Papers by Keyword: Injection Molding

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Authors: He Sheng Liu, Ai Hua Xiong, Xing Yuan Huang, Jia Mei Lai
Abstract: Based on generalized non-Newtonian fluid with seven parameters Cross-WLF viscosity model and modified 2-domain Tait model, the injection process of short glass fiber-reinforced polypropylene is simulated with a true 3D model. The effects of gate location on clamp force, fiber orientation and parts deformation are investigated. The results show that: (1) Clamp force of the 3rd scheme that gate location is set on the center of long-side is the largest and that of the 1st scheme that gate location is set on the center of top is the smallest. (2)Because of shear stress, in the direction of thickness, the distributions of fiber orientation are layered orderly, namely, the degree of fiber orientation in core layer is the lowest, but that in subsurface layer is the highest. While perpendicular to the shear flow, the layering distribution isn’t obvious. (3) Compared the three schemes in respect of clamp force and parts deflection, the 3rd scheme is the poorest, which should not be adopted as can as possible, while the 1st scheme and 2nd scheme are reasonable.
Authors: G. Darshan, S.K. Vijayasimha, Ramasami Sivakumar
Abstract: This study is an attempt to close the loop between simulation and reality. Many industries are of the opinion that a simulation does not really predict the actual process and is only a colorful plot for presentation. An accurate simulation can save cost by a multitude of ways like material savings, process optimization, cycle time reduction, improved quality of parts and so on. A validation of the simulation in a real time scenario will instil necessary confidence in the accuracy of the simulation study thereby closing the loop between simulation and reality In the present study, the mold flow analysis is conducted for the back plate of LED emergency light with the help of Autodesk moldflow simulation software to generate the gate location, feed system building, cooling channel wizard, fill time and to check warpage and then the result is verified by superimposing the scan data of the physical part which is scanned in Steinbichler Blue Light 3D Scanner and CAD model in Geomagic verify.
Authors: Wei Fang, Xin Bo He, Rui Jie Zhang, Xuan Hui Qu
Abstract: Attempts have been made to develop a gray value-matching detection method for quantitative evaluation of defects and density of green parts in metal injection moulding, based on the analysis of X-ray digital radiography images. The results show that the range of gray values should be in about 1.4% when the dimensional accuracy is required within 0.3%, and voids are present where fluctuation of the gray value is larger than 10%. The quantitative evaluation of voids, powder content and density distribution through the gray value-matching can respectively predict severity of voids, shrinkage, and deformation in the sintering stage. Furthermore, the ability to detect defects and particle density distribution of this method allows for the development of an inference system to predict the optimal parameters.
Authors: Wan Nur Azrina Wan Muhammad, Mohd Hilmi Othman, Sulaiman Hasan, Muhammad Faiz Ruslee
Abstract: Injection moulding is one of the most efficient processes in mass production that can easily attain up to complex geometry product within a very short cycle time. To choose a suitable setting of parameter was very crucial, in controlling the quality of product with regard to their function. The main propose of this research is to optimize the injection moulding parameter for controlling the shrinkage and warpage of thermoplastics sample through practical injection moulding. The additional study for this project is to investigate the effect of nanoclay contents towards the parameter setting. In this experiment, the selected parameters were packing pressure; melt temperature, screw speed and filling time. The material that was selected for this project was a mixture of polypropylene and nanoclay with the addition of polypropylene-grafted-maleic anhydride as the compatibilizer. Three formulations were chosen, which was 0 wt%, 3 wt% and 5 wt% of Nanoclay. Each formulation was added with 15 wt% of compatibilizer. The experiment design for this project shall adopt the L943 Orthogonal Array of Taguchi Method. By using the Signal to Noise Ratio responses, the optimum parameter for each formulation has been obtained. The findings of this experiment shall be useful for future manufacturing process in order to control shrinkage and warpage specifically for products made from polypropylene-nanoclay.
