Surface roughness in laser powder bed fusion – Interdependency of surface orientation and laser incidence

Rott, S.; Ladewig, Alexander; Friedberger, Katrin; Casper, Johannes; Full, Moritz; Schleifenbaum, Johannes Henrich

doi:10.1016/j.addma.2020.101437

Cited by 34 publications

(26 citation statements)

References 22 publications

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“…The study carried out by Kleszczynski et al [28] analyses the impact of increasing the radial distance with respect to the center of the platform, due to the laser beam incidence angle. Since the laser beam is not completely perpendicular to the platform as can be seen in Figure 1 (figure adapted from [33,34]), an increase in the roughness of the parts is obtained. There may be other effects such as partial melting of powder particles due to heat transfer when several parts are manufactured on the same platform.…”

Section: Of 12mentioning

confidence: 99%

“…The study carried out by Kleszczynski et al [28] analyses the impact of increasing the radial distance with respect to the center of the platform, due to the laser beam incidence angle. Since the laser beam is not completely perpendicular to the platform as can be seen in Figure 1 (figure adapted from [33,34]), an increase in the roughness of the parts is obtained. Throughout this article, the effect of the angle of incidence of the laser beam on the surface roughness is detailed, since, after an exhaustive bibliographic study, it seems to be a relevant but not sufficiently studied factor to minimize the resulting surface roughness obtained in the L-PBF process.…”

Section: Of 12mentioning

confidence: 99%

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The Effect of the Laser Incidence Angle in the Surface of L-PBF Processed Parts

Sendino¹,

Gardon²,

Lartategui

et al. 2020

Coatings

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The manufacture of multiple parts on the same platform is a common procedure in the Laser Powder Bed Fusion (L-PBF) process. The main advantage is that the entire working volume of the machine is used and a greater number of parts are obtained, thus reducing inert gas volume, raw powder consumption, and manufacturing time. However, one of the main disadvantages of this method is the possible differences in quality and surface finish of the different parts manufactured on the same platform depending on their orientation and location, even if they are manufactured with the same process parameters and raw powder material. Throughout this study, these surface quality differences were studied, focusing on the variation of the surface roughness with the angle of incidence of the laser with respect to the platform. First, a characterization test was carried out to understand the behavior of the laser in the different areas of the platform. Then, the surface roughness, microstructure, and minimum thickness of vertical walls were analyzed in the different areas of the platform. These results were related to the angle of incidence of the laser. As it was observed, the laser is completely perpendicular only in the center of the platform, whilst at the border of the platform, due to the incidence angle, it melts an elliptical area, which affects the roughness and thickness of the manufactured part. The roughness increases from values of Sa = 5.489 μm in the central part of the platform to 27.473 μm at the outer borders while the thickness of the manufactured thin walls increases around 40 μm.

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Section: Of 12mentioning

confidence: 99%

“…The study carried out by Kleszczynski et al [28] analyses the impact of increasing the radial distance with respect to the center of the platform, due to the laser beam incidence angle. Since the laser beam is not completely perpendicular to the platform as can be seen in Figure 1 (figure adapted from [33,34]), an increase in the roughness of the parts is obtained. Throughout this article, the effect of the angle of incidence of the laser beam on the surface roughness is detailed, since, after an exhaustive bibliographic study, it seems to be a relevant but not sufficiently studied factor to minimize the resulting surface roughness obtained in the L-PBF process.…”

Section: Of 12mentioning

confidence: 99%

The Effect of the Laser Incidence Angle in the Surface of L-PBF Processed Parts

Sendino¹,

Gardon²,

Lartategui

et al. 2020

Coatings

View full text Add to dashboard Cite

show abstract

“…The necessity for such assessment is underlined by investigations which have showed positioning influences‐in build layer dimension‐on surface roughness and the melt pool geometry. [ 24,25 ] Furthermore, nonadjustable parameters such as the shielding gas flow or plume generation might influence the repeatability of parts built with lower energy parameter sets. [ 26,27 ]…”

