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A statistical learning method for image-based monitoring of the plume signature in laser powder bed fusion
摘要： The industrial breakthrough of metal additive manufacturing processes mainly involves highly regulated sectors, e.g., aerospace and healthcare, where both part and process qualification are of paramount importance. Because of this, there is an increasing interest for in-situ monitoring tools able to detect process defects and unstable states since their onset stage during the process itself. In-situ measured quantities can be regarded as “signatures” of the process behaviour and proxies of the final part quality. This study relies on the idea that the by-products of laser powder bed fusion (LPBF) can be used as process signatures to design and implement statistical monitoring methods. In particular, this paper proposes a methodology to monitor the LPBF process via in-situ infrared (IR) video imaging of the plume formed by material evaporation and heating of the surrounding gas. The aspect of the plume naturally changes from one frame to another following the natural dynamics of the process: this yields a multimodal pattern of the plume descriptors that limits the effectiveness of traditional statistical monitoring techniques. To cope with this, a nonparametric control charting scheme is proposed, called K-chart, which allows adapting the alarm threshold to the dynamically varying patterns of the monitored data. A real case study in LPBF of zinc powder is presented to demonstrate the capability of detecting the onset of unstable conditions in the presence of a material that, despite being particularly interesting for biomedical applications, imposes quality challenges in LPBF because of its low melting and boiling points. A comparison analysis is presented to highlight the benefits provided by the proposed approach against competitor methods.
关键词： Process plume,Metal additive manufacturing,Laser powder bed fusion,Infrared imaging,In-situ monitoring,Zinc
更新于2025-11-28 14:24:20
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Development of a high strength Al–Zn–Si–Mg–Cu alloy for selective laser melting
摘要： Despite additive manufacturing processes are already widely used in several industrial applications, there are few materials that are specifically designed and optimized for these technologies. Currently, only few Al alloys are available on the market and employed for 3D printing of structural parts. In particular, SieMg bearing alloys are the most common Al alloys for additive manufacturing, featuring high processability but moderate mechanical properties. By this work, we studied the effect of Si addition on the hot cracking susceptibility of a high strength AleZneMgeCu alloy. A preliminary activity has been carried out by blending AleZneMgeCu and AleSieMg powders and analysing their microstructure and properties achieved after selective laser melting. Eventually a new AleZneSieMgeCu alloy has been designed, produced as powder alloy by gas atomization and tested. The microstructure and phase transformations of the new alloy has been investigated by synchrotron X-ray diffraction, differential scanning calorimetry and microscope analysis. The AleZneSieMgeCu alloy processed by selective laser melting featured a relative density of 99.8%, no hot cracks were noticed within the investigated microstructures. The ability of the new alloy to respond to aging starting from both as built and solution annealed conditions has been also evaluated. A good response to direct aging (directly from as built condition) was demonstrated, featuring yield strength and ultimate tensile strength of 402 and 449 MPa, respectively, and hardness of 174 HV after optimized aging at 165 (cid:1)C for 2 h.
关键词： Differential scanning calorimetry,Metal additive manufacturing,Mechanical properties,Synchrotron X-ray diffraction,High strength Al alloy
更新于2025-11-21 11:18:25
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Surface roughness and densification correlation for direct metal laser sintering
摘要： The increasing use of metal additive manufacturing (AM) technologies, such as direct metal laser sintering (DMLS), requires an in-depth understanding of how the optimum DMLS process parameters can be determined to achieve the target properties, such as reduced defect densities and/or desired surface characteristics. To this end, it is important to develop simple strategies that assess part quality and are fast and cost-effective. In this study, the in-plane surface roughness of components fabricated with AM is correlated with the DMLS process parameters and fractional density, enabling rapid and accurate indirect determination of the fractional density of AM components through surface roughness measurements. To this end, two sets of DMLS process parameters and a geometrical parameter are utilized to fabricate more than 150 rectangular cubic samples with varying parameters. All the samples are fabricated using Ti-6Al-4 V powder, which is a frequently used metal alloy for DMLS. Second, two line roughness parameters are defined and measured for all the samples, and their correlations with the DMLS and geometrical parameters are reported. Third, the fractional densities of all the samples are measured and their correlations with the DMLS process parameters are demonstrated. Lastly, a thorough analysis of the observed correlations between the line roughness parameters and fractional density are discussed.
