Characterization of Polymers for Fine Processing. II. Numerical Analyses and Experimental Results of the Injection-Compression Molding.

Shiraishi, Yasuyuki; Narazaki, Norio

doi:10.1295/koron.53.381

Cited by 3 publications

(1 citation statement)

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“…Later, analysis was emphasized on the post®lling stage of the process that affects the quality of the molded parts signi®cantly [4 to 9]. In the ICM process, simulation and experimental results were reported by Shiraishi and Narazaki [10]. In this study, a simulation model was developed to predict the injection¯ow front advancement as well as variations of the pressure, temperature, and shrinkage during the ®lling and compression stages.…”

Section: Introductionmentioning

confidence: 99%

Filling and Postfilling Analysis of Injection/Compression Molding

Young

2000

International Polymer Processing

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Injection compression molding is a process that modi®es the original injection molding process to have a compression stage after the injection. This process is suitable for precision injection molding parts. The success of an injection compression molding process relies on proper design of the mold and selection of process conditions. The main scope of this study is to develop a process simulation tool for the injection compression molding process. The simulation tool is used to predict the state variations of the material during the molding, including molding¯ow, distributions of temperature and pressure, and the material shrinkage. The effect of the compression action on the molding part was investigated by this study. The compression action can provide more uniform packing on the mold cavity. But, with the non-uniform cooling, material can have different¯uidity in the cavity, which induces pressure gradients during the compression action. From the simulation results, it is demonstrated that a twostage compression action in the injection compression molding process can reduce the pressure gradient in the cavity and still have low shrinkage. By using this method, products with higher precision and lower warpage can be molded.

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Section: Introductionmentioning

confidence: 99%

Filling and Postfilling Analysis of Injection/Compression Molding

Young

2000

International Polymer Processing

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Numerical predictions of 3‐D filler orientation and elastic compliance for reinforced plastics containing fillers with aspect ratio distribution

2004

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In the injection molding of parts containing 30 wt% short‐glass‐fiber or glass‐flake, filler orientation distribution functions and elastic constants are predicted, taking into account the aspect ratio distribution of fillers. The filler orientation distribution functions and the elastic compliance tensors are estimated by using Advani's method and Wakashima's method, respectively. The estimated filler orientation distributions in composite parts reinforced with short‐glass‐fiber or glass‐flake agree with soft X‐ray photograph observations. The fiber orientation distribution function, predicted for interaction coefficient CI = 0.01, is close to the experimental results. Based on this orientation distribution, the elastic compliance tensor distributions are predicted on the assumption that the filler aspect ratio can be presented by a circumscribed filler aspect ratio or an equivalent filler aspect ratio. As a result, the vibration behavior predicted by adopting the equivalent aspect ratio agrees with the experimental results. Polym. Compos. 25:194–213, 2004. © 2004 Society of Plastics Engineers.

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The application of an integral type constitutive equation to numerical flow analyses of viscoelastic fluid in unsteady flow

Shiraishi

Narazaki

Kikutani

2001

Polymer Engineering & Sci

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The applicability of the Wagner model to numerical flow analyses of the injection molding process is investigated under the following approximations: the strain and stress histories of the molten polymer before the injection is negligible, and the flow field in a mold cavity is treated as Hele-Shaw flow. A comparison between the results for simple step-strain-rate flow calculated with the Wagner model and that calculated with the Leonov model suggests that the Wagner model is superior to the Leonov model for unsteady flow because of its stability and accuracy. Therefore, numerical flow analysis software of a viscoelastic fluid in the injection molding process is developed using the Wagner model. For the analysis, the velocity profile of a Newtonian fluid is used instead of that obtained through iterative calculation. The validity of the developed program is confirmed through a comparison of the results of the computation for two simple flow velocity histories with the analytical results from the Wagner model. Furthermore, the computation time of the developed software is only 1.4 times greater than that of the previous numerical flow analysis of a viscous fluid.

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Characterization of Polymers for Fine Processing. II. Numerical Analyses and Experimental Results of the Injection-Compression Molding.

Cited by 3 publications

References 0 publications

Filling and Postfilling Analysis of Injection/Compression Molding

Filling and Postfilling Analysis of Injection/Compression Molding

Numerical predictions of 3‐D filler orientation and elastic compliance for reinforced plastics containing fillers with aspect ratio distribution

The application of an integral type constitutive equation to numerical flow analyses of viscoelastic fluid in unsteady flow

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