Pub Date : 2025-03-15DOI: 10.1016/j.addlet.2025.100278
Clément Tien , Camille Jean , Lucas Poupaud , Floriane Laverne , Frédéric Segonds
This study investigates the key additive manufacturing (AM) process parameters that influence the dimensional accuracy of dental models produced using the vat photopolymerization Digital Light Processing (DLP) technology. By applying the Taguchi method, 7AM process factors were analyzed. A standardized post-processing protocol was used to maintain consistency, allowing a focused assessment of the printing parameters. Dimensional deviations were analyzed using 3D scanning and point cloud comparison software, with particular attention to reducing warping and shrinkage. The results identified layer thickness, projector power, exposure energy, and vat temperature as the key AM factors affecting the accuracy of the final model. These findings highlight the importance of optimizing these parameters to achieve high-quality dental models, contributing to future advancements in precision and efficiency. Further research is recommended to determine optimal settings for different resins and more complex dental structures.
{"title":"Enhancing dental model accuracy through optimized vat photopolymerization additive manufacturing parameters","authors":"Clément Tien , Camille Jean , Lucas Poupaud , Floriane Laverne , Frédéric Segonds","doi":"10.1016/j.addlet.2025.100278","DOIUrl":"10.1016/j.addlet.2025.100278","url":null,"abstract":"<div><div>This study investigates the key additive manufacturing (AM) process parameters that influence the dimensional accuracy of dental models produced using the vat photopolymerization Digital Light Processing (DLP) technology. By applying the Taguchi method, 7AM process factors were analyzed. A standardized post-processing protocol was used to maintain consistency, allowing a focused assessment of the printing parameters. Dimensional deviations were analyzed using 3D scanning and point cloud comparison software, with particular attention to reducing warping and shrinkage. The results identified layer thickness, projector power, exposure energy, and vat temperature as the key AM factors affecting the accuracy of the final model. These findings highlight the importance of optimizing these parameters to achieve high-quality dental models, contributing to future advancements in precision and efficiency. Further research is recommended to determine optimal settings for different resins and more complex dental structures.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100278"},"PeriodicalIF":4.2,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143687742","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-03-04DOI: 10.1016/j.addlet.2025.100277
Theresa Juarez, Nathan J. Oborny, Andrew Berg, Aaron C. Noell
The development of autonomous life detection instruments is being driven by the advancement of multiple space exploration missions to investigate the subsurface oceans of icy worlds, particularly Titan, Enceladus, and Europa. A fundamental feature of this type of instrument is a compact, reliable, and chemically inert internal liquid transport network. Additively manufactured (AM) custom liquid manifolds produced via vat photopolymerization (VPP) methods can meet these requirements. However, before these materials can be considered, basic spaceflight requirements, qualification for flight worthiness and functionality must be addressed. In this study, mechanical properties, outgassing behavior, polymeric characteristics, and chemical compatibility are assessed for select commercially available AM polymers. The results indicate basic materials qualification requirements are met, including sufficiently characterized mechanical properties, the identification of a bakeout protocol for reduced outgassing to meet NASA standards, and chemical compatibility with liquids and reagents used in candidate instrumentation under development for life detection missions.
