The Experts below are selected from a list of 106191 Experts worldwide ranked by ideXlab platform
Guilong Wang - One of the best experts on this subject based on the ideXlab platform.
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Heating cooling channels design for an automotive interior part and its evaluation in rapid Heat Cycle molding
Materials & Design, 2014Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed innovative injection molding technology. Rapid Heating and cooling of the injection mold is the most crucial technique in RHCM because it not only has a significant effect on part quality but also has direct influence on productivity and cost-efficiency. Accordingly, Heating and cooling system design plays a very important role in RHCM mold design. This study focuses on the Heating/cooling system design for a three-dimensional complex-shaped automotive interior part. Heat transfer simulation based on finite element analysis (FEA) was conducted to evaluate the thermal response of the injection mold and thereby improve Heating/cooling channels design. Baffles were introduced for Heating/cooling channels to improve Heating/cooling efficiency and uniformity of the mold. A series of thermal response experiments based on full factorial experimental design were conducted to verify the effectiveness of the improved Heating/cooling channels design with baffles. A mathematical model was developed by regression analysis to predict the thermal response of the injection mold. The effects of the cavity surface temperature on weld mark and surface gloss of the part were investigated by experiments. The results show that the developed baffle-based Heating/cooling channels can greatly improve thermal response efficiency and uniformity of the mold. The developed mathematical model supplies an efficient approach for precise predication of mold thermal response. As the cavity surface temperature raises to a high enough level, automotive interior parts with high gloss and non-weld mark surface can be obtained.
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research on the reduction of sink mark and warpage of the molded part in rapid Heat Cycle molding process
Materials & Design, 2013Co-Authors: Xiaoxin Wang, Guoqun Zhao, Guilong WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed innovative injection molding technology to enhance the surface quality of the plastic parts without extending the molding Cycle. Most of the common defects that occur in the plastic parts produced by conventional injection molding (CIM), such as flow mark, silver mark, jetting mark, weld mark, exposed fibers, short shot, etc., can be well solved by RHCM. However, RHCM is not a nostrum for all the defects in injection molding. Sink mark and warpage are two major defects occurring in RHCM. The purpose of this study is to investigate and further solve the sink mark and warpage of the molded parts in RHCM. To solve the problem of sink mark, a new “bench form” structure for the screw stud on the product coupling with a lifter structure for the injection mold was proposed. The external gas assisted packing was also proposed to reduce the sink mark in RHCM. To solve the problem of warpage, design of experiments via Taguchi methods were performed to systematically investigate the effect of processing parameters including melt temperature, injection time, packing pressure, packing time and also cooling time on the warpage. Injection molding simulations based on Moldflow were conducted to acquire the warpages of the plastic parts produced under different processing conditions. A signal to noise analysis was conducted to analyze the effect of the factors, and the optimal processing parameters were also found out. ANOVA was also conducted to quantitatively analyze the percentage contributions of the processing parameters on the warpage. The verification results show that part warpage can be reduced effectively based on the optimal design results.
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effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid Heat Cycle molding
Materials & Design, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed injection molding technology to enhance surface esthetic of the parts. By rapid Heating and cooling of mold cavity surfaces in molding process, it can greatly alleviate or even eliminate the surface defects such as flow mark, weld line, glass fiber rich surface, silver mark, jetting mark, and swirl mark, and also improve gloss finish and dimensional accuracy without prolonging the molding Cycle. Besides surface esthetic, mechanical property is also a very import issue for the molded plastic part. The aim of this study is focusing on the effects of the cavity surface temperature just before filling, T cs , in RHCM on the mechanical strength of the specimen with and without weld line. Six kinds of typical plastics including polystyrene (PS), polypropylene (PP), acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene/polymethylmethacrylate (ABS/PMMA), ABS/PMMA/nano-C a CO 3 and glass fiber reinforced polypropylene (FRPP) are used in experiments. The specimens with and without a weld line are produced with the different T cs on the developed electric-Heating RHCM system. Tensile tests and notched Izod impact tests are conducted to characterize the mechanical strength of the specimens molded with different cavity surface temperatures. Simulations, differential scanning calorimetry (DSC), scanning electron microscope (SEM) and optical microscope are implemented to explain the impact mechanism of T cs on mechanical properties.
