Permeability Performance on Porous Structure of Injection Mold Fabricated by Metal Laser Sintering Combined with High Speed Milling

Narahara, Hiroyuki; Takeshita, Sho; Fukumaru, Hirofumi; Koresawa, Hiroshi; Suzuki, Hiroshi

doi:10.20965/ijat.2012.p0576

Cited by 16 publications

(4 citation statements)

References 9 publications

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“…Another example is the porous mold inserts in plastic injection molding for gas escape to avoid flow lines, short shots, burn marks defects, etc. [6][7][8][9][10]. Among these applications, fluidity is critical inside the cellular parts.…”

Section: Introductionmentioning

confidence: 99%

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Permeability of Additive Manufactured Cellular Structures—A Parametric Study on 17-4 PH Steels, Inconel 718, and Ti-6Al-4V Alloys

Liu

Cheng²,

Chiu³

et al. 2022

JMMP

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Cellular structures of metallic alloys are often made for various industrial applications by additive manufacturing. The permeability for fluid flow in these cellular structures is important. The current investigated the gas fluidity of cellular structures made by selective laser melting (SLM). The porosity and permeability of the SLM cellular structures were measured for 17-4 PH stainless steel, Inconel 718, and Ti-6Al-4V alloys. The relations between porosity and energy density are expressed using the power law. The characteristic molar energies were 1.07 × 105, 9.02 × 104, and 7.11 × 104 J/mole for 17-4 PH steel, Ti-6Al-4V, and Inconel 718 alloys, respectively. 17-4 PH steel gave rise to higher porosity at the same energy density when compared with Ti-6Al-4V and Inconel 718 alloy. The values of these molar energy density are related to the heat needed to melt the alloys, viscosity, and thermal conductivity. It was further shown that air permeability is not only concerned with the percentage of porosity in the cellular materials, but it also relates to the tortuosity of pore pathways formed in the cellular materials. At the same porosity, Inconel 718 demonstrates higher air permeability in comparison with that of Ti-6Al-4V and 17-4 PH alloys due to its smoother pore pathways. Ti-6Al-4V, on the other hand, demonstrates the highest specific surface areas due to powder sticking along the pore pathways and led to the lowest permeability among the three alloys.

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Section: Introductionmentioning

confidence: 99%

“…Pore arrangements in the cellular metals made by these processes cannot be controlled. Additive manufacturing becomes a reasonable candidate for manufacturing three-dimensional structures with desired cellular structures [10,13].…”

Section: Introductionmentioning

confidence: 99%

Permeability of Additive Manufactured Cellular Structures—A Parametric Study on 17-4 PH Steels, Inconel 718, and Ti-6Al-4V Alloys

Liu

Cheng²,

Chiu³

et al. 2022

JMMP

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“…The current work will provide a guideline for selecting porous parts and their printing parameters based on the permeability needed according to the design of injection parts. Air permeability is obtained according to the Darcy equation by relating pressure drop and flow rate of escaping gas through the porous inserts [ 17 ]. In the current study, the cellular parts were prepared using maraging steel by SLM process.…”

Section: Introductionmentioning

confidence: 99%

Air Permeability of Maraging Steel Cellular Parts Made by Selective Laser Melting

Dhinakar

Chang³

et al. 2021

Materials

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Additive manufacturing, such as selective laser melting (SLM), can be used to manufacture cellular parts. In this study, cellular coupons of maraging steels are prepared through SLM by varying hatch distance. Air flow and permeability of porous maraging steel blocks are obtained for samples of different thickness based on the Darcy equation. By reducing hatch distance from 0.75 to 0.4 mm, the permeability decreases from 1.664 × 10−6 mm2 to 0.991 × 10−6 mm2 for 4 mm thick coupons. In addition, by increasing the thickness from 2 to 8 mm, the permeability increases from 0.741 × 10−6 mm2 to 1.345 × 10−6 mm2 at 16.2 J/mm3 energy density and 0.14 MPa inlet pressure. Simulation using ANSYS-Fluent is conducted to observe the pressure difference across the porous coupons and is compared with the experimental results. Surface artifacts and the actual morphology of scan lines can cause the simulated permeability to deviate from the experimental values. The measured permeability of maraging steel coupons is regression fit with both energy density and size of samples which provide a design guideline of porous mold inserts for industry applications such as injection molding.

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“…However, for many applications the high surface roughness produced by AM techniques demands a post-finishing operation to improve the surface quality prior to usage. Current methods to reduce the surface roughness include traditional machining such as belt grinding or milling [6], chemical etching for porous structures [7], and re-melting by either laser polishing [8,9] or large area electron beam irradiation [10]. Reduction down to 2-3 μm Ra (from 22 to 45 μm Ra) was reported for additively manufactured titanium alloy parts using laser polishing.…”

Section: Introductionmentioning

confidence: 99%

Finishing of additively manufactured titanium alloy by shape adaptive grinding (SAG)

Beaucamp

Namba

Charlton

et al. 2015

Surf. Topogr.: Metrol. Prop.

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In recent years, rapid prototyping of titanium alloy components for medical and aeronautics application has become viable thanks to advances in technologies such as electron beam melting (EBM) and selective laser sintering (SLS). However, for many applications the high surface roughness generated by additive manufacturing techniques demands a post-finishing operation to improve the surface quality prior to usage. In this paper, the novel shape adaptive grinding process has been applied to finishing titanium alloy (Ti6Al4V) additively manufactured by EBM and SLS. It is shown that the micro-structured surface layer resulting from the melting process can be removed, and the surface can then be smoothed down to less than 10 nm Ra (starting from 4-5 μm Ra) using only three different diamond grit sizes. This paper also demonstrates application of the technology to freeform shapes, and documents the dimensional accuracy of finished artifacts.

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Permeability Performance on Porous Structure of Injection Mold Fabricated by Metal Laser Sintering Combined with High Speed Milling

Cited by 16 publications

References 9 publications

Permeability of Additive Manufactured Cellular Structures—A Parametric Study on 17-4 PH Steels, Inconel 718, and Ti-6Al-4V Alloys

Permeability of Additive Manufactured Cellular Structures—A Parametric Study on 17-4 PH Steels, Inconel 718, and Ti-6Al-4V Alloys

Air Permeability of Maraging Steel Cellular Parts Made by Selective Laser Melting

Finishing of additively manufactured titanium alloy by shape adaptive grinding (SAG)

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