Advances in Injection Molding: Process, Materials and Applications

A special issue of Journal of Manufacturing and Materials Processing (ISSN 2504-4494).

Deadline for manuscript submissions: 1 July 2024 | Viewed by 15192

Special Issue Editors


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Guest Editor
Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing, National Research Council (STIIMA-CNR), 70124 Bari, Italy
Interests: injection molding; micro manufacturing; polymer properties and processing; composites; polymeric foams; additive manufacturing
Special Issues, Collections and Topics in MDPI journals

E-Mail Website
Guest Editor
Institute of Intelligent Industrial Technologies and Systems for Advanced Manufacturing, National Research Council (STIIMA-CNR), 70124 Bari, Italy
Interests: injection molding; rheology; surface properties; metrological characterization; FEM simulation

Special Issue Information

Dear Colleagues,

Injection molding is a well-established manufacturing technology. The exploitation of high-performance materials and the recent design of components and devices in emerging fields of application open up new scenarios. This breakthrough seems particularly applicable to micro injection molding, the interest in which is rapidly growing thanks to the worldwide increasing demand for miniaturization.

Therefore, the aim of this SI is to collect scientific contributions on the recent advances in injection molding and process/materials interactions. In particular, analyses related to the following main topics will be appreciated: the process itself (process parameters influence, optimization, process modeling, simulation, artificial intelligence), materials and novel composites to be used (how their thermal and mechanical properties are modified by the process), characterization of products (metrology, quality control, monitoring), and fields of application (component performance with a special focus on sustainable and climate-neutral approaches, health-care, communications devices, optical components).

Dr. Rossella Surace
Dr. Vincenzo Bellantone
Dr. Irene Fassi
Guest Editors

Manuscript Submission Information

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Keywords

  • injection molding
  • micro injection molding
  • materials/process interactions
  • structure/properties relationships
  • quality control

Published Papers (7 papers)

