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Advances in Polymer Processing Technologies: Injection Molding

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Processing and Engineering".

Deadline for manuscript submissions: 30 December 2025 | Viewed by 1774

Special Issue Editor


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Guest Editor
Department of Mechanical Engineering, Chien-Hsin University of Science and Technology, Taoyuan 320678, Taiwan
Interests: electrical conductivities of fibers; polymers

Special Issue Information

Dear Colleagues,

With the advances in injection molding technology, several technologies, including conformal cooling channels, molding prediction and optimization, smart molding, rapid heating and cooling, polymer foaming, core back, gas counter pressure, and injection–compression molding, have been introduced to overcome the molding problem. In this Special Issue of Polymers, we will provide some leading knowledge about these techniques. Thus, we seek to spotlight findings that incorporate a wide range of topics. Research articles or reviews concerning the topic are welcome.

Prof. Dr. Shyh-Shin Hwang
Guest Editor

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • injection molding
  • foamed polymer
  • gas counter pressure
  • core back
  • smart molding
  • molding prediction and optimization
  • injection–compression molding

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Published Papers (3 papers)

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Research

17 pages, 8198 KB  
Article
Determination of Optimal Reinforcement Ratios for Injection Molded Engineering Components: A Numerical Simulation
by Fuat Tan and Oğuz Veli Satı
Polymers 2025, 17(20), 2793; https://doi.org/10.3390/polym17202793 - 19 Oct 2025
Viewed by 361
Abstract
In this work, the influence of glass fibers on the performance of the injection molding process for a PA6-based AR15/M4 grip was investigated numerically. The process was realistically modeled using Autodesk Moldflow Insight for different glass fiber percentages (0 wt%, 15 wt%, 30 [...] Read more.
In this work, the influence of glass fibers on the performance of the injection molding process for a PA6-based AR15/M4 grip was investigated numerically. The process was realistically modeled using Autodesk Moldflow Insight for different glass fiber percentages (0 wt%, 15 wt%, 30 wt%, 45 wt%). The simulation results were evaluated, including the temperature distribution, flow time, pressure drop, pumping power, volumetric shrinkage and warpage displacement. The findings indicate that, with 15 wt% glass fibers, the material exhibits the shortest fill period (0.62 s) and the lowest pressure drop (0.0061 MPa) and power consumption (0.000433 kW), indicating maximum flow efficiency. On the other hand, a 30 wt% GF setup exhibited the largest volumetric shrinkage (17.76% at most) and warpage (Y: 1.213 mm), even though it had better thermal conductivity. The 45 wt% GF material exhibited the lowest amount of shrinkage and distortion but led to a greater energy consumption compared to 30 wt% GF. Overall, the 15 wt% GF grade provided the highest average process efficiency and dimensional accuracy; therefore, it is the most appropriate grade for precision molded firearm components. Full article
(This article belongs to the Special Issue Advances in Polymer Processing Technologies: Injection Molding)
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37 pages, 28692 KB  
Article
Application of Cooling Layer and Thin Thickness Between Coolant and Cavity for Mold Temperature Control and Improving Filling Ability of Thin-Wall Injection Molding Product
by Tran Minh The Uyen, Pham Son Minh and Bui Chan Thanh
Polymers 2025, 17(19), 2658; https://doi.org/10.3390/polym17192658 - 30 Sep 2025
Cited by 1 | Viewed by 415
Abstract
Effective thermal management of molds is a governing factor of the quality and stability of the injection molding process. This study introduces and validates an integrated cooling layer within a thin-walled insert mold designed to enhance thermal control and cavity filling performance. A [...] Read more.
Effective thermal management of molds is a governing factor of the quality and stability of the injection molding process. This study introduces and validates an integrated cooling layer within a thin-walled insert mold designed to enhance thermal control and cavity filling performance. A coupled heat transfer simulation model was developed and subsequently calibrated against experimental temperature measurements. To isolate the mold’s intrinsic thermal response, temperatures were measured during distinct heating and cooling cycles, free from the perturbations of polymer melt flow. The validated mold was then installed on a Haitian MA1200 III injection molding machine to conduct molding trials under various injection pressures. A strong correlation was found between the simulation and experimental results, particularly as pressure increased, which significantly improved cavity filling and reduced the deviation between the two methods. The integrated cooling layer was shown to enhance heat dissipation, minimize thermal gradients, and promote a more uniform thermal field. This, in turn, improved filling stability, especially at moderate injection pressures. These findings provide robust quantitative data for simulation model calibration and mold design optimization, highlighting the potential of advanced cooling strategies to significantly enhance injection molding performance. Full article
(This article belongs to the Special Issue Advances in Polymer Processing Technologies: Injection Molding)
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28 pages, 4538 KB  
Article
Investigation of the Melt-Rotation Effects on Fiber Orientation Variation and Geometrical Shrinkage in FRP Injection-Molded Parts
by Jing-Kai Gao, Fang-Lin Hsieh, Min-Yuan Chien and Chao-Tsai Huang
Polymers 2025, 17(17), 2360; https://doi.org/10.3390/polym17172360 - 30 Aug 2025
Viewed by 681
Abstract
The study focuses on the asymmetric shrinkage typically occurring between the upstream and downstream regions of FRP injection-molded products, a challenge that is particularly difficult to manage and improve. Specifically, two sets of four-cavity systems in one mold were utilized as the experimental [...] Read more.
The study focuses on the asymmetric shrinkage typically occurring between the upstream and downstream regions of FRP injection-molded products, a challenge that is particularly difficult to manage and improve. Specifically, two sets of four-cavity systems in one mold were utilized as the experimental platform. One set used a balanced runner (BR) system, and the other used a non-balanced runner (NBR) system. Each cavity in the four-cavity systems contained an ASTM D638 standard specimen with dimensions of 63.5 mm × 9.53 mm × 3.5 mm. Both CAE simulation and experimental methods were applied. The results show that the filling patterns from the simulation analysis closely matched those from the experimental study for both BR and NBR systems. Furthermore, by comparing the geometric shrinkage of the injected parts, significant differences were observed in the dimensional deformation in three directions (x, y, and z) between the NBR and BR systems. Specifically, at the end of the filling region (EFR), there was no noticeable difference in shrinkage along the flow direction, but the shrinkage in the cross-flow and thickness directions was reduced in the NBR system. Additionally, for the same cavity (1C) in both BR and NBR systems, the melt-rotation effect significantly reduced shrinkage in both the cross-flow and thickness directions. These findings strongly suggest that melt rotation can effectively modify the dimensional shrinkage of injection-molded parts. Moreover, fiber orientation analyses of the 1C cavity were also performed using CAE simulation for both BR and NBR systems. The results show that in the NBR system, the melt-rotation effect substantially alters the fiber orientation. Specifically, the fiber orientation tensors in the cross-flow (A22) direction exhibit a decreasing trend. It can be speculated that the melt rotation alters the flow field, which subsequently changes the fiber orientation by reducing the flow-fiber coupling effect, thereby reducing the upstream-to-downstream asymmetry in the cross-flow direction. Through in-depth analysis, it is demonstrated that the correlation between the macroscopic geometric shrinkage and the microscopic fiber orientation changes is highly consistent. Specifically, in the EFR, ΔA22 decreased by 0.0376, improving upstream/downstream shrinkage asymmetry in the cross-flow direction (Ly). Future work will investigate alternative melt-rotation designs and the optimization of model-internal parameters in FOD prediction. Full article
(This article belongs to the Special Issue Advances in Polymer Processing Technologies: Injection Molding)
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