Experimental study of penetration interfaces in the overflow fluid-assisted co-injection molding process

2016 ◽  
Vol 36 (2) ◽  
pp. 139-148 ◽  
Author(s):  
Tangqing Kuang ◽  
Chuncong Yu ◽  
Baiping Xu ◽  
Lih-Sheng Turng
Keyword(s):  
Experimental Study ◽  
Injection Molding ◽  
Cross Section ◽  
High Density Polyethylene ◽  
Flow Direction ◽  
Injection Molding Process ◽  
Molding Process ◽  
The Difference ◽  
The Stability ◽  
Plastic Products

Abstract The fluid-assisted co-injection molding (FACIM) process can be used to produce hollow plastic products with outer and inner layers. It can be divided into two categories: water-assisted co-injection molding (WACIM) and gas-assisted co-injection molding (GACIM). An experimental study of penetration interfaces in overflow FACIM was carried out based on a lab-developed FACIM system. High-density polyethylene and polypropylene were used as the outer layer and inner layer plastics, respectively, in the experiments and the injection sequence was reversible. Six cross-section cavities were investigated in the experiments. The penetration behaviors of water and gas in different sequences and cavities were compared and analyzed. The penetration interfaces were characterized by the residual wall thickness (RWT). The experimental results showed that the RWT of the inner layer in WACIM fluctuated along the flow direction, while that in GACIM was more even. The difference of viscosity between the outer and inner layer melts affected the stability of the interface between them. The penetration sections of the inner layer and the gas were closer to the cavity sections in GACIM, while the penetration sections of the inner layer and the water were closer to the circular forms in WACIM.

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.

Estimation of Maximum Flow Length for CF-PEEK Overmolded Grid Structures Using the Finite Element Method

2021 ◽  
Author(s):  
Carlos Rodríguez-Mondéjar ◽  
Álvaro Rodríguez-Prieto ◽  
Ana María Camacho
Keyword(s):  
Aspect Ratio ◽  
Injection Molding ◽  
Cross Section ◽  
Maximum Flow ◽  
Thermoplastic Composites ◽  
Injection Molding Process ◽  
Geometrical Parameters ◽  
Molding Process ◽  
Support Tool ◽  
Flow Length

Abstract Injection overmolding process is a high versatile process that permits, when used in combination with fiber reinforced thermoplastic composites, the obtaining of high mechanical properties structures with complex geometries in short time cycles. The maximum flow length is a parameter that reflects the success of filling in a polymer injection molding process. Geometry of the part, rheological properties of the polymer and process parameters, such as injection pressure and temperature, are involved on the value of this parameter and therefore on the viability of a certain configuration. For injection molding manufacturing, the understanding of the relation between maximum flow length and main geometrical parameters of the molded part is fundamental to approach the product design, which is conditioned severely by processing capabilities. In this work, the maximum flow length is obtained for different geometries of an overmolded rectangular stiffener grid of carbon fiber filled polyether eter ketone (CF-PEEK) using the software Moldflow© Adviser© for calculations. Value of maximum flow length is provided as a function of cross section aspect ratio for gate diameters between 0.8 mm and 1.4 mm and cross section areas from 10 to 50 mm2. An exponential decrement of maximum flow length has been observed with the increment of aspect ratio of the cross section as well as a linear increment with the increment of cross section area. Gate diameter variation is slightly related with maximum flow length for the simulated values. These results provide a support tool for geometry sizing in overmolded rectangular grid parts at preliminary design stages.

An Experimental Evaluation of Vibration-Assisted Injection Molding During Manufacturing

1999 ◽  
Author(s):  
Alan M. Tom ◽  
Akihisa Kikuchi ◽  
John P. Coulter
Keyword(s):  
Experimental Study ◽  
Injection Molding ◽  
Scientific Explanation ◽  
Molecular Level ◽  
Injection Molding Process ◽  
Processing Conditions ◽  
Vibrational Motion ◽  
Current Investigation ◽  
Molding Process ◽  
Polymer Properties

Abstract The current investigation focused on contributing to the development of a novel injection molding process by attempting to understand the scientific relationship that exist between the applied vibrational parameters involved in this process and the effect it has on final product polymeric characterization. Although previous and current attempts at understanding the connection between applied oscillatory or vibrational motion to an injection molding process has shown positive quantitative advantages to final product properties, there still exists a void in the scientific explanation on a molecular level linking these effects. This experimental study, in particular, involved an evaluation on a range of processing conditions applied to Polystyrene and the effects it produced on resultant product quality and polymer properties. Optimal control and mechanical vibrational molding conditions were obtained for Polystyrene. As a result of this, optimal opportunities for initial commercial utilization of the technology can be proposed.