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Research

15 pages, 3569 KiB  
Article
Experimental Uncertainty Evaluation in Optical Measurements of Micro-Injection Molded Products
by Vincenzo Bellantone, Rossella Surace and Irene Fassi
J. Manuf. Mater. Process. 2024, 8(1), 21; https://doi.org/10.3390/jmmp8010021 - 26 Jan 2024
Viewed by 1125
Abstract
Optical measurements are increasingly widely used as preferential techniques to evaluate dimensional and surface quantities in micro-products. However, uncertainty estimation is more critical on micro-products than macro, and it needs careful attention for evaluating the obtained quality, the requested tolerance, and the correct [...] Read more.
Optical measurements are increasingly widely used as preferential techniques to evaluate dimensional and surface quantities in micro-products. However, uncertainty estimation is more critical on micro-products than macro, and it needs careful attention for evaluating the obtained quality, the requested tolerance, and the correct setting of experimental process settings. In this study, optical measurements characterized micro-injected products by linear and surface acquisition and considered all the sources contributing to uncertainties. The results show that the measure uncertainty could be underestimated if only the standard deviation on simple measurements is considered; this could cause a significant restriction of the estimated range covering the measured values. Furthermore, the findings confirm that the correct evaluation of the potential uncertainties contributes to accurately assessing the process behavior and improving product quality. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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16 pages, 1683 KiB  
Article
Impact of Injection Molding Parameters on Material Acoustic Parameters
by Komeil Saeedabadi, Fabian Lickert, Henrik Bruus, Guido Tosello and Matteo Calaon
J. Manuf. Mater. Process. 2023, 7(6), 222; https://doi.org/10.3390/jmmp7060222 - 06 Dec 2023
Viewed by 1498
Abstract
Understanding the relationship between injection molding parameters and the acoustic properties of polymers is crucial for optimizing the design and performance of acoustic-based polymer devices. In this work, the impact of injection molding parameters, such as the injection velocity and packing pressure, on [...] Read more.
Understanding the relationship between injection molding parameters and the acoustic properties of polymers is crucial for optimizing the design and performance of acoustic-based polymer devices. In this work, the impact of injection molding parameters, such as the injection velocity and packing pressure, on the acoustic parameters of polymers, namely the elastic moduli, is studied. The measurements lead to calculating material parameters, such as the Young’s modulus and Poisson’s ratio, that can be swiftly measured and determined thanks to this method. Polymethyl methacrylate (PMMA) was used as the molding material, and using PMMA LG IG 840, the parts were simulated and injection molded, applying a ‘design of experiment’ (DOE) statistical method. The results indicated a correlation between the injection molding process parameters and the acoustic characteristics, such as the elastic moduli, and a specifically decreasing trend with increase in the injection velocity. Notably, a relative decrease in the Young’s modulus by 1% was observed when increasing the packing pressure from 90MPa to 120MPa. Similarly, a decrease in the Poisson’s ratio of 2.9% was observed when the injection velocity was increased from 16mm/s to 40mm/s. This method can be used to fine-tune the material properties according to the needs of a given application and to facilitate the characterization of different polymer acoustic properties essential for acoustic-based polymer devices. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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22 pages, 15002 KiB  
Article
Time and Spatially Resolved Operando Small-Angle X-ray Scattering Measurements during Injection Moulding of Plastics
by Matteo Arioli, Anabela Paiva Massano, Daniel P. da Silva, Fábio A. Gameiro, Pedro Carreira, Marc Malfois, João Matias, Paula Pascoal-Faria, Artur Mateus and Geoffrey R. Mitchell
J. Manuf. Mater. Process. 2023, 7(5), 176; https://doi.org/10.3390/jmmp7050176 - 29 Sep 2023
Viewed by 2282
Abstract
We recently introduced the possibility of performing operando small-angle X-ray scattering measurements using a novel industrially relevant injection moulding system for plastics. We show that useful time-resolving measurements can be performed with a time-cycle of 1 s and highlight the possible steps to [...] Read more.
We recently introduced the possibility of performing operando small-angle X-ray scattering measurements using a novel industrially relevant injection moulding system for plastics. We show that useful time-resolving measurements can be performed with a time-cycle of 1 s and highlight the possible steps to reduce this to 0.5 s. We show how we can use the transmission measurements to provide a time marker when plastic first enters the mould cavity in the region probed by the incident X-ray beam. We show the opportunities provided by this experimental stage mounted on the NCD-SWEET beamline at ALBA to probe the reproducibility of the injection moulding system on different scales. The design of the equipment allowed for the development of the structure and the morphology to be evaluated in different parts of mould cavity, and we evaluated any differences in a rectangular mould cavity. We identified future prospects for this equipment in terms of novel mould heating and cooling systems and the opportunities for quantitatively evaluating radical approaches to injection moulding technology. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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16 pages, 3245 KiB  
Article
Evaluation of Processing Conditions in the Performance of Purging Compounds for Polypropylene Injection Molding
by Miguel Carrasco, Jorge Guerrero, Miriam Lazo, Estephany Adrián, Jorge Alberto Medina-Perilla and Andrés Rigail-Cedeño
J. Manuf. Mater. Process. 2023, 7(1), 31; https://doi.org/10.3390/jmmp7010031 - 26 Jan 2023
Cited by 1 | Viewed by 2497
Abstract
Purging is a fundamental process in the injection molding sector, aiding in color transition, material shifts, and the removal of contaminants. The purging compounds can be classified according to physical or chemical mechanisms and are affected by processing parameters, such as temperature, pressure, [...] Read more.
