A study on the effect of energy input on spatter particles creation during selective laser melting process

Andani, Mohsen Taheri; Dehghani, Reza; Karamooz-Ravari, Mohammad Reza; Mirzaeifar, Reza; Ni, Jun

doi:10.1016/j.addma.2017.12.009

Cited by 66 publications

(37 citation statements)

References 17 publications

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“…From the experimental results presented here, it is confirmed that the as-built surface of the investigated AlSi10Mg alloy consists of a number of protruding geometrical features (such as spatters, balling, and partially melted powder particles) that have already been characterized in their morphology, chemistry, microstructure, and mechanisms of formation in the literature [8][9][10]37]. Other studies suggested that by a proper selection of L-PBF process parameters, these features can be reduced in their amount and size [13,38,39], but cannot be fully eliminated, therefore being an unavoidable secondary effect of the laser beam interaction with the matter.…”

Section: Discussionsupporting

confidence: 82%

Effect of Surface and Subsurface Defects on Fatigue Behavior of AlSi10Mg Alloy Processed by Laser Powder Bed Fusion (L-PBF)

Nasab

Giussani²,

Gastaldi

et al. 2019

Metals

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The fatigue behaviour of an AlSi10Mg alloy processed by laser powder bed fusion (L-PBF) and subjected to different surface finishing processes was investigated paying special attention to the residual defects on the surface and the dominant fatigue failure mechanisms. Roughness measurements and qualitative surface morphology analysis showed smooth surfaces in the case of vibro-finishing and machining followed by polishing. The fatigue performance did not reveal to be directly related to surface roughness, but residual intrusions left on the finished surfaces. Post-mortem analysis showed single- or multiple-crack nucleation from pores opened on the surface, un-melted powders, or spatters considered as typical L-PBF defects. A fatigue limit of 195 MPa for machined and polished samples was obtained by substantial removal of surface and subsurface defects.

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Section: Discussionsupporting

confidence: 82%

Effect of Surface and Subsurface Defects on Fatigue Behavior of AlSi10Mg Alloy Processed by Laser Powder Bed Fusion (L-PBF)

Nasab

Giussani²,

Gastaldi

et al. 2019

Metals

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“…-The presence of spatter ejections on the powder bed can also generate porosities. The size of the spatters, usually much larger than the powder grains (< 50 μm), can prevent the powder from spreading homogeneously around the spatter, thus increasing the risk of LOF [10,20]. According to [10] there are three types of spatter ejections : (1) metal jet caused by the recoil pressure of the vapor plume associated with the extreme expansion of the powder phase gas, (2) droplet spatters ejected from the turbulent melt-pool flow, (3) powder spatters generated at the powder layer/melt-pool front interface.…”

Section: Introductionmentioning

confidence: 99%

Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts

Terris

Andreau

Peyre

et al. 2019

Additive Manufacturing

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The systematic occurrence of porosities inside selective laser melted (SLM) parts is a well-known phenomenon. In order to improve the density of SLM parts, it is important not only to assess the physical origin of the different types of porosities, but also to be able to measure as precisely as possible the porosity rate so that one may select the optimum manufacturing parameters. Considering 316 L steel parts built with different input energies, the current paper aims to (1) present the different types of porosities generated by SLM and their origins, (2) compare different methods for measuring parts density and (3) propose optimal procedures. After a preliminary optimization step, three methods were used for quantifying porosity rate: the Archimedes method, the helium pycnometry and micrographic observations. The Archimedes method shows that results depend on the nature and temperature of the fluid, but also on the sample volume and its surface roughness. During the micrographic observations, it has been shown that the results depend on the magnification used and the number of micrographs considered. A comparison of the three methods showed that the optimized Archimedes method and the helium pycnometry technique gave similar results, whereas optimized micrographic observations systematically underestimated the porosity rate. In a second step, samples were analyzed to illustrate the physical phenomena involved in the generation of porosities. It was confirmed that: (1) low Volume Energy Density (VED) causes non-spherical porosities due to insufficient fusion, (2) in intermediary VED the small amount of remaining blowhole porosities come from gas occlusion in the melt-pool and (3) in excessive VED, cavities are formed due to the keyhole welding mode.

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“…Laser melting is generally associated with spatters in the material-laser interaction; the produced spatters exhibit different characteristics when the process parameters vary. It has been shown that spatters are able to produce inclusions and discontinuities in the built parts, which degrade the mechanical properties by decreasing the structural integrity [3,4,31,37,41]. This implies that the characteristics of the spatters under the optimum condition could be systematically analysed and treated as a significant factor to evaluate the manufacture quality during the SLM process.…”

Section: Introductionmentioning

confidence: 99%

“…Spattering is an important phenomenon that is highly related to the quality of the manufactured parts [3,4,37,41,42]. Characterisation and monitoring of spattering behaviours are highly valuable in understanding the manufacturing process and improving the manufacturing quality of SLM.…”

Section: Introductionmentioning

confidence: 99%

“…The appearance of captured spatter trajectories provides rich information in terms of the spattering distributions and motion dynamics that can be understood as the effect of optical flow. As indicated in [3,4,42], the spattering appearance can be considered as the manufacturing process signatures that can be associated with the quality of the build. Limited research has been carried out in investigating in in situ automatic identification of spattering characteristics, as well as the correlation between spattering characteristics and the part quality.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

A novel image feature descriptor for SLM spattering pattern classification using a consumable camera

Han

2020

Int J Adv Manuf Technol

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In selective laser melting (SLM), spattering is an important phenomenon that is highly related to the quality of the manufactured parts. Characterisation and monitoring of spattering behaviours are highly valuable in understanding the manufacturing process and improving the manufacturing quality of SLM. This paper introduces a method of automatic visual classification to distinguish spattering characteristics of SLM processes in different manufacturing conditions. A compact feature descriptor is proposed to represent spattering patterns and its effectiveness is evaluated using real images captured in different conditions. The feature descriptor of this work combines information of spatter trajectory morphology, spatial distributions, and temporal information. The classification is performed using support vector machine (SVM) and random forests for testing and shows highly promising classification accuracy of about 97%. The advantages of this work include compactness for representation and semantic interpretability with the feature description. In addition, the qualities of manufacturing parts are mapped with spattering characteristics under different laser energy densities. Such a map table can be then used to define the desired spatter features, providing a non-contact monitoring solution for online anomaly detection. This work will lead to a further integration of real-time vision monitoring system for an online closed-loop prognostic system for SLM systems, in order to improve the performance in terms of manufacturing quality, power consumption, and fault detection.

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A study on the effect of energy input on spatter particles creation during selective laser melting process

Cited by 66 publications

References 17 publications

Effect of Surface and Subsurface Defects on Fatigue Behavior of AlSi10Mg Alloy Processed by Laser Powder Bed Fusion (L-PBF)

Effect of Surface and Subsurface Defects on Fatigue Behavior of AlSi10Mg Alloy Processed by Laser Powder Bed Fusion (L-PBF)

Optimization and comparison of porosity rate measurement methods of Selective Laser Melted metallic parts

A novel image feature descriptor for SLM spattering pattern classification using a consumable camera

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