{"title":"Qualification of additively manufactured polymer fluid manifolds for life-detection instruments","authors":"Theresa Juarez, Nathan J. Oborny, Andrew Berg, Aaron C. Noell","doi":"10.1016/j.addlet.2025.100277","DOIUrl":"10.1016/j.addlet.2025.100277","url":null,"abstract":"<div><div>The development of autonomous life detection instruments is being driven by the advancement of multiple space exploration missions to investigate the subsurface oceans of icy worlds, particularly Titan, Enceladus, and Europa. A fundamental feature of this type of instrument is a compact, reliable, and chemically inert internal liquid transport network. Additively manufactured (AM) custom liquid manifolds produced via vat photopolymerization (VPP) methods can meet these requirements. However, before these materials can be considered, basic spaceflight requirements, qualification for flight worthiness and functionality must be addressed. In this study, mechanical properties, outgassing behavior, polymeric characteristics, and chemical compatibility are assessed for select commercially available AM polymers. The results indicate basic materials qualification requirements are met, including sufficiently characterized mechanical properties, the identification of a bakeout protocol for reduced outgassing to meet NASA standards, and chemical compatibility with liquids and reagents used in candidate instrumentation under development for life detection missions.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100277"},"PeriodicalIF":4.2,"publicationDate":"2025-03-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143706047","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-18DOI: 10.1016/j.addlet.2025.100276
E. Baharlou , J. Ma
Additive manufacturing in building construction can be extended for mass customization of building components or even complex mold making. This study examines the process parameters of raster orientation of short carbon fiber-reinforced polylactic acid (SCF-PLA) and neat PLA in large-scale 3D printing. Three raster orientations—unidirectional, cross-ply, and quasi-isotropic layups—were printed using a pellet extruder assembled on an industrial robotic arm. Tensile and flexural tests were conducted to characterize the differences between SCF-PLA and neat PLA across all raster orientations. This study shows that neat PLA has higher tensile strength compared to SCF-PLA, and quasi-isotropic orientation can improve the week mechanical properties of both SCF-PLA and PLA. This research highlights the interface bonding challenges encountered with larger 3D printed filaments, which result in more significant pores. Furthermore, any factor that modifies rheological properties of the filament, such as carbon filling, can lead to a higher likelihood of material defects. To understand this discrepancy, microstructure analyses were conducted on intact and fractured 3D printed samples, including the analysis of micro voids, interlayer voids, and bonding between SCF and the PLA matrix. This suggests that the effects of quasi-isotropic layups can be applied to enhance 3D print large-scale polymer-based building components.
{"title":"Effect of raster orientation on large-scale robotic 3D printing of short carbon fiber-reinforced PLA composites","authors":"E. Baharlou , J. Ma","doi":"10.1016/j.addlet.2025.100276","DOIUrl":"10.1016/j.addlet.2025.100276","url":null,"abstract":"<div><div>Additive manufacturing in building construction can be extended for mass customization of building components or even complex mold making. This study examines the process parameters of raster orientation of short carbon fiber-reinforced polylactic acid (SCF-PLA) and neat PLA in large-scale 3D printing. Three raster orientations—unidirectional, cross-ply, and quasi-isotropic layups—were printed using a pellet extruder assembled on an industrial robotic arm. Tensile and flexural tests were conducted to characterize the differences between SCF-PLA and neat PLA across all raster orientations. This study shows that neat PLA has higher tensile strength compared to SCF-PLA, and quasi-isotropic orientation can improve the week mechanical properties of both SCF-PLA and PLA. This research highlights the interface bonding challenges encountered with larger 3D printed filaments, which result in more significant pores. Furthermore, any factor that modifies rheological properties of the filament, such as carbon filling, can lead to a higher likelihood of material defects. To understand this discrepancy, microstructure analyses were conducted on intact and fractured 3D printed samples, including the analysis of micro voids, interlayer voids, and bonding between SCF and the PLA matrix. This suggests that the effects of quasi-isotropic layups can be applied to enhance 3D print large-scale polymer-based building components.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100276"},"PeriodicalIF":4.2,"publicationDate":"2025-02-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143510071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-17DOI: 10.1016/j.addlet.2025.100275
Mingzhang Yang, Ali Rezaei, Mihaela Vlasea
Screening of defective additive manufactured (AM) parts is crucial for ensuring process consistency and part reliability, yet common microstructural inspection methods can be time-consuming or destructive. This study explores how surface analysis combined with machine learning (ML) algorithms can effectively infer the microstructure of laser powder bed fusion (LPBF) parts. As a case study, non-spherical ZrH₂ nanoparticle-enhanced AA7075 aluminum powders was fabricated using 60 different LPBF recipes. ML classification models were then employed to link side-surface topographical features to keyhole melting occurring within the parts. Among the tested ML models, random forest (RF) achieving a testing accuracy of 95 % and an F1-score of 0.98, outperforming both the neural network (NN) and support vector machine (SVM) models. To enhance the interpretability of the ML model, the RF model was leveraged to identify the hierarchical importance of surface features associated with keyhole melting mode. This resulted in the development of keyhole-probability maps based on superficial surface parameters, providing engineers with an effective and easy-to-use tool for screening keyhole mode parts. While further validation is needed, the proposed strategy lays a foundation for leveraging surface topography to infer microstructural features and adapting the method to different material systems.
