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Polymers and Injection Molding Simulation
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Polymers and Injection Molding Simulation

A special issue of Materials (ISSN 1996-1944). This special issue belongs to the section "Materials Chemistry".

Deadline for manuscript submissions: closed (30 September 2021) | Viewed by 11111

Special Issue Editor

Prof. Dr. Mónica S. A. Oliveira

E-Mail Website
Guest Editor
Centre of Mechanical Technology and Automation, Department of Mechanical Engineering, University of Aveiro, Aveiro, Portugal
Interests: polymer processing; polymer flow numerical simulation; material characterization; nanocomposites
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The molds and plastics industry, like so many other industrial sectors, has farced enormous challenges in a bid to increase competitiveness through the search for a cleaner, less energy-intensive production that makes better use of material resources.

The consumption of polymers throughout the world is continuously increasing, and as new materials are being sought to meet consumer requirements and specifications, innovative ways are being envisaged to fully comprehend plastic waste recycling in an effort to promote a circular economy. It is a fact that new polymers or polymer-based materials require a comprehensive thermophysical and rheological characterization prior to any process numerical simulation when their application is being analyzed. When it comes to polymeric materials recovered from waste, such assessement is paramount, since recyclates from post-consumer waste are subjected to environmental weathering, physical and chemical alterations induced by service life, and pollution and contaminants that may contribute to downgrading the material properties. Moreover, a synergetic interaction between the injection molding/rheological simulation (using properly characterized material models) and their application suitability is fundamental for a wide acceptance of waste-plastic-recycled polymers.

Numerical simulation of injection molding is a powerful tool to be used in the early stages of the process to optimize the design of parts for manufacture, validate and improve the injection mold tool design, trouble shoot molding problems, and reduce cost and lead time to market. Moreover, proper attention must be paid to the different control strategies that may be envisaged during mold production. Highly complex parts are continuously being sought, and with the rapid advance of additive technologies, the use of strategies such as conformal cooling to enhance heat dissipation and improve overall cycle time are also being assessed. It is, therefore, of utmost importance to establish new trends in what concerns mold diagnosis for part quality assessment.

These are a few trends for increasing the competitiveness of an industrial sector that is highly innovative, but which has important goals and is rapidly evolving.

It is my pleasure to invite you to submit a manuscript to this Special Issue. Full papers, communications, and reviews are all welcome.

Assist. Prof. Mónica S. A. Oliveira
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

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. Materials 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 2600 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
  • polymer flow numerical simulation
  • polymer characterization
  • nanocomposites
  • ecodesign and ecoefficiency
  • circular economy
  • plastic waste recycling
  • CAE

Published Papers (5 papers)