Skin-Core Micro-Structure and Surface Orientation of Carbon Nanotube Composites by Injection Molding Process

2008 ◽  
Vol 136 ◽  
pp. 51-56 ◽  
Author(s):  
Zhi Fei Li ◽  
Guo Hua Luo ◽  
Wei Ping Zhou ◽  
Fei Wei
Keyword(s):  
Carbon Nanotube ◽  
Injection Molding ◽  
The Body ◽  
Injection Molding Process ◽  
Molding Process ◽  
Nanotube Composites ◽  
Degree Of Orientation ◽  
The Difference ◽  
Conductive Property ◽  
Poly Ethylene

Multi-walled carbon nanotube (MWNT) was filled into poly (ethylene terephthalate) (PET) matrix and MWNT/PET composite was prepared by injection molding process. The microstructure and electrical conductive property were investigated carefully. After injection molding, the electrical conductivity of injected sample decreased sharply because of the orientation of CNT due to strong shearing force. The electrical conductive network of CNT had been destroyed after orientation of CNT. Because of the difference of shearing rate between the surface and the body center during the injection molding process, a skin-core structure emerged. Near the surface, the injected sample has higher degree of orientation of CNT and higher electrical resistance.

MPI-Based Injection Molding Process Optimization Analysis of the Control Plastic Cover

2011 ◽  
Vol 271-273 ◽  
pp. 1224-1227
Author(s):  
Fang Qi Cheng
Keyword(s):  
Injection Molding ◽  
Process Simulation ◽  
Filling Pressure ◽  
Injection Molding Process ◽  
Cooling Process ◽  
Forming Process ◽  
Molding Process ◽  
Optimization Analysis ◽  
Mould Design ◽  
Plastic Products

To avoid the defects of plastic products and improve product quality have been an important problem for mold designers. In this paper, Autodesk Moldflow software are applied to a plastic control cover injection molding process simulation and find out the actual molding process and true conditions of the dynamic filling, pressure and cooling process in the process of forming. The forming process of parameters such as pressure, temperature and speed are given in order to improve the accuracy of the mould design and product precision.

The Visualization Research on Cavitation Flaw of the Jubilance Toy's Part with Different Wall Thickness

2012 ◽  
Vol 479-481 ◽  
pp. 45-49
Author(s):  
Yong Li ◽  
Yu Xin Zhang ◽  
Zhi Qiang Sun ◽  
Rui Zhu Zhang
Keyword(s):  
Experimental Study ◽  
Injection Molding ◽  
Wall Thickness ◽  
Technological Parameter ◽  
Injection Molding Process ◽  
Kinetic Simulation ◽  
Molding Process

The injection molding process with different wall thickness may create the obvious cavitation flaw. So carried on the kinetic simulation of filling injection using plastic advisor with Pro/E software, and discussed the melt flows in the mould. Research the cavitation defect of the jubilance toy's part with different wall thickness, and forecast reasonably position and quantity of the cavitation, and through the change of formation technological parameter, obtained the relatively good formation technological combination, achieved the reduced flaw quantity. Which provided the theory basis to study and removes the product flaw, provided reference for the discussion injection CAE, indicated it had great singlenificance for the visualization experimental study.

Rice Husk/High Density Polyethylene Bio-Composite: Effect of Rice Husk Filler Size and Composition on Injection Molding Processability with Respect to Impact Property

2009 ◽  
Vol 83-86 ◽  
pp. 367-374 ◽  
Author(s):  
Wan Aizan Wan Abd. Rahman ◽  
N.M. Isa ◽  
A.R. Rahmat ◽  
N. Adenan ◽  
R.R. Ali
Keyword(s):  
Impact Strength ◽  
Injection Molding ◽  
Rice Husk ◽  
High Density Polyethylene ◽  
Injection Molding Process ◽  
Melt Flow ◽  
Molding Process ◽  
Melt Flow Rate ◽  
Filler Size ◽  
The Impact

The compounding of rice husk and high density polyethylene (HDPE) was undertaken on a Sino PSM 30 co-rotating twin screw extruder. Four sizes of rice husk were studied at various compositions. The size ranged from 500 μm and below (coded A, B, C and D) while the content of rice husk in the composite varies from 30, 40 and 50 percent of weight. A fixed amount of Ultra-Plast TP10 as a compatibilizer and Ultra-Plast TP 01 as lubricant, were added into the bio-composite compound. The injection molding process ability of the bio-composite was studied through flow behavior on melt flow indexer and analyzed on JSW N100 B11 Injection Molding. Size A which has the largest particle is the most appropriate size as the bio-composite filler based on thermal stability test. The melt flow rate of rice husk/HDPE (RHPE) decreases with the increased in rice husk compositions and apparent viscosity also increases with composition for all filler size. Melt flow rate above 4g/10 min was found to be the lower limit for injection molding process. The smaller the filler size, the lower is the impact strength and the increased in the filler composition lowers the impact strength. A bio-composite at 30 weight percent rice husk size A (RH30PEA) was found to have optimum rheological properties with respect to impact strength.

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