筛查有缺陷的增材制造（AM）零件对于确保工艺一致性和零件可靠性至关重要，但常见的微观结构检测方法可能会耗费大量时间或具有破坏性。本研究探讨了表面分析与机器学习（ML）算法相结合如何有效地推断激光粉末床熔融（LPBF）零件的微观结构。作为案例研究，使用 60 种不同的 LPBF 配方制造了非球形 ZrH₂ 纳米粒子增强 AA7075 铝粉。然后采用 ML 分类模型将侧面表面地形特征与零件内部发生的锁孔熔化联系起来。在测试的 ML 模型中，随机森林（RF）的测试准确率达到 95%，F1 分数为 0.98，优于神经网络（NN）和支持向量机（SVM）模型。为了提高 ML 模型的可解释性，利用 RF 模型识别了与钥匙孔熔化模式相关的表面特征的层次重要性。这样就开发出了基于表面参数的锁孔概率图，为工程师筛选锁孔模式零件提供了有效且易于使用的工具。虽然还需要进一步验证，但所提出的策略为利用表面形貌推断微观结构特征以及将该方法适用于不同材料系统奠定了基础。
{"title":"Process screening in additive manufacturing: Detection of keyhole mode using surface topography and machine learning","authors":"Mingzhang Yang, Ali Rezaei, Mihaela Vlasea","doi":"10.1016/j.addlet.2025.100275","DOIUrl":"10.1016/j.addlet.2025.100275","url":null,"abstract":"<div><div>Screening of defective additive manufactured (AM) parts is crucial for ensuring process consistency and part reliability, yet common microstructural inspection methods can be time-consuming or destructive. This study explores how surface analysis combined with machine learning (ML) algorithms can effectively infer the microstructure of laser powder bed fusion (LPBF) parts. As a case study, non-spherical ZrH₂ nanoparticle-enhanced AA7075 aluminum powders was fabricated using 60 different LPBF recipes. ML classification models were then employed to link side-surface topographical features to keyhole melting occurring within the parts. Among the tested ML models, random forest (RF) achieving a testing accuracy of 95 % and an F1-score of 0.98, outperforming both the neural network (NN) and support vector machine (SVM) models. To enhance the interpretability of the ML model, the RF model was leveraged to identify the hierarchical importance of surface features associated with keyhole melting mode. This resulted in the development of keyhole-probability maps based on superficial surface parameters, providing engineers with an effective and easy-to-use tool for screening keyhole mode parts. While further validation is needed, the proposed strategy lays a foundation for leveraging surface topography to infer microstructural features and adapting the method to different material systems.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100275"},"PeriodicalIF":4.2,"publicationDate":"2025-02-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143445387","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-10DOI: 10.1016/j.addlet.2025.100274
Isabel B. Prestes, Eric A. Jägle
Metallic Multi-material Additive Manufacturing (MMAM) is an emerging research topic, with potential applications in heat exchangers, metamaterials and satellite components. In recent years, new multi-material laser powder bed fusion (PBF-LB) techniques have been developed. However, processing challenges may arise, since materials with dissimilar properties are mixed at the interfaces, which might lead to defects such as cracks. This work aims to investigate the influence of different laser scan strategies to achieve sound interfaces with different material mixing gradients. The samples, made of Inconel 718 and Invar were deposited by the patterning drums technique and were analyzed by means of optical microscopy and energy-dispersive X-ray spectroscopy (EDS) mappings and line scans. The orientation in which melt pools cross the material interface plays an important role in mixing the materials. Different orientations in subsequent layers create a certain “jagged” pattern of mixing at the interface. Sigmoid functions of Boltzmann fitted to the line scans show a significant slope steepness increase – up to 75 % – in the element count from double scan to single scan, suggesting a stronger material mixing. The double scan strategy leads to porosity at the interface and thus should be avoided. The remelt at the interface partially healed defects such as cracks but does not seem to influence the mixing width at the interface. These findings give general guidance for selecting scan strategies in MMAM depending on the desired mixing pattern at the material interface.
