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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
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High-performance microwave waveguide devices produced by laser powder bed fusion process
摘要： Additive manufacturing technologies are currently envisaged to boost the development of a next generation of microwave devices intended for satellite telecommunications. Due to their excellent electromagnetic and mechanical properties, metal waveguide components are key building blocks of several radio frequency (RF) systems used in these applications. This article reports the perspectives deriving from the use of laser powder bed fusion (L-PBF) technology to the production of high-performance microwave waveguide devices. A robust design of filters has been implemented in several prototypes manufactured in AlSi10Mg alloy. The corresponding measured performance confirm the applicability of the L-PBF process to the intended applications
关键词： Additive manufacturing,Antenna-feed systems,Laser powder bed fusion
更新于2025-09-12 10:27:22
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Machining induced residual stresses in AlSi10Mg component produced by Laser Powder Bed Fusion (L-PBF)
摘要： The adoption of metal powder-based laser process (L-PBF) for industrial applications continues to widen, due to an increasing knowledge on additive processes and the availability of new systems for industrial production. The use of L-PBF processes requires a deeper investigation and comparison on mechanical properties of conventional and additive parts. For instance, metal parts produced by L-PBF could require additional machining operations, which alter the stress state of additive components. In this work, the effect of machining operations on the residual stress state of an AlSi10Mg component produced by L-PBF is investigated by means of the semi destructive hole-drilling method.
关键词： AlSi10Mg,Machining,Hole-drilling method,Residual stresses,Laser Powder Bed Fusion
更新于2025-09-12 10:27:22
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Implementation of Advanced Laser Control Strategies for Powder Bed Fusion Systems
摘要： Laser path, scan speed, and laser power are critical machine parameters for determining the quality of the output of laser-based powder bed fusion (LPBF) processes. A jerk-limited control strategy is implemented for laser path planning on a LPBF additive manufacturing (AM) testbed. The actual and commanded laser paths/velocities are found to be in better agreement with each other compared to conventional controls. The new controller enabled implementation of advanced laser power control strategies synchronized with laser position and velocity by embedding all into a modified G-code (referred as AM G-code). An interpreter is developed to utilize sophisticated LPBF laser control commands.
关键词： Jerk-limited Control,Scan Strategies,Laser Powder Bed Fusion Additive Manufacturing (LPBF AM),AM G-code
更新于2025-09-12 10:27:22
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Automated Manufacturing of Mechatronic Parts by Laser-Based Powder Bed Fusion
摘要： The powder-bed-based laser beam melting process (L-PBF) has become one of the most reliable and popular additive manufacturing technologies in the field of industrial production of metal components. Moreover, it is constantly evolving to ensure lower costs due to higher productivity as well as to enable the processing of new materials, such as tungsten or copper-alloys. In terms of machine developments, a number of trends are observable. On the one hand, machines become able to produce multi-material parts with an arbitrary distribution of at least two different materials. Therefore, the existing powder delivery system must be adapted. As multiple approaches for doing so already exist, it must be decided which is the most suitable. On the other hand, a further goal is to integrate sensors or actuators automatically, to create structural parts with fully encapsulated electronic components. For this automated process, a pick-and-place concept must be developed and integrated into an existing L-PBF machine. To implement this automated process extension, several adjustments to the system must be implemented. This paper presents approaches for realising the described concepts and the first results of the adapted manufacturing processes.
关键词： smart parts,automated actuator integration,multi-material,powder bed fusion,additive manufacturing,L-PBF process enhancement,automated sensor integration,selective laser melting,SLM
更新于2025-09-12 10:27:22
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Effect of process parameters on the formation of single track in pulsed laser powder bed fusion
摘要： There has been increasing interest in Laser Powder Bed Fusion (L-PBF) of metallic materials as a promising manufacturing technology. Although most L-PBF systems utilize laser beams with continuous wave emission (L-PBF(CW)), the possibility of using pulsed lasers (L-PBF(P)) has become available in some industrial L-PBF machines over the past few years. Previous studies suggest that the use of pulsed lasers could enable larger control of heat input and melt pool formation during the process, and could thus enable improvement of spatial resolution and feature sizes in L-PBF. In this study, the experiments were implemented using a pulsed laser in combination with continuous scanning movement instead of the ‘point-and-shoot’ method typically used by industrial L-PBF(P) machines of today. The experiments were executed using a trial L-PBF system (IPG ytterbium fiber laser, wavelength 1075 nm) for gas-atomized stainless steel 316L powder on compositionally similar substrates. Single tracks were melted with three different pulse lengths (50, 100, and 200 μs) by using a constant layer thickness of 50 μm, while varying pulse repetition rate, scanning speed and laser power based on six preset values of volume energy density (VED) of 36-120 J/mm3. In order to allow a comparison to be made, additional samples were manufactured by using the CW emission of the same laser. It was observed that the L-PBF(P) samples yielded narrower tracks in comparison to the samples manufactured using CW emission. In addition, the results of the experiments show that, while maintaining constant VED values, decreasing the pulse length or scanning speed decreased the widths of the tracks and their penetration into the substrate. Consequently, it was noticed that shorter pulse lengths require more overlap between consecutive pulses in order to produce continuous tracks. Pulsed emission shows potential for improving the spatial resolution of the L-PBF process.