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experimental research on the effects of cavity surface temperature on surface appearance properties of the moulded part in rapid Heat Cycle moulding process
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:The influences of the cavity surface temperature just before filling on part surface appearance and texture in rapid Heat Cycle moulding are investigated. It is observed that the cavity surface temperature just before filling has a very significant influence on part surface appearance. As the cavity surface temperature increases, aesthetic quality of the moulded part can be greatly improved by reducing surface roughness, increasing surface gloss and reducing weld mark. There is a critical cavity surface temperature just before filling for each plastic material. As the cavity surface temperature reaches the critical value, the part surface appearance will reach the optimal level with lowest roughness, highest gloss and without any weld mark. The critical cavity surface temperature on surface gloss and roughness is close to the Vicat softening point of the plastic material. The critical cavity surface temperature on weld mark is 10–20 °C higher than that on surface roughness and gloss. The mechanisms for generating the rough surface of the part moulded with a low cavity surface temperature and improving part surface appearance by increasing cavity surface temperature are disclosed.
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Effects of cavity surface temperature on reinforced plastic part surface appearance in rapid Heat Cycle moulding
Materials & Design, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract The influences of the cavity surface temperature just before filling on surface appearance and texture of the moulded reinforced plastic parts in rapid Heat Cycle moulding (RHCM) are investigated. Two typical reinforced plastics including ABS/PMMA/nano-C a CO 3 and 20% fibre reinforced polypropylene (FRPP) are tested in experiments. The roughness, gloss and morphology of the part surface are characterized with white light interferometer, gloss meter, and optical microscope, respectively. It is observed that the cavity surface temperature just before filling has a significant influence on part surface appearance. With the increase of the cavity surface temperature just before filling, aesthetic quality of the moulded part can be greatly improved. There is a critical value of the cavity surface temperature just before filling for each plastic. As the cavity surface temperature reaches the critical value, part surface appearance will reach the optimal level with low roughness and high gloss. The weld mark for ABS/PMMA/nano-C a CO 3 has a V-shaped structure while that for FRPP has a hump-shaped structure. With the increase of the cavity surface temperature just before filling, the width of the V-shaped weld mark reduces gradually until it disappears completely while the height of the hump-shaped weld mark decreases firstly and then increases. The mechanisms for the improvement of surface appearance by increasing cavity surface temperature just before filling and the generation of the V-shaped and hump-shaped weld mark are disclosed.
Guoqun Zhao - One of the best experts on this subject based on the ideXlab platform.
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effects of mold cavity temperature on surface quality and mechanical properties of nanoparticle filled polymer in rapid Heat Cycle molding
Journal of Applied Polymer Science, 2015Co-Authors: Aimin Zhang, Guoqun Zhao, Yanjin GuanAbstract:Acrylonitrile-butadiene-styrene (ABS)/poly methyl methacrylate (PMMA) and ABS/PMMA/nano-CaCO3 composites were prepared in a corotating twin screw extruder. Single-gate and double-gate samples were molded based on a rapid Heat Cycle molding (RHCM) system. Effects of mold cavity temperature on surface quality and mechanical properties of single-gate and double-gate samples in RHCM process were conducted. The results showed that surface quality of plastic parts can be improved significantly by increasing mold cavity temperature. Nano-CaCO3 particles on the surface of plastic parts can be eliminated by using high mold cavity temperature. The roughness and gloss of two kinds of plastic parts (ABS/PMMA and ABS/PMMA/nano-CaCO3) stabilized at the same level when the mold cavity temperature is above glass transition temperature of resin material. Weld line can be eliminated in RHCM process during high mold cavity temperature. The tensile strength of both ABS/PMMA and ABS/PMMA/nano-CaCO3 exhibited decreasing trend with the increase of mold cavity temperature. Reduction of internal stress gave rise to the increase of Izod impact strength of ABS/PMMA for both sing-gate and double-gate samples. However, influence regularity of mold cavity temperature on Izod impact strength of ABS/PMMA/nano-CaCO3 is depended on the number of gates. For all the samples in this study, too high of mold cavity temperature (higher than 125°C) deprave Izod impact strength of plastic parts. Both ABS/PMMA and ABS/PMMA/nano-CaCO3 are not susceptible to weld line. When the mold surface temperature is approximately equal to glass transition temperature of resin material, all the samples are found to give the best combination of properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41420.