{"title":"Influence of the laser strategy on bi-metallic interfaces printed via multi-material laser-based powder bed fusion","authors":"Isabel B. Prestes, Eric A. Jägle","doi":"10.1016/j.addlet.2025.100274","DOIUrl":"10.1016/j.addlet.2025.100274","url":null,"abstract":"<div><div>Metallic Multi-material Additive Manufacturing (MMAM) is an emerging research topic, with potential applications in heat exchangers, metamaterials and satellite components. In recent years, new multi-material laser powder bed fusion (PBF-LB) techniques have been developed. However, processing challenges may arise, since materials with dissimilar properties are mixed at the interfaces, which might lead to defects such as cracks. This work aims to investigate the influence of different laser scan strategies to achieve sound interfaces with different material mixing gradients. The samples, made of Inconel 718 and Invar were deposited by the patterning drums technique and were analyzed by means of optical microscopy and energy-dispersive X-ray spectroscopy (EDS) mappings and line scans. The orientation in which melt pools cross the material interface plays an important role in mixing the materials. Different orientations in subsequent layers create a certain “jagged” pattern of mixing at the interface. Sigmoid functions of Boltzmann fitted to the line scans show a significant slope steepness increase – up to 75 % – in the element count from double scan to single scan, suggesting a stronger material mixing. The double scan strategy leads to porosity at the interface and thus should be avoided. The remelt at the interface partially healed defects such as cracks but does not seem to influence the mixing width at the interface. These findings give general guidance for selecting scan strategies in MMAM depending on the desired mixing pattern at the material interface.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100274"},"PeriodicalIF":4.2,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143418995","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-09DOI: 10.1016/j.addlet.2025.100273
Brenda Leticia Valadez Mesta , Pascal Thome , Marcus C. Lam , Sammy Tin , Jorge Mireles , Ryan B. Wicker
In laser-based powder bed fusion of metals (PBF-LB/M), variations in laser scanner movements, particularly lesser-studied parameters like scanner delays that control laser directional changes, can influence the microstructure in a part during fabrication as each of typically millions of individual laser vectors impact part thermal history and resulting microstructure. While the impact of commonly researched parameters such as laser power, scan speed, hatch spacing, and layer thickness on part microstructure have been well studied, considerably less attention has been given to scanner delays such as the polygon delay. This study uses electron backscatter diffraction to investigate the microstructural variations caused by polygon delay values ranging from 0 to 450 microseconds, beginning with individual scan tracks. The study then extends single tracks to a simple three-dimensional part to examine if microstructure differences due to polygon delays may be influenced by localized heating and cooling caused by nearby hatch vectors and successive layers. The results reveal that varying polygon delay clearly affects grain morphology during individual scan tracks, although these effects are less clear during a three-dimensional build. Future PBF-LB/M studies should focus more on understanding time-resolved laser beam processing effects to better reduce inconsistencies and improve part quality.