关键词： Ti-6Al-4 V,Surface roughness,Densification,Process parameters,Metal additive manufacturing
更新于2025-09-23 15:21:01
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Characterisation of elemental analysis, carbon sulphur analysis and impact test of stent manufacturing using medical grade ASTM F75 cobalt chromium (CoCrMo) by selective laser melting (SLM) technology
摘要： This paper explains and demonstrates the capabilities of metal additive manufacturing (MAM) technology in producing intricate stent structure with a customise design by using ASTM F75 cobalt chromium powder. The elemental analysis (EDX-SEM), carbon sulphur analysis and Impact Test are being develop and tested and thus exploring the potential area of MAM process for future proof stent manufacturing. By alternatively switching to MAM, the step of production can be minimised and thus customisation of stent can be carried out according to the patient’s need. The suggested model of the stent was taken from the third-party vendor and fabrication was carried out using EOSINT M280 metal printer with the aid of Materialise Magics 19.0 software for support generation.
关键词： stent,scanning electron microscope (SEM),selective laser melting (SLM),cobalt chromium (CoCrMo),energy-dispersive X-ray spectroscopy (EDX),Metal additive manufacturing (MAM)
更新于2025-09-23 15:21:01
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Production Tools Made by Additive Manufacturing Through Laser-based Powder Bed Fusion; Herstellung von Produktionswerkzeugen mittels additiver Fertigung durch laserbasiertes Pulverbettschmelzen;
摘要： This paper deals with the design and production of stamping tools and dies for sheet metal components and injection molds for plastic components. Laser-based Powder Bed Fusion (LPBF) is the additive manufacturing method used in this investigation. Solid and topology optimized stamping tools and dies 3D-printed in DIN 1.2709 (maraging steel) by LPBF are approved/certified for stamping of up to 2-mm thick hot-dip galvanized DP600 (dual-phase steel sheet). The punch in a working station in a progressive die used for stamping of 1-mm thick hot-dip galvanized DP600 is 3D-printed in DIN 1.2709, both with a honeycomb inner structure and after topology optimization, with successful results. 3D printing results in a significant lead time reduction and improved tool material efficiency. The cost of 3D-printed stamping tools and dies is higher than the cost of those made conventionally. The core (inserts) of an injection mold is 3D-printed in DIN 1.2709, conformal cooling optimized and 3D-printed in Uddeholm AM Corrax, and compared with the same core made conventionally. The cooling and cycle time can be improved, if the injection molding core (inserts) is optimized and 3D-printed in Uddeholm AM Corrax. This paper accounts for the results obtained in the above-mentioned investigations.
关键词： Design,Injection molding,Tools,Stamping,Powder bed fusion,Optimization,Topology,Metal,Additive manufacturing,Cooling
更新于2025-09-23 15:19:57
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Crystallographic Orientation Control of 316L Austenitic Stainless Steel via Selective Laser Melting
摘要： In recent years, additive manufacturing has attracted attention as a technology that enables control of the crystallographic texture of metallic materials. We achieved successful control of the crystallographic texture of 316L austenitic stainless steel using selective laser melting (SLM). Three distinguished textures were achieved by changing the laser scan speed, namely: the single crystalline-like texture with {001} orientation in the build direction, the crystallographic lamellar texture in which two kinds of grains with {011} and {001} orientations in the build direction are alternately stacked, and polycrystalline with relatively random orientation. The melt pool shape and the solidification behavior (thermal gradient and migration velocity of solid/liquid interface) in a melt pool could be important controlling factors for the evolution of the crystallographic texture under the SLM process.
