Toward a viscoelastic modeling of anisotropic shrinkage in injection molding of amorphous polymers

Kwon, Keehae; Isayev, A. I.; Kim, K. H.

doi:10.1002/app.22399

Cited by 25 publications

(13 citation statements)

References 24 publications

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“…It is also of interest to evaluate the shrinkage (more precisely the strain) in the thickness direction which is known to be larger than that in the lateral direction in general. In the present study the thickness shrinkage is calculated following the volumetric shrinkage approach [36][37][38] with the help of the concept of mass conservation. In other words, it is determined from the conservation of mass between the end of the packing stage and the equilibrium state [37].…”

Section: Determination Of Final Thickness Shrinkagementioning

confidence: 99%

Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. I. Development of lateral motion modeling

Yang

Kwon

2008

Polymer Engineering & Sci

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The present study aims at improving the state of art physical modeling in the numerical simulation for a precision injection molding to take into account the shrinkage behavior observed by experimental measurements. In Part I, new lateral motion models have been developed to predict the birefringence, residual stress profiles, and effects of various processing conditions on the shrinkage altogether. In conventional models, the lateral motion is either allowed too early or totally prohibited in the cooling stage. With the new modeling, more general description of lateral motion has been achieved either by allowing the lateral motion if an averaged lateral residual stress reaches a certain value or by letting the lateral motion develop continuously when a shearing strength is equal to an estimated shear stress. POLYM. ENG. SCI., 2008. © 2008 Society of Plastics Engineers

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Section: Determination Of Final Thickness Shrinkagementioning

confidence: 99%

Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. I. Development of lateral motion modeling

Yang

Kwon

2008

Polymer Engineering & Sci

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“…Araújo et al [3] described the development of a parallel threedimensional unstructured nonisothermal flow solver for the simulation of the injection molding process. Kwon et al [4] proposed a novel approach to predict anisotropic shrinkage of amorphous polymers in injection moldings based on PVT equation of state, frozen-in molecular orientation, and elastic recovery. Yang et al [5] proposed a numerical simulation algorithm for the complicated filling process with edge effect in the process of resin transfer molding.…”

Section: Introductionmentioning

confidence: 99%

Energy-Efficient Enhancement for Viscoelastic Injection Rheomolding Using Hierarchy Orthogonal Optimization

Wang

Zhang

2018

Mathematical Problems in Engineering

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The viscoelastic injection molding involves multidisciplinary thermoplastic rheomolding parameters which is a complex mathematical problem. Particularly for rheomolding of complex parts with thin-walled structure, boss, and grooves, the increasing higher requirements on energy efficiency and rheomolding quality are put forward. Therefore, an energy-efficient enhancement method for viscoelastic injection molding using hierarchy orthogonal optimization (HOO) is proposed. Based on the thermoplastic rheomolding theory and considering the viscoelastic effects in injection molding, a set of partial differential equations (PDE) describing the physical coupling behavior of the mold-melt-injection molding machine is established. The fuzzy sliding mode control (FSMC) is used to reduce the energy consumption in the control system of the injection molding machine's clamping force. Then, the HOO model of viscoelastic injection rheomolding is built in terms of thermoplastic rheomolding parameters and injection machine parameters. In initial hierarchy, through Taguchi orthogonal experiment and Analysis of Variance (ANOVA), the amount of gate, melt temperature, mold temperature, and packing pressure are extracted as the significant influence parameters. In periodical hierarchy, the multiobjective optimization model takes the forming time, warping deformation, and energy consumption of injection molding as the multiple objectives. The NSGA-II (Nondominated Sorting Genetic Algorithm II) optimization is employed to obtain the optimal solution through the global Pareto front. In ultimate hierarchy, three candidate schemes are compared on multiple objectives to determine the final energy-efficient enhancement scheme. A typical temperature controller part is analyzed and the energy consumption of injection molding is reduced by 41.85%. Through the physical experiment of injection process, the proposed method is further verified.

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“…Another more important point to make is that although a rich literature exists on the effect of processing conditions on S&W, most of the research focuses on only one term, either shrinkage1–6, 8, 11, 13, 14, 19, 21, 23, 24, 27, 28 or warpage,7, 9, 10, 16, 17, 20, 25, 26, 29–33 or regard them as a whole entity 18. As a result, little work has been conducted on the different response of these two terms to the processing conditions.…”

Section: Introductionmentioning

confidence: 99%

A study on the distinguishing responses of shrinkage and warpage to processing conditions in injection molding

Liu

Zeng

Zhou

et al. 2011

J of Applied Polymer Sci

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A challenging task in injection molding industry is to minimize shrinkage and warpage (S&W) through optimal setting of molding conditions. In determining the relationship between molding conditions and product dimension, most existing literature considered S&W as a whole entity or focused on only one of them. The intention of this study was to distinguish these two terms, and perform a thorough analysis on the effect of operative conditions on S&W during injection molding process through a combination of experimental and numerical methods. Six process parameters with five levels were examined on a box‐shaped product, and the single factor analysis of variance (ANOVA) was adopted in identifying the significance of each variable in the experiment. Results indicated that the effect of processing conditions on shrinkage is different from that on warpage. Specifically, packing pressure affects shrinkage most while packing time is the dominant factor in determining warpage. The reaction of shrinkage to packing pressure is monotonic, whereas the plot of warpage shows a U‐shaped variation. A differential treatment of S&W can therefore help to enhance product quality. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

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Toward a viscoelastic modeling of anisotropic shrinkage in injection molding of amorphous polymers

Cited by 25 publications

References 24 publications

Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. I. Development of lateral motion modeling

Numerical and experimental investigation of shrinkage behavior of precision injection molded articles. I. Development of lateral motion modeling

Energy-Efficient Enhancement for Viscoelastic Injection Rheomolding Using Hierarchy Orthogonal Optimization

A study on the distinguishing responses of shrinkage and warpage to processing conditions in injection molding

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