Controlled Porosity Structures in Aluminum and Titanium Alloys by Selective Laser Melting

Calignano, Flaviana; Cattano, Giulio; Iuliano, Luca; Manfredi, Diego

doi:10.1007/978-3-319-66866-6_18

Cited by 6 publications

(5 citation statements)

References 25 publications

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“…The literature regarding the intentional introduction of stochastic porosity within parts fabricated with powder bed fusion processes is sparse, as this is generally an undesired result and significant effort has been directed at eliminating porosity in nominally solid parts. Nevertheless, stochastic porosities of up to 45% have been reported in aluminum and titanium alloys [30]. The porosity is generally induced by varying the process parameters, including hatch spacing (the distance between adjacent laser passes) and scanning speed [31].…”

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confidence: 99%

A permeable-membrane microchannel heat sink made by additive manufacturing

Collins

Weibel

Pan

et al. 2019

International Journal of Heat and Mass Transfer

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Microchannel heat sinks are capable of removing dense heat loads from high-power electronic devices with low thermal resistance, but suffer from high pressure drops due to the small channel dimensions. Features that reduce the pressure drop, such as manifolds, increase fabrication complexity and are constrained by traditional subtractive manufacturing approaches. Additive manufacturing technologies offer improved design freedom and reduced geometric restrictions, expanding the types of features that can be produced and integrated into a heat sink. In this work, a novel permeable membrane microchannel (PMM) heat sink geometry is proposed and fabricated using direct metal laser sintering (DMLS) of an aluminum alloy (AlSi10Mg). In this PMM design, the cooling fluid is forced through thin, porous walls that act as both conducting fins and membranes that allow flow through their fine internal flow features for efficient heat exchange. The design leverages the ability of this fabrication process to incorporate complex, arbitrarily curved structures having internal porosity to enhance heat transfer and reduce pressure drop across the heat sink. The PMM heat sink geometry is benchmarked against a low-pressure-drop manifold microchannel (MMC) heat sink. A reduced-order model is used to explore the relative performance trends between the designs. Both heat sinks are experimentally characterized at flow rates of 50-500 mL/min using deionized water as the working fluid. At a constant pumping power of 0.018 W, the permeable membrane microchannel design offers both lower thermal resistance (17% reduction) and lower pressure drop (28% reduction) compared to the manifold microchannel heat sink.

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confidence: 99%

A permeable-membrane microchannel heat sink made by additive manufacturing

Collins

Weibel

Pan

et al. 2019

International Journal of Heat and Mass Transfer

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“…The manufacturability mainly depends on the process parameters. In (Calignano et al , 2018a, 2018b), Calignano et al analyzed thin-wall structures and foams in aluminum and titanium alloys printed by SLM with different strategies and hatching distances. They found that it was possible to obtain pores of different sizes by adjusting the hatching distance.…”

Section: Experimental Methods and Setupmentioning

confidence: 99%

“…Pawlak et al (2017) used design of experiments (DoE) method to establish an empirical model for the relationship between porosity and processing parameters. Calignano et al (2018a, 2018b) investigated the processing parameters for thin-wall porous structures fabricated by SLM technology. The authors developed mathematical models for thin-wall width and gap width corresponding to laser power, scanning speed, and hatch distance by regression analysis based on analysis of variance (ANOVA) results.…”

Section: Introductionmentioning

confidence: 99%

Manufacturability analysis of extremely fine porous structures for selective laser melting process of Ti6Al4V alloy

Ding

Tan

Chen

et al. 2021

RPJ

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Purpose The manufacturability of extremely fine porous structures in the SLM process has rarely been investigated, leading to unpredicted manufacturing results and preventing steady medical or industrial application. The research objective is to find out the process limitation and key processing parameters for printing fine porous structures so as to give reference for design and manufacturing planning. Design/methodology/approach In metallic AM processes, the difficulty of geometric modeling and manufacturing of structures with pore sizes less than 350 μm exists. The manufacturability of porous structures in selective laser melting (SLM) has rarely been investigated, leading to unpredicted manufacturing results and preventing steady medical or industrial application. To solve this problem, a comprehensive experimental study was conducted to benchmark the manufacturability of the SLM process for extremely fine porous structures (less than 350 um and near a limitation of 100 um) and propose a manufacturing result evaluation method. Numerous porous structure samples were printed to help collect critical datasets for manufacturability analysis. Findings The results show that the SLM process can achieve an extreme fine feature with a diameter of 90 μm in stable process control, and the process parameters with their control strategies as well as the printing process planning have an important impact on the printing results. A statistical analysis reveals the implicit complex relations between the porous structure geometries and the SLM process parameter settings. Originality/value It is the first time to investigate the manufacturability of extremely fine porous structures of SLM. The method for manufacturability analysis and printing parameter control of fine porous structure are discussed.

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“…Other research has attempted to produce porous structures by using alternative printing parameters, increasing the hatch distance to produce separated, thin walls close to each other. In that case, solid walls were produced, only suitable for macroscopic structures [12]. The influence of layer thickness, varied in a normal range between 25 and 45 µm for the PBF-LB process, energy density, and laser power on porosity, hardness, and surface quality has been described in another investigation.…”

Section: Mechanisms Of Pore and Weld Track Formationmentioning

confidence: 99%

PBF-LB Process-Induced Regular Cavities for Lightweight AlSi10Mg Structures

2021

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In powder bed fusion with laser beam (PBF-LB), two process-induced defects by pore formation are known: local spherical pores by the keyhole effect and geometrically undefined pores caused by lack of fusion. Both pore types are heterogeneously distributed and can be used for lightweight or damping design applications. The achievable porosity is limited to around 13%. This article presents a novel process-controlled method enabling the targeted and reproducible manufacturing of solid parts with regularly distributed cavities, currently up to 60% porosity in AlSi10Mg, using the balling effect. This eliminates the need for time-consuming digital pre-processing work.

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Controlled Porosity Structures in Aluminum and Titanium Alloys by Selective Laser Melting

Cited by 6 publications

References 25 publications

A permeable-membrane microchannel heat sink made by additive manufacturing

A permeable-membrane microchannel heat sink made by additive manufacturing

Manufacturability analysis of extremely fine porous structures for selective laser melting process of Ti6Al4V alloy

PBF-LB Process-Induced Regular Cavities for Lightweight AlSi10Mg Structures

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