Calculation on the Residual Stresses of Injection-Molded Conductive-Carbon-Fiber-Filled Polymer Composites

2012 ◽  
Vol 629 ◽  
pp. 55-59
Author(s):  
Ai Yun Jiang ◽  
Jing Chao Zou ◽  
Bao Feng Zhang ◽  
Hai Hong Wu
Keyword(s):  
Carbon Fiber ◽  
Residual Stresses ◽  
Polymer Composites ◽  
Injection Molding Process ◽  
Molding Process ◽  
Filled Polymer ◽  
The Core ◽  
Packing Pressure ◽  
Core Areas ◽  
Injection Molded

For conductive-carbon-fiber-filled polymer composites, the residual stresses developed during injection molding process may affect not only the molding’s conductive property, but its dimensional stability as well. In order to improve the conductivity of the molding fabricated with this kind of composites, we investigated, using layer removal method, the distribution of the residual stresses of injection-molded conductive-carbon-fiber-filled polypropylene in this paper. The residual stresses were obtained under the actions of different processing conditions. Our results indicate that processing pressures have more significant effects on the residual stresses at the skin areas than the core areas of the sample because of fiber orientation. The tensile stresses of the molding at the core areas drop under the action of packing pressure, but the compressive stresses at the skin areas increase. The results reveal that the action of packing pressure may decrease the anisotropy of the residual stresses in the molding.

Effect of Injection Molding Process on Electrical Conductivity and Mechanical Property of Nanoparticle Filled Polymer Composites

2012 ◽  
Vol 486 ◽  
pp. 34-38
Author(s):  
Jing Chao Zou ◽  
Ai Yun Jiang ◽  
Bao Feng Zhang ◽  
Hai Hong Wu ◽  
Ya Jun Zhou
Keyword(s):  
Mechanical Properties ◽  
Mechanical Property ◽  
Electrical Conductivity ◽  
Polymer Composites ◽  
Testing Machine ◽  
Injection Pressure ◽  
Processing Parameters ◽  
Injection Molding Process ◽  
Molding Process ◽  
Filled Polymer

Authors investigated the relationship among processing parameters, microstructures, electrical conductivity and mechanical property of injection molded nanoparticle filled polymer composites at present study. Standard tensile specimens were injected under different injecting pressures and packing pressures. The molded specimens were removing five layers from the surface to observe the microstructures at different positions of the moldings. The electrical properties were measured with a two-terminal standard resistor under DC condition at room temperature, and the mechanical properties of the moldings were measured by INSTRON 5580 Universal testing machine. The results showed that filled nanoparticles may form the best conductive path under the higher packing pressure matched with higher injection pressure. The mechanical properties of the molding depend on not only the concentration of the nanofiller, but processing conditions as well.

An effective approach to measuring real-time mold deflection during injection molding

2011 ◽  
Vol 31 (8-9) ◽  
Author(s):  
Chung-Ching Huang ◽  
Thanh-Cong Truong ◽  
Shen-Hong Chen
Keyword(s):  
Injection Molding ◽  
Real Time ◽  
Plate Thickness ◽  
Displacement Sensor ◽  
Injection Molding Process ◽  
Molding Process ◽  
Packing Pressure ◽  
Mold Deformation ◽  
Deflection Analysis ◽  
Injection Molded

Abstract This study develops an effective approach to measure real-time mold plate flexion, namely a displacement of a cavity plate. A mold-filling program was used to simulate the injection molding process. The predicted cavity pressure was then applied as an input for the subsequent mold deflection analysis. In this work, an amorphous polymethyl methacrylate (PMMA) was injection-molded into a 6-inch light guide plate (LGP) cavity, with cavity plate thicknesses of 35 mm, 55 mm, and 100 mm. To validate the predicted mold deflection, an inductive displacement sensor was placed underneath the cavity plate, and experiments were conducted using process variables identical to those of the simulation. Comparison between the simulated results and the experimental data shows that when the cavity plate thickness is reduced, the mold deformation increases significantly, and results in an increase in part thickness. In addition, an increase in packing pressure caused a rise in mold deformation. This study demonstrates that the proposed approach is able to measure the mold deflection.