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Heating cooling channels design for an automotive interior part and its evaluation in rapid Heat Cycle molding
Materials & Design, 2014Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed innovative injection molding technology. Rapid Heating and cooling of the injection mold is the most crucial technique in RHCM because it not only has a significant effect on part quality but also has direct influence on productivity and cost-efficiency. Accordingly, Heating and cooling system design plays a very important role in RHCM mold design. This study focuses on the Heating/cooling system design for a three-dimensional complex-shaped automotive interior part. Heat transfer simulation based on finite element analysis (FEA) was conducted to evaluate the thermal response of the injection mold and thereby improve Heating/cooling channels design. Baffles were introduced for Heating/cooling channels to improve Heating/cooling efficiency and uniformity of the mold. A series of thermal response experiments based on full factorial experimental design were conducted to verify the effectiveness of the improved Heating/cooling channels design with baffles. A mathematical model was developed by regression analysis to predict the thermal response of the injection mold. The effects of the cavity surface temperature on weld mark and surface gloss of the part were investigated by experiments. The results show that the developed baffle-based Heating/cooling channels can greatly improve thermal response efficiency and uniformity of the mold. The developed mathematical model supplies an efficient approach for precise predication of mold thermal response. As the cavity surface temperature raises to a high enough level, automotive interior parts with high gloss and non-weld mark surface can be obtained.
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research on the reduction of sink mark and warpage of the molded part in rapid Heat Cycle molding process
Materials & Design, 2013Co-Authors: Xiaoxin Wang, Guoqun Zhao, Guilong WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed innovative injection molding technology to enhance the surface quality of the plastic parts without extending the molding Cycle. Most of the common defects that occur in the plastic parts produced by conventional injection molding (CIM), such as flow mark, silver mark, jetting mark, weld mark, exposed fibers, short shot, etc., can be well solved by RHCM. However, RHCM is not a nostrum for all the defects in injection molding. Sink mark and warpage are two major defects occurring in RHCM. The purpose of this study is to investigate and further solve the sink mark and warpage of the molded parts in RHCM. To solve the problem of sink mark, a new “bench form” structure for the screw stud on the product coupling with a lifter structure for the injection mold was proposed. The external gas assisted packing was also proposed to reduce the sink mark in RHCM. To solve the problem of warpage, design of experiments via Taguchi methods were performed to systematically investigate the effect of processing parameters including melt temperature, injection time, packing pressure, packing time and also cooling time on the warpage. Injection molding simulations based on Moldflow were conducted to acquire the warpages of the plastic parts produced under different processing conditions. A signal to noise analysis was conducted to analyze the effect of the factors, and the optimal processing parameters were also found out. ANOVA was also conducted to quantitatively analyze the percentage contributions of the processing parameters on the warpage. The verification results show that part warpage can be reduced effectively based on the optimal design results.