Section: Introductionmentioning

confidence: 99%

Investigation on Process Stability and Part Positioning Influence on the Relative Density of Designed Materials via Laser‐Based Powder Bed Fusion of Metals on a Multi‐Laser Machine

et al. 2021

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Component production via laser‐based powder bed fusion of metals (PBF‐LB/M) is becoming reality for multiple applications. Especially for sophisticated parts, as in case of gas turbines, assurance of repeatable properties involves control of process and machine parameters. PBF‐LB/M is used to build configurable open‐porous structures—designed materials (DMs)—out of the high temperature superalloy Haynes 282 with relative densities from 35 % to 65 % . The objective is investigating positioning influence and process stability based on their relative densities in discrete scan fields and build jobs. As DMs made from Haynes 282 are not yet scientifically investigated, first the process boundaries are identified. The used PBF‐LB/M machine—EOS M 400‐4—works with four lasers in four quadrants—a quadrant benchmarking is carried out. The experiment is repeated in a second build job. Scatter is identified in quadrant and build job benchmarking. A further aspect under investigation is positioning within laser quadrants. However, keeping laser and parameter combinations constant, sample locations are assessed. A relative density dependency on the laser deflection angle—as a positional measure—is observed. The results of positioning influence and scatter are used to formulate a tolerance equation for relative densities of DMs.

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“…With reference to Figure 7, the green areas on the edges of the build volume fit one sample of CA_F each. Therefore, these volumes are used to investigate the effect of the laser angle (as opposed to the build direction), which is shown to be a decisive factor for surface roughness in LB-PBF/M [39]. On each side of the build space, one sample is fabricated with the cylinder orthogonal to the layers, and one sample is adjusted, so the axis of the cylinder points directly towards the laser origin (the last deflection point, i.e., the last The object inserted in the additional space should be massive enough to significantly contribute to an even slice distribution but also provide additional information that contributes to the validity and reliability of the experiment.…”

Section: Controlling Slice Distributionmentioning

confidence: 99%

“…On each side of the build space, one sample is fabricated with the cylinder orthogonal to the layers, and one sample is adjusted, so the axis of the cylinder points directly towards the laser origin (the last deflection point, i.e., the last With reference to Figure 7, the green areas on the edges of the build volume fit one sample of CA_F each. Therefore, these volumes are used to investigate the effect of the laser angle (as opposed to the build direction), which is shown to be a decisive factor for surface roughness in LB-PBF/M [39]. On each side of the build space, one sample is fabricated with the cylinder orthogonal to the layers, and one sample is adjusted, so the axis of the cylinder points directly towards the laser origin (the last deflection point, i.e., the last mirror before the laser beam enters the build volume).…”

Section: Controlling Slice Distributionmentioning

confidence: 99%

Investigating the Dimensional and Geometric Accuracy of Laser-Based Powder Bed Fusion of PA2200 (PA12): Experiment Design and Execution

Leirmo

Semeniuta

2021

Applied Sciences

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Variation management in additive manufacturing (AM) is progressively more important as technologies are implemented in industrial manufacturing systems; hence massive research efforts are focused on the modeling and optimization of process parameters and the effect on final part quality. These efforts are, however, hampered by the very problem they are seeking to solve, as conclusions are weakened by poor validity, reliability, and repeatability. This paper details an elaborate experiment design and the subsequent execution with the aim of making the research data available without loss of validity. Test artifacts were designed and allocated to fixed positions and orientations in a grid pattern within the build chamber to facilitate rigid analysis between different builds and positions in the build chamber. A total of 507 specimens were produced over three builds by laser sintering PA12 before inspection with a coordinate measuring machine. This research demonstrates the inherent variations of laser-based powder bed fusion of polymers (LB-PBF/P) that must be considered in experiment designs to account for noise factors. In particular, the results indicate that the position in the xy-plane has a major influence on the geometric accuracy, while the position in the z-direction appears to be less influential.

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Surface roughness in laser powder bed fusion – Interdependency of surface orientation and laser incidence

Cited by 34 publications

References 22 publications

The Effect of the Laser Incidence Angle in the Surface of L-PBF Processed Parts

The Effect of the Laser Incidence Angle in the Surface of L-PBF Processed Parts

Investigation on Process Stability and Part Positioning Influence on the Relative Density of Designed Materials via Laser‐Based Powder Bed Fusion of Metals on a Multi‐Laser Machine

Investigating the Dimensional and Geometric Accuracy of Laser-Based Powder Bed Fusion of PA2200 (PA12): Experiment Design and Execution

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