3D Viscoelastic Simulation of Jetting in Injection Molding

Zhang, Shixun; Hua, Shaozhen; Cao, Wei; Min, Zhiyu; Liu, Yongzhi; Wang, Yaming; Shen, Changyu

doi:10.1002/pen.25071

Cited by 6 publications

(5 citation statements)

References 16 publications

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“…In this section, the governing equations (mass, momentum, energy, and constitutive equations) for polymer melt are discretized by the finite volume method on collocated mesh. The Equations ( 1), ( 18), (19), and ( 20) can be rewritten in the following general form 37…”

Section: Finite Volume Methodsmentioning

confidence: 99%

“…The Pom‐Pom model and Rolie‐Poly model are suitable for characterizing the rheological behaviors of branched and linear polymer melts. More and more simulation results of the filling process of injection molding based on viscoelastic constitutive equations have been reported in the last decade 13–20 …”

Section: Introductionmentioning

confidence: 99%

“…More and more simulation results of the filling process of injection molding based on viscoelastic constitutive equations have been reported in the last decade. [13][14][15][16][17][18][19][20] When polymer melt is injected into the mold in the filling stage of injection molding, polymer chains will be strongly orientated and stretched in the region near the mold walls or behind the obstacles. If the molten polymer is cooled rapidly and not has enough time to relax, part of the orientation will freeze during solidification and result in anisotropy in the optical and mechanical properties of the injection-molded articles.…”

Section: Introductionmentioning

confidence: 99%

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Macroscopic and mesoscopic simulation of polystyrene melt in the filling process of injection molding

Liu

Jiang

2023

J of Applied Polymer Sci

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In this article, a fluid flow and heat transfer model which consist of the mass, momentum, and energy conservation equations together with the level set equation and Rolie‐Poly constitution equation is proposed and applied to simulate the rheological behaviors of viscoelastic polystyrene melt in the filling process of injection molding. The macroscopic velocity, pressure, temperature, stress, and mesoscopic molecular conformation of polystyrene melt are shown and analyzed detailedly during the mold filling process. The single‐mode Rolie‐Poly model is employed to describe the stress–strain relationship of polystyrene melt, and the level set method is used to capture the evolution of melt front interface. The governing equations for polymer melt are discretized by the finite volume method on collocated mesh, and solved by the SIMPLE algorithm. Numerical simulations have been implemented based on rectangular cavities with different gate locations, and rectangular and circular inserts. Numerical results indicate that the gate locations, gate numbers, insert size and shape are major factors that affect the rheological behaviors of polystyrene melt in the filling stage of injection molding, and polymer chains experienced higher shear and extension effects in the regions near to mold walls and obstacle. In addition, the length and position of weld lines are discussed in the current study.

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Section: Finite Volume Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Macroscopic and mesoscopic simulation of polystyrene melt in the filling process of injection molding

Liu

Jiang

2023

J of Applied Polymer Sci

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“…The macroscopic simulation of injection molding has been researched and developed for decades, and many simulation methods have been proposed. The mainstream method for injection molding filling simulation is the mesh-based approaches [ 3 , 4 ]. The most popular injection molding engineering software Moldflow uses the finite element method (FEM), and Modex3D uses the finite volume method (FVM).…”

Section: Introductionmentioning

confidence: 99%

A Multiscale Simulation of Polymer Melt Injection Molding Filling Flow Using SPH Method with Slip-Link Model

Ren

et al. 2022

Polymers

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In this article, a multiscale simulation method of polymer melt injection molding filling flow is established by combining an improved smoothed particle hydrodynamics method and clustered fixed slip-link model. The proposed method is first applied to the simulation of HDPE melt in a classic Poiseuille flow case, and then two high-speed and high-viscosity injection molding flow cases in two simple long 2D rectangular cavities with and without a circular obstacle, respectively, are analyzed. For each case, the macro velocity results, and the micro average number of entanglements Zave and orientation degree S results are demonstrated and discussed, and the changing trends of Zave and S are analyzed. The results of the two injection molding cases are compared, and the influence of the obstacle on the injection flow at both the macro and micro levels is analyzed. Furthermore, based on the multiscale results, reason of some structural features and defects in injection molded products are analyzed.

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“…Though it has been reported that polymeric fluids behaved strong turbulence due to viscoelastic character [17]; moreover, Balkovsky [18] found that the turbulent effect can reach the turbulent flow with Re = 5000. Recently, Zhang [19] viscoelastic numerical simulated jetting phenomenon during injection and found elasticity had an effect on the evolution of buckling during jetting.…”

Section: Introductionmentioning

confidence: 99%

Experimental and numerical investigation of jetting phenomenon in injection molding

Hua

2020

J Braz. Soc. Mech. Sci. Eng.

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Jetting phenomenon is an injection error without thoroughly understanding by far. In this study, short shot experiments and numerical simulations were performed to investigate the trigger factor inducing jetting phenomenon in injection molding. Polycarbonate was prepared for short shot experiments that carried out in a typical end-gated rectangular mold under different injection speed, mold temperature and melt temperature. It was found that repeatability of jetting was poor and with higher melt temperature came more frequency of folding. Then, three repeatable evolutions of jetting were successfully simulated. Through analyzing the quantities during the initial stage of jetting and comparing with those in simple filling pattern, it has been numerically revealed that velocity kept constant before melt impinged on the wall opposite to gate. The pressure did not increase with the increase in melt flow length and was extremely small, which turned out jetting was not a pressuredriven flow any more. Shear rate in the initial stage of jetting was less than 10 s −1 , while shear rate in front of the pillar can be as low as 10 −4 s −1 , leading that viscosity approached zero-shear-rate viscosity and melt can be seen as a Newtonian fluid. Due to without wetting mold wall enough, friction between mold wall and melt was weak as well as the internal friction among layers of melt, which resulted in melt moving without deformation. Based on the results, a reasonable mechanism was proposed that jetting occurred for lack of shear rate. Jetting could be effectively depressed by changing the magnitude or direction of velocity, which provides a theoretical guidance for mold design and products.

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3D Viscoelastic Simulation of Jetting in Injection Molding

Cited by 6 publications

References 16 publications

Macroscopic and mesoscopic simulation of polystyrene melt in the filling process of injection molding

Macroscopic and mesoscopic simulation of polystyrene melt in the filling process of injection molding

A Multiscale Simulation of Polymer Melt Injection Molding Filling Flow Using SPH Method with Slip-Link Model

Experimental and numerical investigation of jetting phenomenon in injection molding

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