Preparation of Microcellular Injection-Molded Foams Using Different Types of Low-Pressure Gases via a New Foam Injection Molding Technology

2019 ◽  
Vol 58 (38) ◽  
pp. 17824-17832 ◽  
Author(s):  
Long Wang ◽  
Yuma Wakatsuki ◽  
Yuta Hikima ◽  
Masahiro Ohshima ◽  
Atsushi Yusa ◽  
...  
Keyword(s):  
Injection Molding ◽  
Low Pressure ◽  
Different Types ◽  
Injection Molded ◽  
Foam Injection Molding

A New Dewaxing Method and its Effect on the Properties of Low-Pressure Injection Molded Ceramics

2007 ◽  
Vol 336-338 ◽  
pp. 1012-1016
Author(s):  
Yin Wu ◽  
Wen Jie Si ◽  
He Zhuo Miao
Keyword(s):  
Carbon Dioxide ◽  
Injection Molding ◽  
Bending Strength ◽  
Low Pressure ◽  
Supercritical Extraction ◽  
Paraffin Wax ◽  
Organic Additives ◽  
Extraction Condition ◽  
Pressure Injection ◽  
Injection Molded

A new dewaxing method for low-pressure injection molded ceramics is presented. Supercritical extraction with carbon dioxide was used to remove paraffin wax from the ceramic green parts. The composition of organic additives for low-pressure injection molding feedstock and the extraction condition for the green parts were investigated. Moreover, the properties of sintered ceramic samples dewaxed by supercritical carbon dioxide were compared with those by thermal dewaxing. The results show that the new binder system containing 50wt% paraffin wax, 35% bee wax and 15% stearic acid fulfills the requirements of both low-pressure injection molding feedstocks and supercritical dewaxing, where the feedstock has high fluidity, low viscosity and quick solidification. The efficient extraction condition for supercritical dewaxing from the green parts is at 30MPa pressure and 45°C. Under this condition, defect free ceramic green parts can be obtained. Dewaxing methods have significant influence on the properties of sintered parts. The mechanical properties of the sintered sample can be improved by supercritical dewaxing. With this method, the bending strength of sintered samples (σ = 331.6 MPa) is higher than that obtained by thermal treatment (σ = 312.3MPa). The sintered samples dewaxed by supercritical CO2 have shown the property of higher density and less distortion compared to the thermal dewaxing method. Moreover, with supercritical extraction the dewaxing time can be reduced to about one tenth of the time required by thermal dewaxing.

scholarly journals A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Polymers ◽  
2019 ◽  
Vol 11 (11) ◽  
pp. 1896 ◽  
Author(s):  
Llewelyn ◽  
Rees ◽  
Griffiths ◽  
Jacobi
Keyword(s):  
Injection Molding ◽  
Mechanical Characteristics ◽  
Low Pressure ◽  
Microcellular Foam ◽  
Foaming Agents ◽  
Blowing Agent ◽  
Weight Saving ◽  
Microcellular Foams ◽  
Foam Injection Molding ◽  
Foam Production

Unfilled and talc-filled Copolymer Polypropylene (PP) samples were produced through low-pressure foam-injection molding (FIM). The foaming stage of the process has been facilitated through a chemical blowing agent (C6H7NaO7 and CaCO3 mixture), a physical blowing agent (supercritical N2) and a novel hybrid foaming (combination of said chemical and physical foaming agents). Three weight-saving levels were produced with the varying foaming methods and compared to conventional injection molding. The unfilled PP foams produced through chemical blowing agent exhibited the strongest mechanical characteristics due to larger skin wall thicknesses, while the weakest were that of the talc-filled PP through the hybrid foaming technique. However, the hybrid foaming produced superior microcellular foams for both PPs due to calcium carbonate (CaCO3) enhancing the nucleation phase.