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Research

15 pages, 3261 KiB  
Article
Design and Simulation Study of the Induction Heated Injection Mold with Sliders
by Paweł Muszyński, Przemysław Poszwa, Krzysztof Mrozek, Michał Zielinski, Piotr Dalewski and Michał Kowal
Materials 2021, 14(23), 7476; https://doi.org/10.3390/ma14237476 - 06 Dec 2021
Cited by 1 | Viewed by 2296
Abstract
In order to increase the quality of the products manufactured by injection molding, RTC technology can be used to achieve higher mold temperatures. As a result, the path of the injected melt can be extended, allowing the production of parts with more complex [...] Read more.
In order to increase the quality of the products manufactured by injection molding, RTC technology can be used to achieve higher mold temperatures. As a result, the path of the injected melt can be extended, allowing the production of parts with more complex shapes and greater length. Induction heating allows heating only selected forming surfaces of the mold which increases the speed and efficiency of the process. This paper presents the concept of a detachable inductor integrated with sliders to enable the application of this technology in an injection mold with sliders, along with the theoretical model used to perform the tests. First, the effect of the magnetic concentrator shape on the process was analyzed. This was followed by a simulation study of the influence of process parameters: heating time, frequency, and electric current. An extensive analysis of the test results of the temperature distribution on the insert allowed for the selection of parameter sets that would enable obtaining the desired surface temperature without a major increase in process time. The results of simulation studies confirm the possible applications and present the range of parameters for obtaining the optimal process. Full article
(This article belongs to the Special Issue Polymers and Injection Molding Simulation)
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17 pages, 11471 KiB  
Article
Computer-Aided Reengineering towards Plastic Part Failure Minimization
by Tiago Pinho, Tatiana Zhiltsova, Mónica Oliveira and Andreia Costa
Materials 2021, 14(21), 6303; https://doi.org/10.3390/ma14216303 - 22 Oct 2021
Cited by 4 | Viewed by 1260
Abstract
The work reported here intends to identify and mitigate the causes for failure in a plastic faucet holder, a part of an integral float faucet with a well-documented history of fracture occurrence. A methodology for the identification of hidden internal defects in plastic [...] Read more.
The work reported here intends to identify and mitigate the causes for failure in a plastic faucet holder, a part of an integral float faucet with a well-documented history of fracture occurrence. A methodology for the identification of hidden internal defects in plastic parts and the elaboration of the required corrective actions towards quality improvement is, therefore, presented. Firstly, part defects were identified via injection moulding process numerical simulation. The latter has enabled the prediction of an excessive volumetric shrinkage at the core of the faucet holder, highlighting the presence of internal voids and, hence, the possible deterioration of the load-bearing capacity. The supposition was later confirmed by X-ray topography scans. Part reengineering, consisting of localized thickness reduction, was the option chosen for decreasing the high shrinkage at the core. For validation purposes, structural analyses were carried out, with and without accounting for the injection moulding processing history. The results obtained during part structural analysis have enabled us to conclude that, when taking into account the residual stresses generated during injection moulding, the analysis more closely reflects the experimental data and allows us to implicitly envisage the propensity to fracture. Moreover, the part modifications, undertaken during the faucet holder reengineering, led to the reduction of the cumulative (processing and imposed by load) stresses by 50%, when compared to the original design analysed. Full article
(This article belongs to the Special Issue Polymers and Injection Molding Simulation)
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18 pages, 11302 KiB  
Article
Towards Enhancing the Potential of Injection Molding Tools through Optimized Close-Contour Cooling and Additive Manufacturing
by Sebastian Gries, Guillaume Meyer, Andreas Wonisch, Reinhard Jakobi and Christian Mittelstedt
Materials 2021, 14(12), 3434; https://doi.org/10.3390/ma14123434 - 21 Jun 2021
Cited by 5 | Viewed by 2280
Abstract
This work deals with the parametric optimization of the position and form of a conformal cooling used in the injection molding industry. Based on a literature survey, an optimization routine concerning the parameter optimization of cooling system designs was developed and implemented with [...] Read more.
This work deals with the parametric optimization of the position and form of a conformal cooling used in the injection molding industry. Based on a literature survey, an optimization routine concerning the parameter optimization of cooling system designs was developed and implemented with the help of the software package Moldflow. The main objective of the optimization is to reduce the cooling time; the second is to obtain an optimized homogeneous temperature distribution over the complete tool surface. To enable a comparison of the new close-contour solution with a classical manufacturing process, an optimized cooling system simulation, based on a conventional manufacturing solution, was established. It can be shown that the optimized close-contour cooling design offers significant advantages that cannot be exploited using classical manufacturing. Finally, the additive manufacturing of a prototype in the framework of powder bed fusion is documented as a proof of concept. Full article
(This article belongs to the Special Issue Polymers and Injection Molding Simulation)
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13 pages, 52545 KiB  
Article
Application of Selective Induction Heating for Improvement of Mechanical Properties of Elastic Hinges
by Paweł Muszyński, Przemysław Poszwa, Andrzej Gessner and Krzysztof Mrozek
Materials 2021, 14(10), 2543; https://doi.org/10.3390/ma14102543 - 13 May 2021
Cited by 6 | Viewed by 1507
Abstract
Injection molding is a polymer processing technology used for manufacturing parts with elastic hinges. Elastic hinges are widely used in FMCG (Fast Moving Consumer Goods) packaging (e.g., bottle closures of shampoos, sauces) and in the electrical engineering industry. Elastic hinge is a thin [...] Read more.
Injection molding is a polymer processing technology used for manufacturing parts with elastic hinges. Elastic hinges are widely used in FMCG (Fast Moving Consumer Goods) packaging (e.g., bottle closures of shampoos, sauces) and in the electrical engineering industry. Elastic hinge is a thin film that connect two regions of the injection molded part, where significant shear rates are present, which can lead to the degradation of polymers and the decrease in mechanical properties. Selective induction heating is the method that improves the flow of the polymer melt through thin regions by the local increase in mold temperature. In this study, selective induction heating was used to improve mechanical properties of elastic hinges by the reduction of material degradation due to high shear rates. To verify the change of shear rates, selective induction heating simulation and injection molding simulations were performed. The linear relation between mold temperature and maximum shear rate in the cross-section was identified and the mechanical tests showed significant differences in hinge stiffness, tensile strength and elongation at break. Full article
(This article belongs to the Special Issue Polymers and Injection Molding Simulation)
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27 pages, 16047 KiB  
Article
Study on External Gas-Assisted Mold Temperature Control with the Assistance of a Flow Focusing Device in the Injection Molding Process
by Nguyen Truong Giang, Pham Son Minh, Tran Anh Son, Tran Minh The Uyen, Thanh-Hai Nguyen and Hung-Son Dang
Materials 2021, 14(4), 965; https://doi.org/10.3390/ma14040965 - 18 Feb 2021
Cited by 14 | Viewed by 2627
Abstract
In the injection molding field, the flow of plastic material is one of the most important issues, especially regarding the ability of melted plastic to fill the thin walls of products. To improve the melt flow length, a high mold temperature was applied [...] Read more.
In the injection molding field, the flow of plastic material is one of the most important issues, especially regarding the ability of melted plastic to fill the thin walls of products. To improve the melt flow length, a high mold temperature was applied with pre-heating of the cavity surface. In this paper, we present our research on the injection molding process with pre-heating by external gas-assisted mold temperature control. After this, we observed an improvement in the melt flow length into thin-walled products due to the high mold temperature during the filling step. In addition, to develop the heating efficiency, a flow focusing device (FFD) was applied and verified. The simulations and experiments were carried out within an air temperature of 400 °C and heating time of 20 s to investigate a flow focusing device to assist with external gas-assisted mold temperature control (Ex-GMTC), with the application of various FFD types for the temperature distribution of the insert plate. The heating process was applied for a simple insert model with dimensions of 50 mm × 50 mm × 2 mm, in order to verify the influence of the FFD geometry on the heating result. After that, Ex-GMTC with the assistance of FFD was carried out for a mold-reading process, and the FFD influence was estimated by the mold heating result and the improvement of the melt flow length using acrylonitrile butadiene styrene (ABS). The results show that the air sprue gap (h) significantly affects the temperature of the insert and an air sprue gap of 3 mm gives the best heating rate, with the highest temperature being 321.2 °C. Likewise, the actual results show that the height of the flow focusing device (V) also influences the temperature of the insert plate and that a 5 mm high FFD gives the best results with a maximum temperature of 332.3 °C. Moreover, the heating efficiency when using FFD is always higher than without FFD. After examining the effect of FFD, its application was considered, in order to improve the melt flow length in injection molding, which increased from 38.6 to 170 mm, while the balance of the melt filling was also clearly improved. Full article
(This article belongs to the Special Issue Polymers and Injection Molding Simulation)
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