{"title":"Impact of a typical scanner delay processing parameter on local microstructure in metallic laser-based powder bed fusion","authors":"Brenda Leticia Valadez Mesta , Pascal Thome , Marcus C. Lam , Sammy Tin , Jorge Mireles , Ryan B. Wicker","doi":"10.1016/j.addlet.2025.100273","DOIUrl":"10.1016/j.addlet.2025.100273","url":null,"abstract":"<div><div>In laser-based powder bed fusion of metals (PBF-LB/M), variations in laser scanner movements, particularly lesser-studied parameters like scanner delays that control laser directional changes, can influence the microstructure in a part during fabrication as each of typically millions of individual laser vectors impact part thermal history and resulting microstructure. While the impact of commonly researched parameters such as laser power, scan speed, hatch spacing, and layer thickness on part microstructure have been well studied, considerably less attention has been given to scanner delays such as the polygon delay. This study uses electron backscatter diffraction to investigate the microstructural variations caused by polygon delay values ranging from 0 to 450 microseconds, beginning with individual scan tracks. The study then extends single tracks to a simple three-dimensional part to examine if microstructure differences due to polygon delays may be influenced by localized heating and cooling caused by nearby hatch vectors and successive layers. The results reveal that varying polygon delay clearly affects grain morphology during individual scan tracks, although these effects are less clear during a three-dimensional build. Future PBF-LB/M studies should focus more on understanding time-resolved laser beam processing effects to better reduce inconsistencies and improve part quality.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"13 ","pages":"Article 100273"},"PeriodicalIF":4.2,"publicationDate":"2025-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143387863","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.addlet.2024.100261
Rodrigo Zapata Martínez , Shohom Bose-Bandyopadhyay , Alan Burl , Óscar Contreras-Almengor , Carlos Aguilar Vega , Kyle Saleeby , Thomas Kurfess , Andrés Díaz Lantada , Jon Molina-Aldareguia
Nickel-titanium (NiTi) or nitinol alloys exhibit high corrosion resistance, mechanical strength, biocompatibility, and smart properties, rendering them ideal materials for active biomedical devices. Traditional manufacturing techniques struggle with these alloys, prompting the adoption of Laser Powder Bed Fusion (L-PBF) as a viable alternative for producing geometrically challenging features. However, L-PBF inherently introduces geometric inconsistencies and surface defects, necessitating post-processing. Electropolishing and chemical etching, while effective for surface smoothing, result in non-conformal material removal, potentially altering the designed geometry. This study examines the use of machining as a post-processing method to achieve uniform material removal and maintain geometric fidelity. Planar spring-shaped actuators were fabricated via L-PBF and subsequently machined to their final geometry using a Computer Numerical Controlled (CNC) system. The actuators were assessed for geometric accuracy and shape memory properties. Machining of the actuators lead to a near homogeneous thickness of 300 µm in all cases, whereas the electropolished + chemically etched samples varied dramatically from <50 µm to over 400 µm in thickness. The findings demonstrate that CNC machining effectively enhances the geometric precision of L-PBF-manufactured NiTi components, while preserving shape memory characteristics. This research underscores the potential of integrating L-PBF with CNC machining to improve the precision and functionality of NiTi-based biomedical devices.