Development of a Fiber Orientation Measurement Methodology for Injection Molded Thermally-Enhanced Polymers

2012 ◽  
Author(s):  
Timothy Hall ◽  
Arumugham Vaishnavi Subramoniam ◽  
Hugh A. Bruck ◽  
Satyandra K. Gupta
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Polymer Composites ◽  
Fiber Orientation ◽  
Experimental Methodology ◽  
Injection Molding Process ◽  
Molding Process ◽  
Orientation Measurement ◽  
Promising Alternative ◽  
Injection Molded

Thermally-enhanced polymer composites are a promising alternative to exotic metals in seawater heat exchanger applications due to the low cost and corrosion resistance of base polymers and heat transfer rates competitive with corrosion-resistant metals such as titanium or stainless steel. While the properties of thermally-enhanced polymer composites are well-suited for heat exchanger applications, fiber orientation has a strong influence on the structural and thermal performance of the manufactured components. In this study, a method of creating samples, sectioning and polishing them for imaging, microscope sampling for the identification of fibers, image processing to characterize fiber orientation, and finally comparison to predictions from computer-aided engineering (CAE) software is demonstrated for collecting experimental information on fiber orientation of molded parts. Understanding fiber orientation in injection-molded polymer heat exchangers is important for ensuring ideal heat transfer and structural performance and this study presents an experimental methodology for determining the influence of injection molding process parameters on fiber orientation in thermally-enhanced polymer composite geometries.

Comparative Analysis of Different Methods in Residual Stress Measurement for Polymeric Parts

2013 ◽  
Vol 837 ◽  
pp. 175-178
Author(s):  
Alexandra Raicu
Keyword(s):  
Residual Stress ◽  
Residual Stresses ◽  
Stress Measurement ◽  
Polymeric Materials ◽  
Injection Molding Process ◽  
Uniform Temperature ◽  
Molding Process ◽  
Molded Parts ◽  
Injection Molded ◽  
Technological Constraints

This paper presents the measurements of the residual stresses for polymeric parts using different methods. The residual stresses are usually introduced during manufacturing and are caused by processes such as molding. In order to optimize injection molding process with polymeric material, it is important to predict the internal stress development during molding. The residual stresses are caused mainly by non-uniform temperature profile in the cavity during filling, packing and cooling stages. This research offers information and a methodology which may be applied in practical conditions for a large number of parts manufactured from the different polymeric materials and for several technological constraints. The author confirmed that all this methods which measure the residual stresses can be applied to injection molded parts.

scholarly journals Experimental And Numerical Studies of Shrinkage and Sink Marks On Injection Molded Polymer Gears

2021 ◽  
Author(s):  
Bikram Solanki ◽  
Hapreet Singh ◽  
Tanuja Sheorey
Keyword(s):  
Injection Molding ◽  
Injection Molding Process ◽  
Molding Process ◽  
Melt Temperature ◽  
Numerical Studies ◽  
Packing Pressure ◽  
Injection Molded ◽  
Sink Marks ◽  
Plastic Gears ◽  
Packing Time

Abstract Injection molding is an efficient and most economical process employed for the mass production of plastic gears and helps to reduce the processing time and cost required to produce the desired geometry. However, significant process and product qualification of plastic gears face the shrinkage and sink marks issues during cooling and after ejection. In present work, the best gate locations and flow resistance analysis along with a polypropylene (PP) were carried out using Autodesk Moldflow Insight 2019.05. The numerical and experimental study was conducted to evaluate the effect of packing pressure, packing time, and melt temperature on diametric shrinkage, mass, and sink marks of PP gear. The results show that by increasing packing pressure and packing time, the diametric shrinkage decreased but mass increased. However, as the melt temperature increased the diametric shrinkage also increased but the mass decreased. The minimum diametric shrinkage of 0.562% was found in numerical analysis and 1.619% found in an experimental analysis at the same injection molding process parameters. Mostly, the sink marks were observed in the gear surface between hub and dedendum circle.

A Study on the Birefringence Measurement in Injection Molded Parts Using Two Different Laser Sources and R-G-B Separation of White Light

2006 ◽  
Vol 326-328 ◽  
pp. 187-190
Author(s):  
Jong Sun Kim ◽  
Chul Jin Hwang ◽  
Kyung Hwan Yoon
Keyword(s):  
White Light ◽  
Low Cost ◽  
Main Idea ◽  
Injection Molding Process ◽  
Molding Process ◽  
Laser Method ◽  
High Productivity ◽  
Molded Parts ◽  
Injection Molded ◽  
Plastic Parts

Recently, injection molded plastic optical products are widely used in many fields, because injection molding process has advantages of low cost and high productivity. However, there remains residual birefringence and residual stresses originated from flow history and differential cooling. The present study focused on developing a technique to measure the birefringence in transparent injection-molded optical plastic parts using two methods as follows: (i) the two colored laser method, (ii) the R-G-B separation method of white light. The main idea of both methods came from the fact that more information can be obtained from the distribution of retardation caused by different wavelengths. The comparison between two methods is demonstrated for the same sample of which retardation is up to 850 nm.

