Numerical simulation and experimental investigation of mold filling and segregation in low-pressure powder injection molding of metallic feedstock

Trad, Mohamed Aziz Ben; Demers, Vincent; Côté, Raphaël; Sardarian, Mehran; Dufresne, Louis

doi:10.1016/j.apt.2020.01.018

Cited by 17 publications

(9 citation statements)

References 21 publications

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“…A low value of E is suitable to minimize sudden viscosity changes between the injection press's hot and cold zones. Furthermore, the E value decreases as the particle size increases [37].…”

Section: Rheological Propertiesmentioning

confidence: 94%

“…Different techniques can be used to create these powders like gas atomization, water atomization thermal decomposition and chemical reduction [2]. Each method will influence the powder characteristics and, therefore, the final component's density, dimensions, and distortion [37,[41][42][43]. Suitable PIM powders are sufficiently small and sinterable but do not exhibit strong sintering behavior at temperatures where binders are removed.…”

Section: Powdermentioning

confidence: 99%

“…In addition, the green part shrinkage is simultaneously decreased. LPIM feedstocks are typically injected at pressures between 0.7 and 20 MPa (7 and 200 bar) in many studies [32,33,35,37]. The amount of pressure that can be increased depends on the viscosity, but in practice, only an increase between 0.5-0.7 MPa is feasible.…”

Section: Parameters and Defectsmentioning

confidence: 99%

“…Research groups have used LPIM to produce parts out of metals, ceramics, and carbides, including 316-L stainless steel [30], Inconel 718 superalloy [31], alumina [32], cemented tungsten carbide [33], and near-net-shape ceramic parts in the range of 100-10,000 units [34]. Current research focuses on developing experimental methods and numerical simulations to examine the impact of powder characteristics, injection parameters, and feedstock features on metal powder and binder segregation during injection molding [35][36][37]. Recent developments in LPIM can be attributed to the impressive growth rate of conventional PIM technology and the new requirements brought in by the automotive, medical, and aerospace sectors [38].…”

Section: Introductionmentioning

confidence: 99%

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Research Progress on Low-Pressure Powder Injection Molding

et al. 2022

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Powder injection molding (PIM) is a well-known technique to manufacture net-shaped, complicated, macro or micro parts employing a wide range of materials and alloys. Depending on the pressure applied to inject the feedstock, this process can be separated into low-pressure (LPIM) and high-pressure (HPIM) injection molding. Although the LPIM and HPIM processes are theoretically similar, all steps have substantial differences, particularly feedstock preparation, injection, and debinding. After decades of focusing on HPIM, low-viscosity feedstocks with improved flowability have recently been produced utilizing low-molecular-weight polymers for LPIM. It has been proven that LPIM can be used for making parts in low quantities or mass production. Compared to HPIM, which could only be used for the mass production of metallic and ceramic components, LPIM can give an outstanding opportunity to cover applications in low or large batch production rates. Due to the use of low-cost equipment, LPIM also provides several economic benefits. However, establishing an optimal binder system for all powders that should be injected at extremely low pressures (below 1 MPa) is challenging. Therefore, various defects may occur throughout the mixing, injection, debinding, and sintering stages. Since all steps in the process are interrelated, it is important to have a general picture of the whole process which needs a scientific overview. This paper reviews the potential of LPIM and the characteristics of all steps. A complete academic and research background survey on the applications, challenges, and prospects has been indicated. It can be concluded that although many challenges of LPIM have been solved, it could be a proper solution to use this process and materials in developing new applications for technologies such as additive manufacturing and processing of sensitive alloys.

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“…A low value of E is suitable to minimize sudden viscosity changes between the injection press's hot and cold zones. Furthermore, the E value decreases as the particle size increases [37].…”

Section: Rheological Propertiesmentioning

confidence: 94%

Section: Powdermentioning

confidence: 99%

Section: Parameters and Defectsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Research Progress on Low-Pressure Powder Injection Molding

et al. 2022

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“…The numerical model simulates the injection and packing step of injection process, but not the solidification phase. The numerical model considered four governing equations: conservation of mass, conservation of momentum, energy balance and particle-phase mass balanced [ 31 ], listed hereinafter. The conservation of mass equation is as follows:

where

is the density of the suspension, t represents the time and

is the velocity vector.…”

Section: Methodsmentioning

confidence: 99%

Analysing Powder Injection Moulding of a Helix Geometry Using Soft Tooling

et al. 2021

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Freeform injection moulding is a novel technology for powder injection moulding where a sacrificial 3D printed mould (i.e., a soft tooling) is used as an insert in the injection process. The use of 3D printed moulds enable a higher geometrical design flexibility as compared to the conventional injection moulding process. However, there is still very limited knowledge on how the sacrificial soft tooling material and powder suspension handles the increased geometrical complexity during the process. In this study, a stainless steel powder suspension is injected into a geometrically challenging sacrificial mould (viz. a helix structure) that is produced by vat photopolymerization additive manufacturing. Computed tomography is used to quantify the geometrical precision of the mould both before and after injection. In addition, a new numerical model that considers the suspension feedstock is developed to investigate the powder injection moulding process. The numerical results are found to be in qualitative good agreement with the experimental findings in terms of pinpointing critical areas of the structure, thereby highlighting a new pathway for evaluating sacrificial inserts for powder injection moulding with a high geometrical complexity.

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Injection molding and shear‐induced stress simulation of poly (styrene‐ethylene‐butylene‐styrene) and polypropylene blends

Chen

Yang

et al. 2022

J of Applied Polymer Sci

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In this article, the structure and rheological properties of poly (styrene‐ethylene‐butylene‐styrene) (SEBS) triblock copolymer blends are analyzed. The influence of polypropylene content on the three SEBS blends was discussed, the viscoelastic response and phase structure evolution during injection molding were studied. According to the capillary flow test data, the least square method is used to fit the viscosity parameters of the cross‐WLF model. The filling length of the spline was tested by adjusting the injection molding process parameters, and its accuracy was verified by comparing the filling simulation with the experimental results. Numerical simulation is used to predict the shear rate distribution of injection‐molded samples, and the shear sensitivity and residual stress of SEBS blends with different phase structures are analyzed. Based on the phase structure analysis and rheological properties, this article predicts the filling properties of triblock copolymer composites, which can be used to construct the flow‐induced structure–property relationship of complex polymer blends.

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Numerical simulation and experimental investigation of mold filling and segregation in low-pressure powder injection molding of metallic feedstock

Cited by 17 publications

References 21 publications

Research Progress on Low-Pressure Powder Injection Molding

Research Progress on Low-Pressure Powder Injection Molding

Analysing Powder Injection Moulding of a Helix Geometry Using Soft Tooling

Injection molding and shear‐induced stress simulation of poly (styrene‐ethylene‐butylene‐styrene) and polypropylene blends

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