{"title":"Comparative analysis of machining and electropolishing for surface quality improvement of shape memory nitinol samples additively manufactured by laser powder bed fusion","authors":"Rodrigo Zapata Martínez , Shohom Bose-Bandyopadhyay , Alan Burl , Óscar Contreras-Almengor , Carlos Aguilar Vega , Kyle Saleeby , Thomas Kurfess , Andrés Díaz Lantada , Jon Molina-Aldareguia","doi":"10.1016/j.addlet.2024.100261","DOIUrl":"10.1016/j.addlet.2024.100261","url":null,"abstract":"<div><div>Nickel-titanium (NiTi) or nitinol alloys exhibit high corrosion resistance, mechanical strength, biocompatibility, and smart properties, rendering them ideal materials for active biomedical devices. Traditional manufacturing techniques struggle with these alloys, prompting the adoption of Laser Powder Bed Fusion (L-PBF) as a viable alternative for producing geometrically challenging features. However, L-PBF inherently introduces geometric inconsistencies and surface defects, necessitating post-processing. Electropolishing and chemical etching, while effective for surface smoothing, result in non-conformal material removal, potentially altering the designed geometry. This study examines the use of machining as a post-processing method to achieve uniform material removal and maintain geometric fidelity. Planar spring-shaped actuators were fabricated via L-PBF and subsequently machined to their final geometry using a Computer Numerical Controlled (CNC) system. The actuators were assessed for geometric accuracy and shape memory properties. Machining of the actuators lead to a near homogeneous thickness of 300 µm in all cases, whereas the electropolished + chemically etched samples varied dramatically from <50 µm to over 400 µm in thickness. The findings demonstrate that CNC machining effectively enhances the geometric precision of L-PBF-manufactured NiTi components, while preserving shape memory characteristics. This research underscores the potential of integrating L-PBF with CNC machining to improve the precision and functionality of NiTi-based biomedical devices.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"12 ","pages":"Article 100261"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143179870","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.addlet.2024.100264
Dagoberto Torres-Alvarez, Angel Celis-Guzman, Alan Aguirre-Soto
The degree of mechanical anisotropy in objects printed with laser vat photopolymerization (VPP) remains controversial. It has been stated that objects with a higher degree of mechanical isotropy are produced with VPP as compared to other polymer-based additive manufacturing techniques, such as fused filament fabrication (FFF). However, reports on the evaluation of resin-dependency of the mechanical anisotropy obtained with VPP are scarce. Furthermore, the degree of anisotropy (DA) was quantified using different procedures. Here, six commercial resins were selected to evaluate how the DA correlates to the initial rate of polymerization (RP0), critical energy (EC), and penetration depth (DP) for materials with a broader range of properties. State-of-the-art procedures to calculate the degree of mechanical anisotropy are discussed, and an ideal method is proposed, namely, the ratio of the standard deviations related to the inter- and intra-layer forces: DA=(sdinter/sdintra). The elastic modulus (E) was confirmed isotropic with the three resins that were previously reported. However, objects printed with the additional resins that polymerize at higher initial rates (RP0 =72.1 mM/s) and with lower critical energies (EC = 0.36 mJ/cm2) appear more anisotropic. A linear trend was obtained for the scaling of the mechanical DA with RP0. Moreover, a logarithmic correlation between EC and the DA in E was found, which appears inappropriate for EC as a function of the DA in the maximum stress (σMax). This study aims to spur research on the mechanisms underlying the dependence of the mechanical DA on the resin-curing behavior for objects fabricated by VPP.
{"title":"Resin-dependent mechanical anisotropy in laser vat photopolymerization correlates to the initial rate of polymerization and critical energy","authors":"Dagoberto Torres-Alvarez, Angel Celis-Guzman, Alan Aguirre-Soto","doi":"10.1016/j.addlet.2024.100264","DOIUrl":"10.1016/j.addlet.2024.100264","url":null,"abstract":"<div><div>The degree of mechanical anisotropy in objects printed with laser vat photopolymerization (VPP) remains controversial. It has been stated that objects with a higher degree of mechanical isotropy are produced with VPP as compared to other polymer-based additive manufacturing techniques, such as fused filament fabrication (FFF). However, reports on the evaluation of resin-dependency of the mechanical anisotropy obtained with VPP are scarce. Furthermore, the degree of anisotropy (DA) was quantified using different procedures. Here, six commercial resins were selected to evaluate how the DA correlates to the initial rate of polymerization (R<sub>P0</sub>), critical energy (E<sub>C</sub>), and penetration depth (D<sub>P</sub>) for materials with a broader range of properties. State-of-the-art procedures to calculate the degree of mechanical anisotropy are discussed, and an ideal method is proposed, namely, the ratio of the standard deviations related to the inter- and intra-layer forces: DA=(sd<sub>inter</sub>/sd<sub>intra</sub>). The elastic modulus (<em>E</em>) was confirmed isotropic with the three resins that were previously reported. However, objects printed with the additional resins that polymerize at higher initial rates (R<sub>P0</sub> =72.1 mM/s) and with lower critical energies (E<sub>C</sub> = 0.36 mJ/cm<sup>2</sup>) appear more anisotropic. A linear trend was obtained for the scaling of the mechanical DA with R<sub>P0</sub>. Moreover, a logarithmic correlation between E<sub>C</sub> and the DA in <em>E</em> was found, which appears inappropriate for E<sub>C</sub> as a function of the DA in the maximum stress (σ<sub>Max</sub>). This study aims to spur research on the mechanisms underlying the dependence of the mechanical DA on the resin-curing behavior for objects fabricated by VPP.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"12 ","pages":"Article 100264"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143179871","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.addlet.2024.100266
Julia G. Behnsen , Joseph W. Roberts , Oliver J. Rogan , James M. McArdle , Kate Black
The uniformity of the powder bed in Binder Jet Printing can impact the final properties of additively manufactured components. Granular flow phenomena, such as particle size segregation can influence the uniformity of the powder bed. Due to the 3D nature of the powder bed and the standard requirement for sintering parts following printing, direct experimental observation of the particle distribution and packing density can be difficult. The use of Micro-X-ray-CT however, enables the high-resolution imaging of components manufactured by binder jetting and allows quantification of particle size distribution and packing density throughout the powder bed. This study analyses the periodicity of effects such as in-layer particles size segregation and packing density. The results presented here show that particles segregate by size within each layer of the binder jet printed sample, which resulted in a periodic density change within each layer. The particle size distribution changes over the length of the power-bed, with the volume fraction of smaller particles increased near the front of the powder bed, and the volume fraction of larger particles increased near the back. The insights gained from the Micro-X-ray-CT characterisation approach allow for an enhanced understanding of the powder spreading process in additive manufacturing, paving the way forward for possible part optimisation.
粘合剂喷射印刷中粉末床的均匀性会影响快速成型部件的最终性能。粒度偏析等颗粒流动现象会影响粉末床的均匀性。由于粉末床的三维性质和打印后部件烧结的标准要求，很难对颗粒分布和堆积密度进行直接实验观察。然而，使用 Micro-X 射线-计算机断层扫描可以对通过粘合剂喷射制造的部件进行高分辨率成像，并对整个粉末床的粒度分布和堆积密度进行量化。本研究分析了层内颗粒尺寸偏析和堆积密度等效应的周期性。研究结果表明，在粘合剂喷射打印的样品中，每层内的颗粒都会发生尺寸偏析，从而导致每层内的密度发生周期性变化。颗粒尺寸分布在粉末床的长度方向上发生变化，较小颗粒的体积分数在靠近粉末床前部的位置增加，而较大颗粒的体积分数在靠近粉末床后部的位置增加。从显微 X 射线-计算机断层扫描表征方法中获得的启示有助于加深对增材制造中粉末铺展过程的理解，为可能的零件优化铺平道路。
{"title":"Micro-X-ray-CT for analysis of particle size segregation during powder spreading in Binder Jet Printing","authors":"Julia G. Behnsen , Joseph W. Roberts , Oliver J. Rogan , James M. McArdle , Kate Black","doi":"10.1016/j.addlet.2024.100266","DOIUrl":"10.1016/j.addlet.2024.100266","url":null,"abstract":"<div><div>The uniformity of the powder bed in Binder Jet Printing can impact the final properties of additively manufactured components. Granular flow phenomena, such as particle size segregation can influence the uniformity of the powder bed. Due to the 3D nature of the powder bed and the standard requirement for sintering parts following printing, direct experimental observation of the particle distribution and packing density can be difficult. The use of Micro-X-ray-CT however, enables the high-resolution imaging of components manufactured by binder jetting and allows quantification of particle size distribution and packing density throughout the powder bed. This study analyses the periodicity of effects such as in-layer particles size segregation and packing density. The results presented here show that particles segregate by size within each layer of the binder jet printed sample, which resulted in a periodic density change within each layer. The particle size distribution changes over the length of the power-bed, with the volume fraction of smaller particles increased near the front of the powder bed, and the volume fraction of larger particles increased near the back. The insights gained from the Micro-X-ray-CT characterisation approach allow for an enhanced understanding of the powder spreading process in additive manufacturing, paving the way forward for possible part optimisation.