Effect of gas counter pressure on shrinkage and residual stress for injection molding process

2017 ◽  
Vol 37 (5) ◽  
pp. 505-520 ◽  
Author(s):  
Wen-Ren Jong ◽  
Shyh-Shin Hwang ◽  
Ming-Chieh Tsai ◽  
Chien-Chou Wu ◽  
Chi-Hung Kao ◽  
...  
Keyword(s):  
Residual Stress ◽  
Injection Molding ◽  
Flow Direction ◽  
Injection Molding Process ◽  
Molding Process ◽  
Daily Lives ◽  
Counter Pressure ◽  
Packing Pressure ◽  
Sink Marks ◽  
Feedback Data

Abstract Plastic products are common in contemporary daily lives. In the plastics industry, the injection molding process is advantageous for features such as mass production and stable quality. The problem, however, is that the melt will be affected by the residual stress and shrinkage generated in the process of filling and cooling; hence, defects such as warping, deformation, and sink marks will occur. In order to reduce product deformation and shrinkage during the process of molding, the screw of the injection molding machine will start the packing stage when filling is completed, which continuously pushes the melt into the cavity, thus making up for product shrinkage and improving their appearance, quality, and strength. If the packing pressure is too high, however, the internal residual stress will increase accordingly. This study set out to apply gas counter pressure (GCP) in the injection molding process. By importing gas through the ends of the cavity, the melt was exposed to a melt front pressure, which, together with the packing pressure from the screw, is supposed to reduce product shrinkage. The aim was to investigate the impacts of GCP on the process parameters via the changes in machine feedback data, such as pressure and the remaining injection resin. This study also used a relatively thin plate-shaped product and measurements, such as the photoelastic effect and luminance meter, to probe into the impacts of GCP on product residual stress, while a relatively thick paper-clip-shaped product was used to see the impacts of GCP on shrinkage in thick parts. According to the experimental results, the addition of GCP resulted in increased filling volume, improvement of product weight and stability, and effective reduction of section shrinkage, which was most obvious at the point closest to the gas entrance. The shrinkage of the sections parallel and vertical to the flow direction was proved to be reduced by 32% and 16%, respectively. Moreover, observations made via the polarizing stress viewer and luminance meter showed that the internal residual stress of a product could be effectively reduced by a proper amount of GCP.

A Study on Mechanical Properties of Short Carbon Fiber Reinforced Polycarbonate via an Injection Molding Process

2020 ◽  
Vol 18 (11) ◽  
pp. 801-805
Author(s):  
Kyung-Soo Jeon ◽  
R. Nirmala ◽  
Seong-Hwa Hong ◽  
Yong-II Chung ◽  
R. Navamathavan ◽  
...  
Keyword(s):  
Tensile Strength ◽  
Carbon Fiber ◽  
Carbon Fibers ◽  
Testing Machine ◽  
Fiber Content ◽  
Injection Molding Process ◽  
Mechanical And Thermal Properties ◽  
Molding Process ◽  
Short Carbon Fiber ◽  
Short Carbon

This manuscript is dealt with the synthesis of short carbon fibers reinforced polycarbonate polymer composite by using injection modeling technique. Four different composite materials were obtained by varying the carbon fibers weight percentage of 10, 20, 30 and 40%. The synthesized carbon fibers/polycarbonate composites were characterized for their morphological, mechanical and thermal properties by means of scanning electron microscopy (SEM), universal testing machine (UTM) and IZOD strength test. The resultant carbon fibers/polycarbonate composites exhibited excellent interfacial adhesion between carbon fibers and polycarbonate resin. The tensile properties were observed to be monotonically increases with increasing carbon fiber content in the composite resin. The tensile strength of carbon fiber/polycarbonate composites with the carbon fiber content 40% were increased about 8 times than that of the pristine polycarbonate matrix. The carbon fibers/polycarbonate composites with 40 wt.% of short carbon fibers exhibited a high tensile strength and thermal conductivity. The incorporation of carbon fiber in to polycarbonate resin resulted in a significant enhancement in the mechanical and the thermal behavior. These studies suggested that the short carbon fiber incorporated polycarbonate composite matrix is a good candidate material for many technological applications.

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