Kosei Yamamoto, Ryuhei Matsuda, K. Takenaka, Yuji Sato, Y. Yamashita, Ayahito Saikai, Taisei Yachi, M. Kusaba, Masahiro Tsukamoto
A tungsten carbide–cobalt (WC–Co) composite layer was formed on a stainless-steel type 304 (SS304) substrate using multibeam laser metal deposition (LMD) with blue diode lasers. This paper aims to provide WC–Co layer formation with low porosity and high layer formation efficiency by using the multibeam LMD process. The effects of process parameters such as laser output power and powder feed rate are tied together to explain the geometry of the melt layer as well as the fraction of the laser energy used for melting a material. The experimental results show that the porosity rate and layer formation efficiency were recorded at 0.3% and 0.0042 mm3/J, respectively, at the laser output power of 180 W and a powder feed rate of 75 mg/s. It was revealed that layer formation efficiency was dependent on the laser output power.
{"title":"Experimental evaluation of a WC–Co alloy layer formation process by multibeam-type laser metal deposition with blue diode lasers","authors":"Kosei Yamamoto, Ryuhei Matsuda, K. Takenaka, Yuji Sato, Y. Yamashita, Ayahito Saikai, Taisei Yachi, M. Kusaba, Masahiro Tsukamoto","doi":"10.2351/7.0001125","DOIUrl":"https://doi.org/10.2351/7.0001125","url":null,"abstract":"A tungsten carbide–cobalt (WC–Co) composite layer was formed on a stainless-steel type 304 (SS304) substrate using multibeam laser metal deposition (LMD) with blue diode lasers. This paper aims to provide WC–Co layer formation with low porosity and high layer formation efficiency by using the multibeam LMD process. The effects of process parameters such as laser output power and powder feed rate are tied together to explain the geometry of the melt layer as well as the fraction of the laser energy used for melting a material. The experimental results show that the porosity rate and layer formation efficiency were recorded at 0.3% and 0.0042 mm3/J, respectively, at the laser output power of 180 W and a powder feed rate of 75 mg/s. It was revealed that layer formation efficiency was dependent on the laser output power.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"64 41","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138950508","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}
Skin-pass rolls are used for setting the final sheet thickness and surface texture. For sheet metal that is produced for forming, textured skin-pass rolls featuring a high-low structure are used in order to improve the formability and paint adhesion of the sheet. In this paper, new textures for skin-pass rolls generated by high-speed laser melt injection (HSLMI) are presented and characterized. Furthermore, it is studied how the texture of the roll is transferred to steel and aluminum sheets. With HSLMI, metal matrix composite (MMC) layers featuring spherical fused tungsten carbide (SFTC) particles with a high hardness could be produced on skin-pass rolls. For generating an increased high-low structure, laser ablation and electrolytic etching were carried out after HSLMI and grinding of the rolls. An analysis of the topography showed that different protruding heights between SFTC particles and matrix can be set. The textures generated by laser ablation showed a topography featuring two homogeneous height levels, whereas a texture with spherically shaped particles could be generated by electrolytic etching. Furthermore, it was found that all textures were transferred from the roll to both steel and aluminum sheets. The transfer of the textures mainly depended on the protruding height of the SFTC particles and the SFTC particle content of the roll.
{"title":"Texturing skin-pass rolls by high-speed laser melt injection, laser ablation, and electrolytic etching","authors":"P. Warneke, A. Bohlen, T. Seefeld","doi":"10.2351/7.0001149","DOIUrl":"https://doi.org/10.2351/7.0001149","url":null,"abstract":"Skin-pass rolls are used for setting the final sheet thickness and surface texture. For sheet metal that is produced for forming, textured skin-pass rolls featuring a high-low structure are used in order to improve the formability and paint adhesion of the sheet. In this paper, new textures for skin-pass rolls generated by high-speed laser melt injection (HSLMI) are presented and characterized. Furthermore, it is studied how the texture of the roll is transferred to steel and aluminum sheets. With HSLMI, metal matrix composite (MMC) layers featuring spherical fused tungsten carbide (SFTC) particles with a high hardness could be produced on skin-pass rolls. For generating an increased high-low structure, laser ablation and electrolytic etching were carried out after HSLMI and grinding of the rolls. An analysis of the topography showed that different protruding heights between SFTC particles and matrix can be set. The textures generated by laser ablation showed a topography featuring two homogeneous height levels, whereas a texture with spherically shaped particles could be generated by electrolytic etching. Furthermore, it was found that all textures were transferred from the roll to both steel and aluminum sheets. The transfer of the textures mainly depended on the protruding height of the SFTC particles and the SFTC particle content of the roll.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"15 7","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138952039","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}
B. Panda, Seshadev Sahoo, Cheruvu Siva Kumar, Ashish Kumar Nath
The utilization of the laser powder bed fusion (L-PBF) method in additive manufacturing experiments has revealed the intriguing potential to induce morphological evolutions within the solidification microstructure by manipulating the thermal conditions. Transitions of this nature can have a substantial impact on the ultimate texture and material properties of the product. This study utilizes numerical investigations to examine the microstructure evolution of the AlSi10Mg alloy, which is fabricated using the L-PBF process, under different thermal conditions. In order to investigate the changes in the microstructure, we employ a parameter phase-field (PF) model. This model effectively replicates the natural development of nuclei from inoculant particles and accurately simulates the transitions in the morphology. The PF model’s validity is determined through the numerical investigation of morphological transitions during directional solidification of the AlSi10Mg alloy. The model’s predictions are then compared to the analytical Hunt model. The formation of a columnar microstructure with a significantly reduced secondary dendrite arm spacing is observed when the ratio of the temperature gradient (G) to the solidification rate (R) is increased.