关键词： anisotropy,crystallographic texture,metal additive manufacturing (AM),selective laser melting (SLM),melt pool
更新于2025-09-23 15:19:57
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A convolutional neural network for prediction of laser power using melt-pool images in laser powder bed fusion
摘要： In laser powder bed fusion, a convolutional neural network could build a good regression model to predict a laser power value from a melt-pool image. To empirically validate it, we used the acquired image data from a monitoring system inside metal additive manufacturing equipment and optimally configured a convolutional network by the grid search of hyper-parameters. The proposed network showed only 0.12 % of test images were out of the criterion for judging the predicted laser power value to be reliable and showed more accurate results than deep feed-forward neural network in the prediction of laser power states unseen in training steps. We expect that the proposed model could be utilized to discover the problematic position in additive-manufactured layers causing defects during a process.
关键词： convolutional neural network,melt-pool image,process monitoring,metal additive manufacturing,laser powder bed fusion
更新于2025-09-19 17:13:59
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In-situ optical emission spectroscopy of selective laser melting
摘要： The variances in local processing conditions during Selective Laser Melting (SLM), a powder bed Additive Manufacturing (AM) process, can cause defects that lead to part failure. The nature of SLM permits in-situ monitoring of radiometric signals emitted from the part surface during the process, including optical emission from excited alloying elements. Using Optical Emission Spectroscopy (OES) to measure the spectral content of light emitted gives insight into the chemistry and relative intensities of excited species vaporized during SLM processing. The contribution from investigating the use of in-situ OES to gain information about local processing conditions during SLM is reported in this paper. A spectrometer is split into the SLM system laser beam path to measure visible light emitted from the melt pool and plume during the processing of 304L stainless steel. The in-line configuration allows signal collection regardless of the laser scan location. The spectroscopic information is correlated to the melt pool size and features of SLM samples for various build conditions (i.e., process parameters, build chamber atmosphere type, and pressure).The limitations that exist in OES implementation for certain build chamber conditions are discussed. The results in this paper are initial progress towards the use of OES in SLM part qualification and controls applications.
关键词： Metal additive manufacturing,Optical emission spectroscopy,In-situ monitoring,Powder bed fusion
更新于2025-09-19 17:13:59
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Additive Manufacturing of Functionally Graded Metallic Materials Using Laser Metal Deposition
摘要： Functionally graded materials (FGMs) have attracted much research interest in the industry due to their graded material properties, which result from gradually distributed compositions or structures. In recent years, metallic FGMs have been widely studied, and additive manufacturing (AM) has become an important approach to build metallic FGMs. This paper aims to provide an overview of the research progress in metallic FGMs fabricated by laser metal deposition (LMD), an AM process that is widely used in metallic materials. Firstly, the unique material properties and advantages of FGMs are introduced. Then, typical recent findings in transition path design, fabrication, and characterization for different types of metallic FGMs via LMD are summarized and discussed. Finally, challenges in fabricating metallic FGMs via LMD are discussed, and other related aspects in the area of FGMs such as model representation and numerical simulation are proposed for further investigation.
关键词： Laser Metal Deposition,Intermediate Section,Transition Path,Metal Additive Manufacturing,Material Characterization,Functionally Graded Materials
更新于2025-09-16 10:30:52
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In-situ full-field mapping of melt flow dynamics in laser metal additive manufacturing
摘要： Melt flow plays a critical role in laser metal additive manufacturing, yet the melt flow behavior within the melt pool has never been explicitly presented. Here, we report in-situ characterization of melt-flow dynamics in every location of the entire melt pool in laser metal additive manufacturing by populous and uniformly dispersed micro-tracers through in-situ high-resolution synchrotron x-ray imaging. The location-specific flow patterns in different regions of the melt pool are revealed and quantified under both conduction mode and depression mode. The physical processes at different locations in the melt pool are identified. The full-field melt-flow mapping approach reported here opens the way to study the detailed melt-flow dynamics under real additive manufacturing conditions. The results obtained provide crucial insights into laser additive manufacturing processes and are critical for developing reliable high-fidelity computational models.
关键词： x-ray imaging,melt flow,laser processing,powder bed fusion,Metal additive manufacturing
更新于2025-09-12 10:27:22