Authors: Jae Young Choi, Ho Youn Kim, Jae Hong Park, Hae Do Jeong, Heonduc Seo
Authors: N. Duangphattra, C. Aramphongphun
Abstract: This research work studies the effects of processing conditions on mechanical properties of polymer nanocomposites. Polypropylene (PP) nanocomposites reinforced with 0.5 and 2.5 %wt multiwall carbon nanotubes (MWCNTs) were prepared via melt compounding and formed by injection molding. 2k Full Factorial design was used to plan the experiments and determine the influences of the processing conditions on mechanical properties and carbon nanotube dispersion in the nanocomposites. These conditions consist of five factors: (a) %wt content of MWCNTs (0.5 and 2.5 %wt), (b) barrel temperature (190 and 220°C), (c) injection velocity (25 and 45 mm/sec), (d) screw rotational speed (75 and 227 rpm) and (e) holding pressure (45 and 65 bar) while injection pressure and cooling time were set at 75 bar and 50 sec, respectively, for all conditions. The samples were examined by Young’s modulus and tensile strength using a Universal Testing Machine (UTM). In addition, Scanning Electron Microscopy (SEM) was applied to study the dispersion of carbon nanotubes in the nanocomposites. The results showed that PP/MWCNT nanocomposites had Young’s modulus of 1,740 MPa and tensile strength of 34.5 MPa while original PP had 1,450 MPa and 28 MPa, respectively. Therefore, the mechanical properties were improved significantly with the content of MWCNTs. Full Factorial experiments investigate that significant factors are %wt, barrel temperature, injection velocity, and screw rotational speed. Moreover, SEM showed that a high content of MWCNTs led to a highly oriented skin layer with well-dispersed MWCNTs.
Authors: Chao Chang Arthur Chen, Shi Chi Kao
Abstract: This research aimed to develop a novel two-stage micro injection compression molding (μ-ICM) process for fabrication of plastic diffractive optic elements (DOE). The DOE was designed with the spherical coefficients and the Fresnel lens. A piezo actuator was installed inside the mold plate for activating the mold insert for the second compression motion for micro ICM of the DOE lens. The first experiment proceeded to find the operation window of Fresnel lens and then compare the product weight of flat spherical lens by injection molding (IM), injection compression molding (ICM) and μ-ICM. The second experiment was to investigate the effectiveness of micro compression activated by the piezo actuator by the transfer ratio of grooves (TRG) of the DOE lens with spherical lens and Fresnel lens. Results showed that the μ-ICM of the DOE can obtain the highest TRG than that of IM and conventional ICM processes. Therefore, results of this research can be explored to related aspheric optical elements with micro features, such as fine lens used in the zoom lens of camera.
Authors: W. Li, Yang Fu Jin, Xun Lv, C.H. Kua
Abstract: In this paper, some molding process parameters such as injection time, packing time, packing pressure and process temperature etc. were optimized by the Computer Aided Engineering (CAE) simulation (Moldex 3D) for injection molding of a plastic lens. Some experimental trials were carried out for verifying of the CAE simulation results with checking of the lens shrinkage and birefringence etc. as well. The results showed that, the recommended molding process parameters from CAE simulation and the actual experiments were almost the same, hence the CAE is a established tool based on the scientific approach to reduce experimental works, to identify critical parameters and to save substantial costs. Lately, a perfect plastic lens was gained by the Injection–Compression Molding process with the optimized process parameters by a CAE simulation.
Authors: Jing Bo Chen, Chang Yu Shen, Hidetoshi Yokoi
Abstract: Filling imbalance for PP, long GF-PP, elastomer PC and GF-PC in a multi-cavity mold with a geometrically balanced runner is investigated by using the visualization glass-inserted injection mold and infrared thermometers, through visualizing the flow behavior of the melt in the runner and cavity and measuring the melt temperature near the cavity entrance simultaneously. In addition, velocity distribution in the secondary runner for PP and elastomer is also determined by use of marker tracers in order to further investigate the mechanism of filling balance. The results show that the degree of filling imbalance depends on the velocity difference of the upper and lower melt and its development in the secondary runner during the filling process. The melt viscosity difference in the primary runner dominate the melt velocity difference in the secondary runner., and the viscosity difference depends on the temperature difference and viscosity sensitivity to temperature and shear rate. The development of the velocity difference of the upper and lower melt in the secondary runner depends on the melt viscoelastic property and the runner wall condition.
Authors: Chul Woo Park, Seong Ho Seo
Abstract: Injection molding process one of the most important methods to produce plastic parts with high efficiency and low cost. Today, Injection molded parts have been increased dramatically the demand for high strength and quality applications. In this study, truck brake pedal is made of Cast iron and plastic materials to replace the frame for the optimization process that minimizes the runner and the gate dimension will determine the size and shape. Runner and gate dimensions of change based on availability of the product. I will discuss the injection molding. This report investigates that the optimum injection molding condition for minimum of runner and gate position. The FEM Simulation CAE tool, MOLDFLOW, is used for the analysis of injection molding process.
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