{"title":"Investigating the influence of thermal behavior on microstructure during solidification in laser powder bed fusion of AlSi10Mg alloys: A phase-field analysis","authors":"B. Panda, Seshadev Sahoo, Cheruvu Siva Kumar, Ashish Kumar Nath","doi":"10.2351/7.0001243","DOIUrl":"https://doi.org/10.2351/7.0001243","url":null,"abstract":"The utilization of the laser powder bed fusion (L-PBF) method in additive manufacturing experiments has revealed the intriguing potential to induce morphological evolutions within the solidification microstructure by manipulating the thermal conditions. Transitions of this nature can have a substantial impact on the ultimate texture and material properties of the product. This study utilizes numerical investigations to examine the microstructure evolution of the AlSi10Mg alloy, which is fabricated using the L-PBF process, under different thermal conditions. In order to investigate the changes in the microstructure, we employ a parameter phase-field (PF) model. This model effectively replicates the natural development of nuclei from inoculant particles and accurately simulates the transitions in the morphology. The PF model’s validity is determined through the numerical investigation of morphological transitions during directional solidification of the AlSi10Mg alloy. The model’s predictions are then compared to the analytical Hunt model. The formation of a columnar microstructure with a significantly reduced secondary dendrite arm spacing is observed when the ratio of the temperature gradient (G) to the solidification rate (R) is increased.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"40 13","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138996053","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}
Aqeel Mohd, Gautam J. P., Anusha E., Shariff S. M.
In the present study, a high beam quality fiber-coupled diode laser was effectively utilized to weld 10-mm thick Inconel 617 superalloy in single pass. Influence of critical parameters of focusing distance and welding speed on weld characteristics was systematically investigated and optimized. At optimum process conditions with the power density of ≈106 W/cm2, crack-free full-penetration weld with minimal distortion, porosity, and no underfill/undercut/root-hump defects were obtained with 97%–99% joint efficiency. The weld joint quality produced was on par with multipass employing conventional lasers and advanced laser-hybrid welding techniques and sufficient enough to apply in various applications of thermal power plants, ship building, and heavy industries.
{"title":"High-power fiber-coupled diode laser welding of 10-mm thick Inconel 617 superalloy","authors":"Aqeel Mohd, Gautam J. P., Anusha E., Shariff S. M.","doi":"10.2351/7.0001209","DOIUrl":"https://doi.org/10.2351/7.0001209","url":null,"abstract":"In the present study, a high beam quality fiber-coupled diode laser was effectively utilized to weld 10-mm thick Inconel 617 superalloy in single pass. Influence of critical parameters of focusing distance and welding speed on weld characteristics was systematically investigated and optimized. At optimum process conditions with the power density of ≈106 W/cm2, crack-free full-penetration weld with minimal distortion, porosity, and no underfill/undercut/root-hump defects were obtained with 97%–99% joint efficiency. The weld joint quality produced was on par with multipass employing conventional lasers and advanced laser-hybrid welding techniques and sufficient enough to apply in various applications of thermal power plants, ship building, and heavy industries.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"72 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138998068","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}
Additive manufacturing of copper using laser powder bed fusion enables the production of highly complex components with excellent heat and electrical conductivity. However, the processing of copper by means of near-infrared laser radiation, which is commonly used, is challenging due to its high reflectivity. Nevertheless, it has been demonstrated that high densities and electrical conductivities can be achieved using high-power laser systems. In order to process pure copper with reliable quality with different machines, it is essential to understand the conditions at which a continuous weld track is formed. For this purpose, weld tracks with varying laser power and scan speeds were welded on a copper substrate plate with an applied powder layer. The preheating temperature of the substrate plate and the beam size were varied to test different process conditions. The melt pool depths and widths were measured, and a relationship was elaborated. Based on these results, cube samples with discrete weld tracks on top were manufactured. The melt pool depth was measured and compared with the predicted melt pool depth to investigate the transferability of the elaborated relationship from the substrate to process conditions. It was found that with rising preheating temperature and for larger beam diameters at the same peak intensity, the weld width and weld depths increase. Furthermore, continuous weld tracks formed reliably in the keyhole welding regime. A good agreement between the weld depth of weld tracks on the substrate and the elaborated relationship was revealed. However, the weld tracks were shallower than predicted.