Injection-molded microcellular PLA/graphite nanocomposites with dramatically enhanced mechanical and electrical properties for ultra-efficient EMI shielding applications

2018 ◽  
Vol 6 (25) ◽  
pp. 6847-6859 ◽  
Author(s):  
Guilong Wang ◽  
Guoqun Zhao ◽  
Sai Wang ◽  
Lei Zhang ◽  
Chul B. Park
Keyword(s):  
Electrical Properties ◽  
Injection Molding ◽  
Emi Shielding ◽  
Mechanical And Electrical Properties ◽  
Injection Molded ◽  
Foam Injection Molding ◽  
Graphite Nanocomposites

Lightweight and strong microcellular PLA/graphite nanocomposites with ultra-efficient EMI shielding performance were prepared using mold-opening foam injection molding.

scholarly journals Shrinkage and Warpage Minimization of Glass-Fiber-Reinforced Polyamide 6 Parts by Microcellular Foam Injection Molding

Polymers ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 889 ◽  
Author(s):  
Youngjae Ryu ◽  
Joo Seong Sohn ◽  
Chang-Seok Yun ◽  
Sung Woon Cha
Keyword(s):  
Injection Molding ◽  
Polyamide 6 ◽  
Injection Molding Process ◽  
Microcellular Foam ◽  
Molding Process ◽  
Glass Fiber Reinforced ◽  
Molded Parts ◽  
Injection Molded ◽  
Process Factors ◽  
Foam Injection Molding

Shrinkage and warpage of injection-molded parts can be minimized by applying microcellular foaming technology to the injection molding process. However, unlike the conventional injection molding process, the optimal conditions of the microcellular foam injection molding process are elusive because of core differences such as gas injection. Therefore, this study aims to derive process conditions to minimize the shrinkage and warpage of microcellular foam injection-molded parts made of glass fiber reinforced polyamide 6 (PA6/GF). Process factors and levels were first determined, with experiments planned accordingly. We simulated designed experiments using injection molding analysis software, and the results were analyzed using the Taguchi method, analysis of variance (ANOVA), and response surface methodology (RSM), with the ANOVA analysis being ultimately demonstrating the influence of the factors. We derived and verified the optimal combination of process factors and levels for minimizing both shrinkage and warpage using the Taguchi method and RSM. In addition, the mechanical properties and cell morphology of PA6/GF, which change with microcellular foam injection molding, were confirmed.

scholarly journals Structural Foams of Biobased Isosorbide-Containing Copolycarbonate

2017 ◽  
Vol 2017 ◽  
pp. 1-6 ◽  
Author(s):  
Stefan Zepnik ◽  
Daniel Sander ◽  
Stephan Kabasci ◽  
Christian Hopmann
Keyword(s):  
Injection Molding ◽  
Weight Reduction ◽  
Polymer Processing ◽  
Foam Core ◽  
Processing Technologies ◽  
Blowing Agent ◽  
Foam Properties ◽  
Injection Molded ◽  
Foam Injection Molding ◽  
Structural Foams

Isosorbide-containing copolycarbonate (Bio-PC) is a partly biobased alternative to conventional bisphenol A (BPA) based polycarbonate (PC). Conventional PC is widely used in polymer processing technologies including thermoplastic foaming such as foam injection molding. At present, no detailed data is available concerning the foam injection molding behavior and foam properties of Bio-PC. This contribution provides first results on injection-molded foams based on isosorbide-containing PC. The structural foams were produced by using an endothermic chemical blowing agent (CBA) masterbatch and the low pressure foam injection molding method. The influence of weight reduction and blowing agent concentration on general foam properties such as density, morphology, and mechanical properties was studied. The test specimens consist of a foam core in the center and compact symmetrical shell layers on the sides. The thickness of the foam core increases with increasing weight reduction irrespective of the CBA concentration. The specific (mechanical) bending properties are significantly improved and the specific tensile properties can almost be maintained while reducing the density of the injection-molded parts.

scholarly journals Effect of Aluminum Flakes on Mechanical and Optical Properties of Foam Injection Molded Parts

Polymers ◽  
2021 ◽  
Vol 13 (17) ◽  
pp. 2930
Author(s):  
Donghwi Kim ◽  
Youngjae Ryu ◽  
Ju-Heon Lee ◽  
Sung Woon Cha
Keyword(s):  
Injection Molding ◽  
Flexural Modulus ◽  
Molding Method ◽  
Molded Parts ◽  
Injection Molded ◽  
Foam Injection Molding ◽  
Molding Methods ◽  
Plastic Products ◽  
Conventional Injection Molding

