acoustic signals throughout the formation of 35 single-tracks of a 120 mm length copper-tin alloy in order to monitor and precisely manage the selective laser melting (SLM) forming process and enhance overall quality. The monitoring of the SLM forming process includes the analysis of the time and frequency domains, the extraction of the SLM process features using linear prediction techniques, and the development of support vector machine (SVM) model, back-propagation (BP) neural network models, and convolutional neural network models. The results show that the over-melted state can be identified by extracting time and frequency-domain features over a given range, but the normal and unmelted states are difficult to distinguish. The convolutional neural network model had a recognition rate of 99%, the BP neural network had an effective recognition rate of 90%, and the SVM model had a combined classification rate of 83.14% for the three states after optimization. In contrast, the convolutional neural network model performs best in monitoring and offers a framework and point of reference for acoustic signal analysis and online SLM quality monitoring.
{"title":"Research of melting state identification and process performance based on selective laser melting acoustic signals","authors":"Dongju Chen, Anqing Wang, Peng Wang, Na Li","doi":"10.2351/7.0000991","DOIUrl":"https://doi.org/10.2351/7.0000991","url":null,"abstract":"An acoustic signal acquisition experiment platform was constructed to gather the acoustic signals throughout the formation of 35 single-tracks of a 120 mm length copper-tin alloy in order to monitor and precisely manage the selective laser melting (SLM) forming process and enhance overall quality. The monitoring of the SLM forming process includes the analysis of the time and frequency domains, the extraction of the SLM process features using linear prediction techniques, and the development of support vector machine (SVM) model, back-propagation (BP) neural network models, and convolutional neural network models. The results show that the over-melted state can be identified by extracting time and frequency-domain features over a given range, but the normal and unmelted states are difficult to distinguish. The convolutional neural network model had a recognition rate of 99%, the BP neural network had an effective recognition rate of 90%, and the SVM model had a combined classification rate of 83.14% for the three states after optimization. In contrast, the convolutional neural network model performs best in monitoring and offers a framework and point of reference for acoustic signal analysis and online SLM quality monitoring.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-12-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138598700","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}
Santiago Caraguay, Thiago Soares Pereira, Francisco Ratuznei, Miriam Zareth Parra Sejas, Milton Pereira, Fabio Antônio Xavier
Surface tortuosity is a quantitative measure of the complexity of a material's surface. It is commonly defined as the ratio between the real length of the surface over the shortest distance between two points on the surface. An increase in surface tortuosity has been found to have advantageous effects on the durability of coated parts when exposed to corrosive and humid conditions. Laser surface texturing, a versatile process, can be used to modify the surface tortuosity by creating various structure patterns on the surface of steel. This study aims to investigate the impact of V-shaped groove dimensions on the resistance against corrosion creep of an organic coating applied to textured surfaces. Comparative surface tortuosity measurements were obtained for different groove dimensions while keeping the aspect ratio and textured areas constant. V-shaped grooves with an aspect ratio of 1 and sizes of 50, 100, and 200 μm were machined on carbon steel AISI-A36. The distance between adjacent grooves was varied to achieve different textured areas, ranging from 10% to 60%. The surface roughness (Sa) and surface tortuosity were characterized. The performance of the coating was evaluated using an accelerated corrosion test based on ISO 12944-9. The results indicate that V-shaped grooves with dimensions of 100 μm and a textured area of 40% exhibit the lowest coating delamination. It is worth to mention that the performance of organic coatings is enhanced up to a certain optimal point by an increase in surface tortuosity. However, beyond this optimal point, further increases in tortuosity do not lead to an increased resistance to the propagation of corrosion.