{"title":"Influence of temperature and beam size on weld track shape in laser powder bed fusion of pure copper using near-infrared laser system","authors":"Alexander Bauch, Dirk Herzog","doi":"10.2351/7.0001118","DOIUrl":"https://doi.org/10.2351/7.0001118","url":null,"abstract":"Additive manufacturing of copper using laser powder bed fusion enables the production of highly complex components with excellent heat and electrical conductivity. However, the processing of copper by means of near-infrared laser radiation, which is commonly used, is challenging due to its high reflectivity. Nevertheless, it has been demonstrated that high densities and electrical conductivities can be achieved using high-power laser systems. In order to process pure copper with reliable quality with different machines, it is essential to understand the conditions at which a continuous weld track is formed. For this purpose, weld tracks with varying laser power and scan speeds were welded on a copper substrate plate with an applied powder layer. The preheating temperature of the substrate plate and the beam size were varied to test different process conditions. The melt pool depths and widths were measured, and a relationship was elaborated. Based on these results, cube samples with discrete weld tracks on top were manufactured. The melt pool depth was measured and compared with the predicted melt pool depth to investigate the transferability of the elaborated relationship from the substrate to process conditions. It was found that with rising preheating temperature and for larger beam diameters at the same peak intensity, the weld width and weld depths increase. Furthermore, continuous weld tracks formed reliably in the keyhole welding regime. A good agreement between the weld depth of weld tracks on the substrate and the elaborated relationship was revealed. However, the weld tracks were shallower than predicted.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"38 4","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138971167","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}
Yang Zou, Shaoqi Shi, Zefeng Yang, Teng Xu, Yongqi Liang, Qiang Yu, Yuchuan Cheng, Gaojie Xu, Zhixiang Li, Fei Long
Laser cladding (LC) process parameters have a substantial influence on coating morphology and mechanical characteristics; it is necessary to optimize key parameters for laser processing. In this study, Stellite12 cobalt-based alloy powder with excellent corrosion and wear resistance was selected as the cladding material. The multi-objective optimization model of the LC process was established by response surface methodology, laser power, scanning speed, and powder feeding rate as input factors, and the target response variables involve dilution, aspect ratio, and microhardness of the single-track cladding. Combined with variance analysis (ANOVA), the multi-objective optimization of laser power, scanning speed, and powder feeding rate was conducted. A single-track cladding layer with a dilution of 18.29%, an aspect ratio of 3.88, and a microhardness of 634.67 HV0.2 was obtained using the optimized process parameters. Errors between the predicted and actual values of single-track cladding dilution, aspect ratio, and microhardness were less than 8%, which verified the accuracy of the established model.
{"title":"Multi-objective optimization of key process parameters in laser cladding Stellite12 cobalt-based alloy powder","authors":"Yang Zou, Shaoqi Shi, Zefeng Yang, Teng Xu, Yongqi Liang, Qiang Yu, Yuchuan Cheng, Gaojie Xu, Zhixiang Li, Fei Long","doi":"10.2351/7.0001163","DOIUrl":"https://doi.org/10.2351/7.0001163","url":null,"abstract":"Laser cladding (LC) process parameters have a substantial influence on coating morphology and mechanical characteristics; it is necessary to optimize key parameters for laser processing. In this study, Stellite12 cobalt-based alloy powder with excellent corrosion and wear resistance was selected as the cladding material. The multi-objective optimization model of the LC process was established by response surface methodology, laser power, scanning speed, and powder feeding rate as input factors, and the target response variables involve dilution, aspect ratio, and microhardness of the single-track cladding. Combined with variance analysis (ANOVA), the multi-objective optimization of laser power, scanning speed, and powder feeding rate was conducted. A single-track cladding layer with a dilution of 18.29%, an aspect ratio of 3.88, and a microhardness of 634.67 HV0.2 was obtained using the optimized process parameters. Errors between the predicted and actual values of single-track cladding dilution, aspect ratio, and microhardness were less than 8%, which verified the accuracy of the established model.","PeriodicalId":50168,"journal":{"name":"Journal of Laser Applications","volume":"10 11","pages":""},"PeriodicalIF":2.1,"publicationDate":"2023-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139004791","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}
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":"2 7","pages":""},"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":"24 20","pages":""},"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":"19 6","pages":""},"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":"139 3","pages":""},"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}
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