Purging is a fundamental process in the injection molding sector, aiding in color transition, material shifts, and the removal of contaminants. The purging compounds can be classified according to physical or chemical mechanisms and are affected by processing parameters, such as temperature, pressure, or soaking period. Despite some studies on the effect of processing parameters in purging action, an analysis of the rheological behavior and physico-chemical changes is still required for a deeper understanding of this type of system. This study explored shear viscosity, activation energy behavior in the torque rheometer, injection molding process, and energy consumption for two polyolefin-based purging compounds: one on polypropylene (PP) and another on polyethylene (PE). The results showed that the PP-based compound is a highly viscous material with low thermal sensibility and low energy consumption. The PE-based chemical compound, which includes an expanding and scrubbing agent, presented higher thermal sensitivity. Lower purging times and specific energy consumption were observed for the mechanical purge regardless of the processing temperature in the injection molding machine. However, torque and specific total mechanical energy differed due to viscosity and possible filler particle agglomeration. These findings demonstrated the influence of processing temperature on rheology and performance. Nonetheless, further studies regarding pressure, soaking time, and rheological modeling are recommended. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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11 pages, 2269 KiB  
Article
Thermal Contact Resistance between Mold Steel and Additively Manufactured Insert for Designing Conformal Channels: An Experimental Study
by Andrews Souza, Paulina Capela, Vítor Lopes, Filipe Prior, Hélder Puga, Delfim Soares and José Teixeira
J. Manuf. Mater. Process. 2022, 6(5), 99; https://doi.org/10.3390/jmmp6050099 - 13 Sep 2022
Cited by 4 | Viewed by 2229
Abstract
The focus of this research is on thermal contact resistance between a mold and its insert, specifically inserts made by additive manufacturing (AM). Using a thermal steady-state system and varying contact pressures (0, 50, 75, and 100 bars), we present experimental results of [...] Read more.
The focus of this research is on thermal contact resistance between a mold and its insert, specifically inserts made by additive manufacturing (AM). Using a thermal steady-state system and varying contact pressures (0, 50, 75, and 100 bars), we present experimental results of the thermal contact resistance at the contact interface between steel A (1.2344), obtained from an extruded rod, and steel B (1.2709), produced by laser powder bed fusion. Thermal tests were performed for unbonded and bonded configurations. Results showed that increasing the contact pressure allows the system equilibrium to be reached at lower temperatures. Furthermore, thermal tests showed that in the transition zone of the bonded configuration, a well-defined resistance is not formed between the two steel samples as it occurs in the unbonded configuration. For the unbonded configuration, the thermal contact resistance values decrease with increasing applied contact pressure, improving the system’s heat transfer. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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13 pages, 11362 KiB  
Article
Development and Production of Artificial Test Swarf to Examine Wear Behavior of Running Engine Components—Geometrically Derived Designs
by Patrick Brag, Volker Piotter, Klaus Plewa, Alexander Klein, Mirko Herzfeldt and Sascha Umbach
J. Manuf. Mater. Process. 2022, 6(5), 100; https://doi.org/10.3390/jmmp6050100 - 13 Sep 2022
Cited by 2 | Viewed by 1506
Abstract
Subtractive manufacturing processes are usually accompanied by the occurrence of tiny flakes and swarf, which later on cause severe wear and damage, especially in moving components such as rolling or sliding bearings, pistons, etc. However, up until now, such detrimental effects have hardly [...] Read more.
Subtractive manufacturing processes are usually accompanied by the occurrence of tiny flakes and swarf, which later on cause severe wear and damage, especially in moving components such as rolling or sliding bearings, pistons, etc. However, up until now, such detrimental effects have hardly been investigated. One reason is the lack of a definition of a typical design of debris particle. Therefore, the main goal of the project described in this paper was to elaborate a draft that defines standardized test particles. It had to be evaluated whether test particles could be adequately reproduced and whether they would reveal significant damage potential. Taking into account future mass fabrication, Micro Powder Injection Molding (MicroPIM) was chosen as a production method. Five different 3D designs of geometrically defined test particles were developed. The maximum size of each design was 1167 mm in green state; however, all samples shrank in size during sintering. Specially tailored feedstocks containing 42CrMo4 steel powders were used and the related molding, debinding and sintering procedures were developed. All particle geometries and related mold inserts were developed using a commercial software routine for the layout of runner systems, gate locations and ejector positions. The damage potential of the test particles was evaluated based on trials using journal bearing and shift valve test rigs. Although only a moderate degree of damage potential could be ascertained up until now, it can be expected that the artificial swarf will enable standardized wear test procedures to be developed. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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12 pages, 3202 KiB  
Article
Crystallization and Aging Behavior of Polyetheretherketone PEEK within Rapid Tooling and Rubber Molding
by Karim Abbas, Nicolae Balc, Sebastian Bremen and Marco Skupin
J. Manuf. Mater. Process. 2022, 6(5), 93; https://doi.org/10.3390/jmmp6050093 - 26 Aug 2022
Cited by 3 | Viewed by 2858
Abstract
In times of short product life cycles, additive manufacturing and rapid tooling are important methods to make tool development and manufacturing more efficient. High-performance polymers are the key to mold production for prototypes and small series. However, the high temperatures during vulcanization injection [...] Read more.
In times of short product life cycles, additive manufacturing and rapid tooling are important methods to make tool development and manufacturing more efficient. High-performance polymers are the key to mold production for prototypes and small series. However, the high temperatures during vulcanization injection molding cause thermal aging and can impair service life. The extent to which the thermal stress over the entire process chain stresses the material and whether it leads to irreversible material aging is evaluated. To this end, a mold made of PEEK is fabricated using fused filament fabrication and examined for its potential application. The mold is heated to 200 °C, filled with rubber, and cured. A differential scanning calorimetry analysis of each process step illustrates the crystallization behavior and first indicates the material resistance. It shows distinct cold crystallization regions at a build chamber temperature of 90 °C. At an ambient temperature above Tg, crystallization of 30% is achieved, and cold crystallization no longer occurs. Additional tensile tests show a decrease in tensile strength after ten days of thermal aging. The steady decrease in recrystallization temperature indicates degradation of the additives. However, the tensile tests reveal steady embrittlement of the material due to increasing crosslinking. Full article
(This article belongs to the Special Issue Advances in Injection Molding: Process, Materials and Applications)
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