关键词： Laser powder bed fusion,Single track,Pulsed emission,AISI 316L,Additive manufacturing
更新于2025-09-12 10:27:22
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Finite element prediction and validation of residual stress profiles in 316L samples manufactured by laser powder bed fusion
摘要： Laser powder bed fusion (LPBF) processes continue to grow in popularity and much progress has been made in recent years. However, due to the extreme thermal gradients present, significant residual stresses are inevitable and can be detrimental during component service. Critical to mitigating these stresses effectively is the ability to model the thermo-mechanical process accurately and efficiently. A simplified FE modelling methodology has been developed and applied to a cylindrical component built in both the horizontal and vertical orientations. The resulting distortion of the parts following a slitting process was compared with those predicted by the model and good agreement to within 5% was found. The final stress fields in the components were predicted by the model and then examined to assess the principal stresses driving the distortion and the causes of difference in results between the two build orientations.
关键词： LPBF,residual stress,finite element modelling,Laser powder bed fusion,distortion
更新于2025-09-12 10:27:22
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Effects of particle elongation on the binary coalescence dynamics of powder grains for Laser Sintering applications
摘要： In this paper, the effects of particle shape and viscoelasticity on the binary coalescence rates of a pair of PEK HP3 particles in the Laser Sintering (LS) process are investigated in detail. PEK HP3 powder was characterised and the sintering rates were determined using Hot Stage Microscopy (HSM). On average, the neck growth rate shows a slower dynamic compared to the theory. Furthermore, in some of the trials an initial delay in growth and/or a contraction in the neck size was observed. To understand this deviation, the dynamics of individual non-spherical particles were studied at similar conditions. The overall perimeter of the particles shrank and they gradually attained a final spherical state under the effect of surface tension forces which indicates that shape of the individual coalescing units can influence the sintering rates. In addition, the effects of viscoelasticity were investigated using the available theoretical approaches and results show that viscoelasticity can change the rate of coalescence but the neck growth rate shows a strictly increasing trend even for very large Deborah numbers. To investigate the shape effects, volume-of-fluid (VoF) simulations of elongated ellipsoidal particles in head-to-head contact were performed and the neck growth rates were determined. These analyses show that the contraction of the neck size can occur purely due to the geometrical effects and local surface curvatures of the coalescing particles. In addition, a critical aspect ratio exists beyond which the coalescence does not complete and the contraction continues until the pair of coalescing particles eventually separate and form two independent spheres. To explain this phenomenon, the local curvatures along the surface of coalescing particles were calculated and the results show that a local minimum in the curvature at the neck’s contact points with the particle’s main body forms which is believed to drives the separation.
关键词： Laser Sintering,Non-spherical Particles,Powder Bed Fusion,Volume of Fluid,Additive Manufacturing
更新于2025-09-12 10:27:22
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Improving the R&D process efficiency of the selective laser sintering industry through numerical thermal modeling
摘要： The selective laser melting (SLS) industry is a relatively novel industry within the broad spectrum of available additive manufacturing (AM) technologies. As with most developing industries, the primary aim is to develop better quality components at reduced costs, often with a disregard towards efficiency. Resource efficiency is a key component of waste management and ties directly to sustainable manufacturing. In the SLS industry, large quantities of raw material are wasted during the machine calibration stage. Each time a new material is developed for SLS manufacturing a specific set of processing parameters need to be developed in order to ensure that high density, high strength components are produced. This paper investigates the possibility of replacing the current inefficient research and development (R&D) methods with numerical modeling. The fusion process can be simulated in a numerical thermal model using a combination of temperature dependent material properties and heat transfer principles.
关键词： tungsten carbide,powder bed fusion,numerical modeling,Additive manufacturing,process chain
更新于2025-09-12 10:27:22
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Process Design of Laser Powder Bed Fusion of Stainless Steel Using a Gaussian Process-Based Machine Learning Model
摘要： In this work, a Gaussian process (GP)-based machine learning model is developed to predict the remelted depth of single tracks, as a function of combined laser power and laser scan speed in a laser powder bed fusion process. The GP model is trained by both simulation and experimental data from the literature. The mean absolute prediction error magni?ed by the GP model is only 0.6 lm for a powder bed with layer thickness of 30 lm, suggesting the adequacy of the GP model. Then, the process design maps of two metals, 316L and 17-4 PH stainless steels, are developed using the trained model. The normalized enthalpy criterion of identifying keyhole mode is evaluated for both stainless steels. For 316L, the result suggests that the DH (cid:2) 30 criterion hs should be related to the powder layer thickness. For 17-4 PH, the criterion should be revised to DH hs (cid:2) 25.
关键词： stainless steel,process design,Gaussian process,machine learning,laser powder bed fusion
更新于2025-09-12 10:27:22