Formation of Microscopic Voids in Resin Transfer Molded Composites
4
Citation
0
Reference
10
Related Paper
Citation Trend
Abstract:
Performance of composite materials usually suffers from process-induced defects such as dry spots or microscopic voids. While effects of void content in molded composites have been studied extensively, knowledge of void morphology and spatial distribution of voids in composites manufactured by resin transfer molding (RTM) remains limited. In this study, through-the-thickness void distribution for a disk-shaped, E-glass/epoxy composite part manufactured by resin transfer molding is investigated. Microscopic image analysis is conducted through-the-thickness of a radial sample obtained from the molded composite disk. Voids are primarily found to concentrate within or adjacent to the fiber preforms. More than 93% of the voids are observed within the preform or in a so-called transition zone, next to a fibrous region. In addition, viod content was found to fluctuate through-the-thickness of the composite. Variation up to 17% of the average viod content of 2.15% is observed through-the-thicknesses of the eight layers studied. Microscopic analysis revealed that average size of voids near the mold surfaces is slightly larger than those located at the interior of the composite. In addition, average size of voids that are located within the fiber preform is observed to be smaller than those located in other regions of the composite. Finally, proximity to the surface is found to have no apparent effect on shape of voids within the composite.Keywords:
Transfer molding
Void (composites)
Molding (decorative)
Bolster and Stripper Assembly is used to support mold box, match plate and pattern for mold preparation with green sand in high pressure molding machine. Different types of molding machines used for preparation of mold from green sand are flask type molding machine and flask less type molding machine. Commonly used molding machine is flask type molding machine with bolster and stripper assembly for mold preparation. This paper explains design and analysis of bolster and stripper assembly for manufacturing required size mold in high pressure green sand molding machine.
Bolster
Molding (decorative)
Cite
Citations (0)
Abstract The manufacture of polymer composites through the process of resin transfer molding (RTM) involves the impregnation of the reactive polymer resing into a mold with preplaced fibrous reinforcements. Determination of RTM processing conditions requires the understanding of various parameters, such as material properties, mold geometry, and mold filling conditions. Modeling of the entire RTM process provides a tool for analyzing the relationship of the important parameters. This study developed a nonisothermal 3‐D computer simulation model for the mold filling process of RTM based on the control volume finite element method. The model will be able to simulate mold filing in molds with complicated 3‐D geometry. Results of some numerical studies in RTM show the applications of the proposed model.
Transfer molding
Molding (decorative)
Cite
Citations (79)
The Mold Cavity of the Molding tool is linked by the different curved surface smoothly and gradually .The describing methods of the surface of the mold cavity of the Molding tool have the gridding method, the algebraic method and the NURBS method. The NURBS describing method on the mold cavity of the molding tool is studied in this article, the analyse is presented.
Molding (decorative)
Cite
Citations (0)
Epoxy resin is a very important matrix resin of resin transfer molding,however,the high viscosity of epoxy resin greatly restricts its application.A preparation method of low viscosity epoxy resin system for the RTM is proposed,and the effects of its every components on the performances have been studied in detail.It is found that this modified epoxy resin system has excellent technological properties,and then the system is characterized.The relationship between its structure and performances are studied.The results show that this resin has a very good high temperature property.
Transfer molding
Gelcoat
Composite epoxy material
Molding (decorative)
Cite
Citations (0)
Recently various types of rapid mold heating/cooling technology have been developed in order to improve surface quality of products and flow ability of polymer. In this study, injection molding CAE for rapid mold heating and cooling was performed to analyze molding characteristics of the automobile band-cable. The effects of the rapid mold heating and cooling technology on the molding characteristics and pressure distribution were compared with conventional injection molding. Finally, we evaluated component technologies such as rapid mold heating and cooling system, mold materials, vacuum system through experiments to solve molding problems.
Molding (decorative)
Transfer molding
Cite
Citations (0)
The molding methods for polydimethylsiloxane(PDMS) and mold of PDMS based on microfulidic chip structure are investigated.Firstly,mold several same PDMS negative mold structures by using the same microfluidic chip.Then,sputter different thickness and types of metals on the PDMS negative mold structures,and then mold on it.Finally the structure of the secondary mold surface adhesion,structural integrity and size are investigated to determine the optimal metal and thickness.The PDMS microfluidic structural integrity is good by means of this method.This is not only a new method for PDMS molding,but also a novel solution to the mutual adhesion between PDMS and the PDMS mold and structural tear while molding directly and provides a good reference for which can not mold to get the structure of complex microfluidic chips.
Polydimethylsiloxane
Molding (decorative)
Microfluidic chip
Cite
Citations (1)
ABSTRACT High speed injection has been widely used in resin transfer molding (RTM), which improves manufacturing efficiency. This sometimes leads to excessive pressure within the mold, resulting in fiber destruction and mold deformation. Heating the mold and injection resin reduces the viscosity of resin, leading to influence on mold internal pressure. Selection of optimal mold and injection temperature for effective reduction of mold internal pressure has become a source of concern in the polymer industry. This article presents an outlook relationship between mold temperature, injection temperature, and mold internal pressure. It also showcases a temperature selection method angle to addressing this issue. The “FLUENT” software has been secondarily developed that gives an insight in using the three‐dimensional nonisothermal RTM simulation. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136 , 47492.
Transfer molding
Molding (decorative)
Internal pressure
Cite
Citations (9)
Additive manufacturing technology has become a viable solution for making molds for plastic injection molding applications. The molds are usually made of high temperature plastic resins suitable for plastic injection molding. Molding resins have superior mechanical properties necessary to withstand the high temperatures and pressures of the injection molding process. It is known that high temperature mechanical properties of resins influence mold performance but it is not established which properties are most important and to what extent they influence the mold performance. Identifying the most important properties influencing mold performance would help resin manufacturers to develop better mold-making materials. In order to study the performance of mold materials we have built a device for measuring the mechanical properties of 3D printed resins including their strength, surface hardness, and wear resistance at molding temperatures of up to 260 oC. We then quantified the mechanical properties of three high-temperature resins along with ABS at the injection molding temperatures. This paper describes the test device and the results of characterizing the mechanical properties of the selected plastics.
Molding (decorative)
Transfer molding
Compression molding
Cite
Citations (3)
Transfer molding
Molding (decorative)
Cite
Citations (12)