Multi-scale filling simulation of micro-injection molding process

Choi, Sung-Joo; Kim, Sun Kyoung

doi:10.1007/s12206-010-1025-9

Cited by 41 publications

(33 citation statements)

References 17 publications

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“…Moreover, recent CAE tools allow convenient interfaces to user codes that facilitate realizing user material models and boundary conditions [71]. However, a better understanding of the heat transfer phenomena in micro-scale is necessary for predicting the phase change and morphology evolution during the melts fill into the cavity.…”

Section: Simulationmentioning

confidence: 99%

The Micro Injection Moulding Process for Polymeric Components Manufacturing

Surace¹,

Trotta²,

Bellantone³

et al. 2012

New Technologies - Trends, Innovations and Research

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Section: Simulationmentioning

confidence: 99%

The Micro Injection Moulding Process for Polymeric Components Manufacturing

Surace¹,

Trotta²,

Bellantone³

et al. 2012

New Technologies - Trends, Innovations and Research

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“…Their claims seem to be somewhat inaccurate since the material solidification phase is not included. Furthermore, the surface tension cannot actually be ignored in a micro‐scale dynamic flow calculation, because of the influencing capillary effects . Considering those restrictions, developing homemade numerical code is of a great interest to describe accurately the flow within the microscale level.…”

Section: Introductionmentioning

confidence: 99%

“…As it is a biphasic flow between two fluids (polymer melt and air), the flow front tracking of the molten polymer is simulated using the level set method (LSM) which has the advantage of representing the curvature of the molten polymer meticulously as reported by Choi et al Therefore, the motion of the interface is described for incompressible flow by the following equation which takes into account the problem of mass loss during the front advancement:

\frac{\partial ϕ}{\partial t} + u . \nabla ϕ = 0

where, u and ϕ are respectively the velocity field of the interface and the variable that describes the motion. When ( ϕ > 0), the region is filled with the polymer melt, and for ( ϕ ˂ 0) it is filled with air while ( ϕ = 0) defines the interface between the two fluids.…”

Section: Introductionmentioning

confidence: 99%

“…The surface tension represents a significant challenge in microinjection molding simulation, it was concluded in several studies its incontestable effect on the melt/air curvature advancement . Herein, the surface tension f ST in (Eqn 4) is represented as a body force which is considered proportional to the curvature of the interface (polymer‐air) K(ϕ) according to Brackbill et al It is given by the following expression:

{\overset{false\to}{f}}_{ST} = - σ K ((), ϕ) \nabla H_{ε} ((), ϕ) = - σ K ((), ϕ) \nabla ϕ . \overset{n}{true}

…”

Section: Introductionmentioning

confidence: 99%

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Simulation of crystallization evolution of polyoxymethylene during microinjection molding cycle

Benayad

Boutaous

Otmani

et al. 2019

Polymers for Advanced Techs

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A mathematical model coupled with a numerical investigation of the evolving material properties due to thermal and flow effects and in particular the evolution of the crystallinity during the full microinjection molding cycle of poly (oxymethylene) POM is presented using a multi‐scale approach. A parametric analysis is performed, including all the steps of the process using an asymmetrical stepped contracting part. The velocity and temperature fields are discussed. A parabolic distribution of the velocity across the part thickness, and a temperature rise in the thin zone toward the wall have been obtained. It is attributed to the viscous energy dissipation during the filling phase, but also to the involved characteristic times for the thermal behavior of the material. Depending on the molding conditions and the locations within the micro‐part, different evolution of crystallization rates are obtained leading to at least three to five morphological layers, obtained in the same part configuration of a previously work, allowing a clear understanding of the process‐material interaction.

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“…Therefore, many microsystem technology‐related products, such as micropumps, microgears, optical grating elements, and microheat exchangers, are widely used in many industrial fields . During μIM, the interfacial effects of wall slip and surface tension become more pronounced as compared with that of conventional injection molding (CIM) . The μIM of polymers requires extremely high injection velocity, high mold temperature, and high melt temperature to prevent premature freezing or the occurrence of short shots.…”

Section: Introductionmentioning

confidence: 99%

Role of dicumyl peroxide on the morphology and mechanical performance of polypropylene random copolymer in microinjection molding

Yang

Kong

et al. 2017

Polymers for Advanced Techs

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The purpose of this work is to systematically investigate the effects of dicumyl peroxide (DCP) on the microstructural evolution and mechanical properties of polypropylene random copolymers (PPRs) during the microinjection process. Polarized light microscopy, differential scanning calorimetry, X-ray diffraction, and scanning electronic microscopy measurements were employed to characterize the morphology evolution of the PPR microparts with DCP. A hierarchical structure was found in the PPR microparts with DCP. Specifically, with the individual addition of organic peroxide, the orientation parameter of the PPR microparts decreased pronouncedly and the formation of skin layer was suppressed, while the formation of core layer was promoted.This was ascribed to the distribution of shear rate in the microchannel, which was determined by the wall ship effect in the filling stage and the relaxation behavior in the cooling stage. A mechanism was proposed to explain the distinctive filling behavior and molding characteristics of PPR with DCP in microinjection molding. Microinjection molding possesses many advantages, such as high precision, low cost, and high productivity. Therefore, many microsystem technology-related products, such as micropumps, microgears, optical grating elements, and microheat exchangers, are widely used in many industrial fields. 2,3 During μIM, the interfacial effects of wall slip and surface tension become more pronounced as compared with that of conventional injection molding (CIM). 4The μIM of polymers requires extremely high injection velocity, high mold temperature, and high melt temperature to prevent premature freezing or the occurrence of short shots. Therefore, under such a stringent condition, high shear stress is inevitably produced in the micromold cavities. 5 When the wall shear stress exceeds the critical stress (σ c1 ), the melts slip over the solid surfaces of the microchannel upon which the phenomenon of wall slip occurs. 2The resulting interfacial effects on the morphology and properties of polymers in μIM have since attracted the intense attention of many researchers.Crystalline polymers in microchannels, such as polypropylene, exhibit hierarchical structures and mechanical properties that are strongly dependent on the temperature, velocity profile, and shear stress during the μIM. Chains subjected to a higher shear rate and higher shear stress generally induce the formation of either highly oriented or parallel lamellar stack structures. 6,7 On the contrary, chains with lower shear rates and lower shear stresses induce the formation of a spherulitic structure. The distribution of oriented structures greatly influences the hierarchical Until now, the application of polypropylene resins in microinjection production is limited due to the extremely severe molding condition. A "controlled-rheology polypropylene" technology provides an approach to improve the processing ability of polypropylene resin in μIM, which is performed using a peroxide-initiated scission (β-scission) reactio...

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Multi-scale filling simulation of micro-injection molding process

Cited by 41 publications

References 17 publications

The Micro Injection Moulding Process for Polymeric Components Manufacturing

The Micro Injection Moulding Process for Polymeric Components Manufacturing

Simulation of crystallization evolution of polyoxymethylene during microinjection molding cycle

Role of dicumyl peroxide on the morphology and mechanical performance of polypropylene random copolymer in microinjection molding

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