{"title":"Evaluation of surface tortuosity on the corrosion resistance of organic coatings using laser texturing process","authors":"Santiago Caraguay, Thiago Soares Pereira, Francisco Ratuznei, Miriam Zareth Parra Sejas, Milton Pereira, Fabio Antônio Xavier","doi":"10.2351/7.0001107","DOIUrl":"https://doi.org/10.2351/7.0001107","url":null,"abstract":"Surface tortuosity is a quantitative measure of the complexity of a material's surface. It is commonly defined as the ratio between the real length of the surface over the shortest distance between two points on the surface. An increase in surface tortuosity has been found to have advantageous effects on the durability of coated parts when exposed to corrosive and humid conditions. Laser surface texturing, a versatile process, can be used to modify the surface tortuosity by creating various structure patterns on the surface of steel. This study aims to investigate the impact of V-shaped groove dimensions on the resistance against corrosion creep of an organic coating applied to textured surfaces. Comparative surface tortuosity measurements were obtained for different groove dimensions while keeping the aspect ratio and textured areas constant. V-shaped grooves with an aspect ratio of 1 and sizes of 50, 100, and 200 μm were machined on carbon steel AISI-A36. The distance between adjacent grooves was varied to achieve different textured areas, ranging from 10% to 60%. The surface roughness (Sa) and surface tortuosity were characterized. The performance of the coating was evaluated using an accelerated corrosion test based on ISO 12944-9. The results indicate that V-shaped grooves with dimensions of 100 μm and a textured area of 40% exhibit the lowest coating delamination. It is worth to mention that the performance of organic coatings is enhanced up to a certain optimal point by an increase in surface tortuosity. However, beyond this optimal point, further increases in tortuosity do not lead to an increased resistance to the propagation of corrosion.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-12-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138603143","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. Gruber, L. Stepien, L. Gerdt, E. López, Jan Kieser, F. Brueckner, Christoph Leyens, Craig Bratt
Copper is widely used in high heat flux and electrical applications because of its excellent electrical and thermal conductivity properties. Alloying elements such as chromium or nickel are added to strengthen the material, especially for higher temperatures. Cu4Cr2Nb, also known as GRCop-42, is a dispersion-strengthened copper-chromium-niobium alloy developed by NASA for high-temperature applications with high thermal and mechanical stresses such as rocket engines. Additive manufacturing (AM) enables applications with complex functionalized geometries and is particularly promising in the aerospace industry. In this contribution, a parametric study was performed for GRCop-42 and the AM process laser powder bed fusion (PBF-LB/M) using a green laser source for two-layer thicknesses of 30 and 60 μm. Density, electrical conductivity, hardness, microstructure, and static mechanical properties were analyzed. Various heat treatments ranging from 400 to 1000 °C and 30 min to 4 h were tested to increase the electrical conductivity and hardness. For both layer thicknesses, dense parameter sets could be obtained with resulting relative densities above 99.8%. Hardness and electrical conductivity could be tailored in the range of 103–219 HV2 and 24%–88% International Annealed Copper Standard (IACS) depending on the heat treatment. The highest ultimate tensile strength (UTS) obtained was 493 MPa. An aging temperature of 700 °C for 30 min showed the best combination of room temperature properties such as electrical conductivity of 83.76%IACS, UTS of 481 MPa, elongation at break (A) at 24%, and hardness of 125 HV2.
{"title":"Process development for laser powder bed fusion of GRCop-42 using a 515 nm laser source","authors":"S. Gruber, L. Stepien, L. Gerdt, E. López, Jan Kieser, F. Brueckner, Christoph Leyens, Craig Bratt","doi":"10.2351/7.0001139","DOIUrl":"https://doi.org/10.2351/7.0001139","url":null,"abstract":"Copper is widely used in high heat flux and electrical applications because of its excellent electrical and thermal conductivity properties. Alloying elements such as chromium or nickel are added to strengthen the material, especially for higher temperatures. Cu4Cr2Nb, also known as GRCop-42, is a dispersion-strengthened copper-chromium-niobium alloy developed by NASA for high-temperature applications with high thermal and mechanical stresses such as rocket engines. Additive manufacturing (AM) enables applications with complex functionalized geometries and is particularly promising in the aerospace industry. In this contribution, a parametric study was performed for GRCop-42 and the AM process laser powder bed fusion (PBF-LB/M) using a green laser source for two-layer thicknesses of 30 and 60 μm. Density, electrical conductivity, hardness, microstructure, and static mechanical properties were analyzed. Various heat treatments ranging from 400 to 1000 °C and 30 min to 4 h were tested to increase the electrical conductivity and hardness. For both layer thicknesses, dense parameter sets could be obtained with resulting relative densities above 99.8%. Hardness and electrical conductivity could be tailored in the range of 103–219 HV2 and 24%–88% International Annealed Copper Standard (IACS) depending on the heat treatment. The highest ultimate tensile strength (UTS) obtained was 493 MPa. An aging temperature of 700 °C for 30 min showed the best combination of room temperature properties such as electrical conductivity of 83.76%IACS, UTS of 481 MPa, elongation at break (A) at 24%, and hardness of 125 HV2.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139305331","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 aerospace, thermal applications demand compact, lightweight, and efficient heat exchangers. Additive manufacturing processes offer the potential to create highly complex structures that are not achievable through traditional manufacturing methods. This work presents the development of an additively manufactured fluid-fluid heat exchanger that shows the potential to enhance the performance, reduce weight, and increase compactness compared to a conventional plate heat exchanger. A numerical model of the conventional plate heat exchanger was created, and fluid dynamics simulations with heat transfer were performed. Validation of the simulations was done by experiments. Then, a novel heat exchanger was designed using a bottom-up approach and investigated at different levels of complexity using computational fluid dynamics. The internal structure of the final heat exchanger consists of a repeating triply periodic Schwarz diamond minimum surface elongated in the direction of flow. The heat exchanger was manufactured with laser powder bed fusion process using AlSi10Mg. It had a 108% higher compactness and 54% lower weight compared to the plate heat exchanger. Numerical analysis yielded the pressure loss in pascal was reduced by 50%–59% while heat transfer in watts was improved by 3%–5%. Future researches should experimentally investigate the thermal and fluid mechanical characteristics of the novel additively manufactured heat exchanger and increase compactness and heat transfer further by analyzing the minimum partition wall thickness and the impact of wall roughness and deposit formation.
