On the influence of inter-layer time and energy density on selected critical-to-quality properties of PA12 parts produced via laser sintering

Pavan, Michele; Faes, Matthias; Strobbe, Dieter; Hooreweder, Brecht Van; Craeghs, Tom; Moens, David; Dewulf, Wim

doi:10.1016/j.polymertesting.2017.05.027

Cited by 71 publications

(35 citation statements)

References 20 publications

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“…The corresponding control points r 1 and r 2 are shown in Fig. 1, and they correspond to zones with a difference in cross-sectional area, as previous work of the authors [19] shows that this influences the local stiffness of Laser Sintered parts. As such, the interval field quantification problem reduces to finding the correct interval scalars using the optimisation problem introduced in eq.…”

Section: Uncertainty In Mechanical Engineering III Case Study: Laser mentioning

confidence: 80%

Inverse Interval Field Quantification via Digital Image Correlation

Faes

Moens

2018

AMM

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This paper presents the application of a new method for the identification and quantification of interval valued spatial uncertainty under scarce data.Specifically, full-field strain measurements, obtained via Digital Image Correlation, are applied in conjunction with a quasi-static finite element model.To apply these high-dimensional but scarce data, extensions to the novel method are introduced.A case study, investigating spatial uncertainty in Young's modulus of PA-12 parts, produced via Laser Sintering, shows that an accurate quantification of the constituting uncertainty is possible, albeit being somewhat conservative with respect to deterministic values reported in literature.

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Section: Uncertainty In Mechanical Engineering III Case Study: Laser mentioning

confidence: 80%

Inverse Interval Field Quantification via Digital Image Correlation

Faes

Moens

2018

AMM

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“…Even for PA-12, the most researched LS material, a considerable amount of non-determinism in the mechanical and dimensional properties was found in previous work (see e.g., [4,5,6]). At the micro-scale, for example, the mechanical material behavior is mainly affected by the local amount of pores and their topology, caused by insufficient sintering and limited powder flow due to short processing times [6,7]. On the meso-scale, non-determinism in part properties such as the local stiffness and dimensional accuracy is caused by changes in inter-layer time (i.e.…”

Section: Introductionmentioning

confidence: 90%

“…Previous research shows that typically, variations in local porosity of 2% to 8% on a length scale of 100 µm [5,37] are encountered. These pores both act as stress concentrators [4], and furthermore reduce the load bearing cross-section area [6]. As such, they influence the local apparent Young's modulus of the material to a large extent.…”

Section: Local Variabilitymentioning

confidence: 99%

“…On the meso-scale, non-determinism in part properties such as the local stiffness and dimensional accuracy is caused by changes in inter-layer time (i.e. the time between the scanning of a certain point of the layer and the recoating operation) between subsequent layers of the part [4,6]. Finally, on the macro-scale of the part, it has been shown that also the location in the build envelope influence the resulting mechanical properties due to inhomogeneities in the pre-heating temperature and the post-building cool-down of the components [8,4].…”

Section: Introductionmentioning

confidence: 99%

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Hybrid spatial uncertainty analysis for the estimation of imprecise failure probabilities in Laser Sintered PA-12 parts

Faes

Sabyasachi

Moens

2019

Computers & Mathematics with Applications

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This paper presents the application of non-determinstic modelling techniques for the quantification of imprecise failure probabilities in PA-12 parts produced via Laser Sintering (LS). Specifically, a modelling approach consisting of a combination of interval and random fields is applied, and the effect hereof on the resulting polymorphic uncertainty in the mechanical performance of the LS parts is studied. A link with the underlying process physics is given, relating the spatial porosity distributions that are inherently present in LS PA12 parts to a spatial distribution in the apparent Young's modulus. Furthermore, uncertainty on the final dimensions of other parts that are constructed in the same build envelope as the designed part is linked to uncertainty in the cross-sectional area of the designed part. The effect of these sources of uncertainty is studied in three case studies, illustrating the need for a well-thought production process planning given the influence on the resulting mechanical performance of the designed structure. Especially the effect of epistemic uncertainty on the design process is shown to be significant.

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“…However, when the energy density was extremely high, degradation of the polymer occurred. Pavan et al [9] estimated the thermo-temporal eff ect infl uenced by the energy density and the inter-layer time, on the resulting SLS PA12 part quality at both the micro-level and macro-level, but ignored the infl uence of layer thickness. In recent years, with the ever-growing development of computer software, many researchers have applied numerical analysis to simulate the sintering processes and microscopic evolution [10][11][12][13][14] .…”

mentioning

confidence: 99%

Effects of process parameters on dimensional precision and tensile strength of wax patterns for investment casting by selective laser sintering

Wei

Wang

et al. 2018

China Foundry

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T he wax patterns of single-crystal superalloy turbine blade, with the necessary complex shapes and high dimensional accuracy, are mainly manufactured by waxinjectors. Traditional wax pattern materials are paraffi nstearin, paraffin-polyolefin, and modified rosin, etc. The traditional wax pattern is prepared using the wax injector, followed by the dipping in the ceramic slurry, stuccoing, and drying, then a ceramic shell mould is obtained. The quality of the turbine blades depends heavily on this series of processes. Fabricating the wax pattern is the fi rst step in the investment casting process, and its processing quality is transmitted to the ceramic shell and then to the fi nal casting [1-2]. Accordingly, the quality of the wax pattern plays a significant role in the entire casting process, which is a time-consuming and laborious work. Furthermore, the quality of the Abstract: Turbine blades, produced by the directional solidifi cation (DS) process, often require high dimensional accuracy and excellent mechanical properties. A critical step in their production is the fabrication of wax patterns. However, the traditional manufacturing process has many disadvantages, such as long-term production, low material utilization rate, and the high cost of producing a complex-shaped wax pattern. Selective laser sintering (SLS) is one of the most extensively used additive manufacturing techniques that substantially shortens the production cycle. In this study, SLS was adopted to fabricate the wax pattern instead of the traditional manufacturing process. The orthogonal experiment method was carried out to investigate the effects of laser power, scanning speed, scanning space, and layer thickness on the dimensional precision and morphologies of the SLS parts. The SLS parts showed a minimum dimensional deviation when laser power, scanning speed, scanning space, and layer thickness were 10 W, 3000 mm•s-1 , 0.18 mm, and 0.25 mm, respectively. In addition, the tensile strength and fracture morphologies were closely associated with the laser volumetric energy density (VED). The tensile strength reached a maximum when the VED was 0.0762 J•mm-3 , with an evident brittle fracture morphology. The wax pattern manufactured in this way meets the accuracy and strength requirements for investment casting. This research offers a novel path for the production of wax patterns for complex-shaped turbine blades by SLS.

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On the influence of inter-layer time and energy density on selected critical-to-quality properties of PA12 parts produced via laser sintering

Cited by 71 publications

References 20 publications

Inverse Interval Field Quantification via Digital Image Correlation

Inverse Interval Field Quantification via Digital Image Correlation

Hybrid spatial uncertainty analysis for the estimation of imprecise failure probabilities in Laser Sintered PA-12 parts

Effects of process parameters on dimensional precision and tensile strength of wax patterns for investment casting by selective laser sintering

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