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"12 ","pages":"Article 100266"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-02-01DOI: 10.1016/j.addlet.2024.100265
Daniel Ahlers, Tom Schmolzi, German Junca, Jianwei Zhang, Florens Wasserfall
5-axis 3D printing presents a promising approach to overcome the limitations of traditional 3-axis methods, particularly in the domain of printed electronics where conformal conductive connections are printed onto the surface of freeform objects. However, this additional freedom comes with a demand for high positioning accuracy, as the rotary movements amplify small axis deviations through the lever effect. This paper presents an approach for an automatically self-calibrating low-cost 5-axis printing system using a built-in 3D touch probe. The calibration data is used to generate a precise kinematic printer model in the Unified Robot Description Format (URDF). Our inverse kinematic solver uses this model in our pathplanning software to generate fully compensated G-code trajectories, maintaining the correct position without needing an expensive high-precision motion system. First results are presented as evaluation which were printed on our low-cost 5-axis system with 3D-printed rotary axes, demonstrating the capability to reliably print circuits on imprecise hardware. The calibration process can be executed quickly and automatically every time the printer is restarted. This approach makes multi-axis 3D printing more accessible and increases potential uses, leading to more precise and cost-effective manufacturing solutions.
五轴三维打印技术为克服传统三轴方法的局限性提供了一种前景广阔的方法，尤其是在将保形导电连接打印到自由形态物体表面的打印电子领域。然而，这种额外的自由度对高定位精度提出了要求，因为旋转运动会通过杠杆效应放大小的轴偏差。本文介绍了一种利用内置 3D 触摸探头自动自校准低成本 5 轴打印系统的方法。校准数据用于在统一机器人描述格式（URDF）中生成精确的运动学打印机模型。我们的逆运动学求解器在路径规划软件中使用该模型生成完全补偿的 G 代码轨迹，无需昂贵的高精度运动系统即可保持正确的位置。首批评估结果在我们的低成本五轴系统上打印出来，并带有三维打印的旋转轴，证明了在不精确的硬件上可靠打印电路的能力。每次重新启动打印机时，校准过程都能快速自动执行。这种方法使多轴三维打印更容易获得，并增加了潜在用途，从而带来了更精确、更具成本效益的制造解决方案。
{"title":"Calibration and compensation of 5-axis 3D-printers for printed electronics","authors":"Daniel Ahlers, Tom Schmolzi, German Junca, Jianwei Zhang, Florens Wasserfall","doi":"10.1016/j.addlet.2024.100265","DOIUrl":"10.1016/j.addlet.2024.100265","url":null,"abstract":"<div><div>5-axis 3D printing presents a promising approach to overcome the limitations of traditional 3-axis methods, particularly in the domain of printed electronics where conformal conductive connections are printed onto the surface of freeform objects. However, this additional freedom comes with a demand for high positioning accuracy, as the rotary movements amplify small axis deviations through the lever effect. This paper presents an approach for an automatically self-calibrating low-cost 5-axis printing system using a built-in 3D touch probe. The calibration data is used to generate a precise kinematic printer model in the Unified Robot Description Format (URDF). Our inverse kinematic solver uses this model in our pathplanning software to generate fully compensated G-code trajectories, maintaining the correct position without needing an expensive high-precision motion system. First results are presented as evaluation which were printed on our low-cost 5-axis system with 3D-printed rotary axes, demonstrating the capability to reliably print circuits on imprecise hardware. The calibration process can be executed quickly and automatically every time the printer is restarted. This approach makes multi-axis 3D printing more accessible and increases potential uses, leading to more precise and cost-effective manufacturing solutions.</div></div>","PeriodicalId":72068,"journal":{"name":"Additive manufacturing letters","volume":"12 ","pages":"Article 100265"},"PeriodicalIF":4.2,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143181280","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
扫码关注我们
求助内容：
应助结果提醒方式：
京公网安备 11010802042870号