Injection research using aluminum flakes has been conducted to realize metallic textures on the surface of plastic products. Several studies have focused on the effect of the orientation and quality of the flakes when using conventional injection molding methods; however, limited studies have focused on the foam injection molding method. In this study, we examined the orientation of aluminum flakes through foam injection with an inert gas and observed the changes in texture using a spectrophotometer and a gloss meter. The mechanical properties were also studied because the rigidity of the product, which is affected by the weight reduction that occurs during foaming, is an important factor. The results demonstrate that under foam injection molding, reflectance and gloss increased by 6% and 7 GU, respectively, compared to those obtained using conventional injection molding; furthermore, impact strength and flexural modulus increased by 62% and 15%, respectively. The results of this research can be applied to incorporate esthetic improvements to products and to develop functional parts.

scholarly journals Are We Able to Print Components as Strong as Injection Molded?—Comparing the Properties of 3D Printed and Injection Molded Components Made from ABS Thermoplastic

2021 ◽  
Vol 11 (15) ◽  
pp. 6946
Author(s):  
Bartłomiej Podsiadły ◽  
Andrzej Skalski ◽  
Wiktor Rozpiórski ◽  
Marcin Słoma
Keyword(s):  
Tensile Strength ◽  
Injection Molding ◽  
Mechanical Strength ◽  
Cross Section ◽  
Fused Deposition Modeling ◽  
High Strength ◽  
Large Cross Section ◽  
Fused Deposition ◽  
Injection Molded ◽  
The Cross

In this paper, we are focusing on comparing results obtained for polymer elements manufactured with injection molding and additive manufacturing techniques. The analysis was performed for fused deposition modeling (FDM) and single screw injection molding with regards to the standards used in thermoplastics processing technology. We argue that the cross-section structure of the sample obtained via FDM is the key factor in the fabrication of high-strength components and that the dimensions of the samples have a strong influence on the mechanical properties. Large cross-section samples, 4 × 10 mm2, with three perimeter layers and 50% infill, have lower mechanical strength than injection molded reference samples—less than 60% of the strength. However, if we reduce the cross-section dimensions down to 2 × 4 mm2, the samples will be more durable, reaching up to 110% of the tensile strength observed for the injection molded samples. In the case of large cross-section samples, strength increases with the number of contour layers, leading to an increase of up to 97% of the tensile strength value for 11 perimeter layer samples. The mechanical strength of the printed components can also be improved by using lower values of the thickness of the deposited layers.

scholarly journals A Practical Numerical Approach to Characterizing Non-Linear Shrinkage and Optimizing Dimensional Deviation of Injection-Molded Small Module Plastic Gears

Polymers ◽  
2021 ◽  
Vol 13 (13) ◽  
pp. 2092
Author(s):  
Xiansong He ◽  
Wangqing Wu
Keyword(s):  
Injection Molding ◽  
High Speed ◽  
Numerical Approach ◽  
Linear Shrinkage ◽  
Influential Factor ◽  
Dimensional Deviation ◽  
Non Linear ◽  
Injection Molded ◽  
Plastic Gears ◽  
Circle Diameter

This paper was aimed at finding out the solution to the problem of insufficient dimensional accuracy caused by non-linear shrinkage deformation during injection molding of small module plastic gears. A practical numerical approach was proposed to characterize the non-linear shrinkage and optimize the dimensional deviation of the small module plastic gears. Specifically, Moldflow analysis was applied to visually simulate the shrinkage process of small module plastic gears during injection molding. A 3D shrinkage gear model was obtained and exported to compare with the designed gear model. After analyzing the non-linear shrinkage characteristics, the dimensional deviation of the addendum circle diameter and root circle diameter was investigated by orthogonal experiments. In the end, a high-speed cooling concept for the mold plate and the gear cavity was proposed to optimize the dimensional deviation. It was confirmed that the cooling rate is the most influential factor on the non-linear shrinkage of the injection-molded small module plastic gears. The dimensional deviation of the addendum circle diameter and the root circle diameter can be reduced by 22.79% and 22.99% with the proposed high-speed cooling concept, respectively.

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