{"title":"Design and numerical assessment of an additively manufactured Schwarz diamond triply periodic minimal surface fluid-fluid heat exchanger","authors":"Tim Röver, Maxim Kuehne, Floyd Bischop, Leighton Clague, Bastian Bossen, Claus Emmelmann","doi":"10.2351/7.0001184","DOIUrl":"https://doi.org/10.2351/7.0001184","url":null,"abstract":"In aerospace, thermal applications demand compact, lightweight, and efficient heat exchangers. Additive manufacturing processes offer the potential to create highly complex structures that are not achievable through traditional manufacturing methods. This work presents the development of an additively manufactured fluid-fluid heat exchanger that shows the potential to enhance the performance, reduce weight, and increase compactness compared to a conventional plate heat exchanger. A numerical model of the conventional plate heat exchanger was created, and fluid dynamics simulations with heat transfer were performed. Validation of the simulations was done by experiments. Then, a novel heat exchanger was designed using a bottom-up approach and investigated at different levels of complexity using computational fluid dynamics. The internal structure of the final heat exchanger consists of a repeating triply periodic Schwarz diamond minimum surface elongated in the direction of flow. The heat exchanger was manufactured with laser powder bed fusion process using AlSi10Mg. It had a 108% higher compactness and 54% lower weight compared to the plate heat exchanger. Numerical analysis yielded the pressure loss in pascal was reduced by 50%–59% while heat transfer in watts was improved by 3%–5%. Future researches should experimentally investigate the thermal and fluid mechanical characteristics of the novel additively manufactured heat exchanger and increase compactness and heat transfer further by analyzing the minimum partition wall thickness and the impact of wall roughness and deposit formation.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139292511","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}
Laser cleaning is an advanced cleaning technology which is widely used in the manufacturing industry. Compared with the common planar laser cleaning process, the laser cleaning process of curved surface is difficult to control the completeness and homogeneity of the cleaning layer, which has a great influence on the surface quality and mechanical properties of the cleaned parts. Therefore, a three-dimensional numerical model of the laser cleaning process of the curved surface considering the coordinate system transformation of the heat source is established in this paper to clean the alumina on the surface of the 5754 aluminum alloy. The temperature distribution characteristics for different tangent slopes of the laser cleaning path and the temperature variation with time for different cleaning paths of the laser cleaning process are analyzed. The results show that the proposed method can provide important guiding significance for the practical laser cleaning process of the curved surface.
{"title":"Analysis for temperature distribution of laser cleaning process of curved surface by numerical simulation","authors":"Yuewei Ai, Guangyu Dong, Yachao Yan","doi":"10.2351/7.0001130","DOIUrl":"https://doi.org/10.2351/7.0001130","url":null,"abstract":"Laser cleaning is an advanced cleaning technology which is widely used in the manufacturing industry. Compared with the common planar laser cleaning process, the laser cleaning process of curved surface is difficult to control the completeness and homogeneity of the cleaning layer, which has a great influence on the surface quality and mechanical properties of the cleaned parts. Therefore, a three-dimensional numerical model of the laser cleaning process of the curved surface considering the coordinate system transformation of the heat source is established in this paper to clean the alumina on the surface of the 5754 aluminum alloy. The temperature distribution characteristics for different tangent slopes of the laser cleaning path and the temperature variation with time for different cleaning paths of the laser cleaning process are analyzed. The results show that the proposed method can provide important guiding significance for the practical laser cleaning process of the curved surface.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":2.1,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139303483","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}
Ryan Mullennex, Wuji Huang, Casey Harwood, James Buchholz, Hongtao Ding
Air bubble injection has been a widely studied method for reducing frictional drag in fluid flows, especially in the marine industry. However, the lack of control over air bubble stability, size, and shape has hindered its widespread adoption. This study investigates the use of laser-based surface wettability modification techniques to address these challenges by enhancing control over air bubble behavior in water flows. We processed metal plates using nanosecond laser and chemical immersion to create wettability patterns consisting of regions of either superhydrophobicity or superhydrophilicity. Water tunnel experiments were conducted to observe the behavior of air bubbles over these different wettability patterns. The results revealed that surface wettability can be used to control the size and spatial distribution of air bubbles, which can enhance the energy cost-benefit of drag reduction methods in the marine industry. Moreover, this research offers new insights into the potential of laser-based surface wettability modification as a solution for improving the control of air bubble behavior in large-scale applications.
{"title":"Enhancing control of air bubbles in water flows through laser-based surface wettability patterning","authors":"Ryan Mullennex, Wuji Huang, Casey Harwood, James Buchholz, Hongtao Ding","doi":"10.2351/7.0001142","DOIUrl":"https://doi.org/10.2351/7.0001142","url":null,"abstract":"Air bubble injection has been a widely studied method for reducing frictional drag in fluid flows, especially in the marine industry. However, the lack of control over air bubble stability, size, and shape has hindered its widespread adoption. This study investigates the use of laser-based surface wettability modification techniques to address these challenges by enhancing control over air bubble behavior in water flows. We processed metal plates using nanosecond laser and chemical immersion to create wettability patterns consisting of regions of either superhydrophobicity or superhydrophilicity. Water tunnel experiments were conducted to observe the behavior of air bubbles over these different wettability patterns. The results revealed that surface wettability can be used to control the size and spatial distribution of air bubbles, which can enhance the energy cost-benefit of drag reduction methods in the marine industry. Moreover, this research offers new insights into the potential of laser-based surface wettability modification as a solution for improving the control of air bubble behavior in large-scale applications.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135714459","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}
Jian Cheng, Feng Xie, Yulong Chen, Xingpeng Zhang, Zhongshen Zhai, Fengping Li, Dun Liu
Joining stainless steel to superalloy is currently of extensive interest for applications in aviation and automotive industries. However, conventional welding is prone to encounter defects such as cracks and austenite grain coarsening in the fusion zone. In the present study, laser welding was applied to join SUS304 stainless steel and Inconel718 superalloy circular tubes due to their precise local heat input and accuracy. The effects of defocusing distance, welding speed, and laser power on welding characteristics were studied by changing the values of the mentioned parameters, which manifested that different process parameters exerted a tremendous impact on the cross section morphology and shape of the weld seam. In addition, finite element simulation software was used to simulate temperature field distribution. The results revealed that there would be a buffering region on the temperature field once the laser power gradually decreased, which remarkably reflected the effect of the laser power descending on eliminating weld craters. Therefore, the crater defects caused by laser beam accelerating and decelerating at the start and end of welding could be effectively eliminated through synchronously regulating laser power in the real welding process.
{"title":"Butt welding of SUS304 and Inconel718 tubes by using defocused laser beam","authors":"Jian Cheng, Feng Xie, Yulong Chen, Xingpeng Zhang, Zhongshen Zhai, Fengping Li, Dun Liu","doi":"10.2351/7.0001086","DOIUrl":"https://doi.org/10.2351/7.0001086","url":null,"abstract":"Joining stainless steel to superalloy is currently of extensive interest for applications in aviation and automotive industries. However, conventional welding is prone to encounter defects such as cracks and austenite grain coarsening in the fusion zone. In the present study, laser welding was applied to join SUS304 stainless steel and Inconel718 superalloy circular tubes due to their precise local heat input and accuracy. The effects of defocusing distance, welding speed, and laser power on welding characteristics were studied by changing the values of the mentioned parameters, which manifested that different process parameters exerted a tremendous impact on the cross section morphology and shape of the weld seam. In addition, finite element simulation software was used to simulate temperature field distribution. The results revealed that there would be a buffering region on the temperature field once the laser power gradually decreased, which remarkably reflected the effect of the laser power descending on eliminating weld craters. Therefore, the crater defects caused by laser beam accelerating and decelerating at the start and end of welding could be effectively eliminated through synchronously regulating laser power in the real welding process.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2023-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135714561","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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