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effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid Heat Cycle molding
Materials & Design, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed injection molding technology to enhance surface esthetic of the parts. By rapid Heating and cooling of mold cavity surfaces in molding process, it can greatly alleviate or even eliminate the surface defects such as flow mark, weld line, glass fiber rich surface, silver mark, jetting mark, and swirl mark, and also improve gloss finish and dimensional accuracy without prolonging the molding Cycle. Besides surface esthetic, mechanical property is also a very import issue for the molded plastic part. The aim of this study is focusing on the effects of the cavity surface temperature just before filling, T cs , in RHCM on the mechanical strength of the specimen with and without weld line. Six kinds of typical plastics including polystyrene (PS), polypropylene (PP), acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene/polymethylmethacrylate (ABS/PMMA), ABS/PMMA/nano-C a CO 3 and glass fiber reinforced polypropylene (FRPP) are used in experiments. The specimens with and without a weld line are produced with the different T cs on the developed electric-Heating RHCM system. Tensile tests and notched Izod impact tests are conducted to characterize the mechanical strength of the specimens molded with different cavity surface temperatures. Simulations, differential scanning calorimetry (DSC), scanning electron microscope (SEM) and optical microscope are implemented to explain the impact mechanism of T cs on mechanical properties.
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experimental research on the effects of cavity surface temperature on surface appearance properties of the moulded part in rapid Heat Cycle moulding process
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:The influences of the cavity surface temperature just before filling on part surface appearance and texture in rapid Heat Cycle moulding are investigated. It is observed that the cavity surface temperature just before filling has a very significant influence on part surface appearance. As the cavity surface temperature increases, aesthetic quality of the moulded part can be greatly improved by reducing surface roughness, increasing surface gloss and reducing weld mark. There is a critical cavity surface temperature just before filling for each plastic material. As the cavity surface temperature reaches the critical value, the part surface appearance will reach the optimal level with lowest roughness, highest gloss and without any weld mark. The critical cavity surface temperature on surface gloss and roughness is close to the Vicat softening point of the plastic material. The critical cavity surface temperature on weld mark is 10–20 °C higher than that on surface roughness and gloss. The mechanisms for generating the rough surface of the part moulded with a low cavity surface temperature and improving part surface appearance by increasing cavity surface temperature are disclosed.
Yanjin Guan - One of the best experts on this subject based on the ideXlab platform.
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effects of mold cavity temperature on surface quality and mechanical properties of nanoparticle filled polymer in rapid Heat Cycle molding
Journal of Applied Polymer Science, 2015Co-Authors: Aimin Zhang, Guoqun Zhao, Yanjin GuanAbstract:Acrylonitrile-butadiene-styrene (ABS)/poly methyl methacrylate (PMMA) and ABS/PMMA/nano-CaCO3 composites were prepared in a corotating twin screw extruder. Single-gate and double-gate samples were molded based on a rapid Heat Cycle molding (RHCM) system. Effects of mold cavity temperature on surface quality and mechanical properties of single-gate and double-gate samples in RHCM process were conducted. The results showed that surface quality of plastic parts can be improved significantly by increasing mold cavity temperature. Nano-CaCO3 particles on the surface of plastic parts can be eliminated by using high mold cavity temperature. The roughness and gloss of two kinds of plastic parts (ABS/PMMA and ABS/PMMA/nano-CaCO3) stabilized at the same level when the mold cavity temperature is above glass transition temperature of resin material. Weld line can be eliminated in RHCM process during high mold cavity temperature. The tensile strength of both ABS/PMMA and ABS/PMMA/nano-CaCO3 exhibited decreasing trend with the increase of mold cavity temperature. Reduction of internal stress gave rise to the increase of Izod impact strength of ABS/PMMA for both sing-gate and double-gate samples. However, influence regularity of mold cavity temperature on Izod impact strength of ABS/PMMA/nano-CaCO3 is depended on the number of gates. For all the samples in this study, too high of mold cavity temperature (higher than 125°C) deprave Izod impact strength of plastic parts. Both ABS/PMMA and ABS/PMMA/nano-CaCO3 are not susceptible to weld line. When the mold surface temperature is approximately equal to glass transition temperature of resin material, all the samples are found to give the best combination of properties. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41420.
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thermal response of an electric Heating rapid Heat Cycle molding mold and its effect on surface appearance and tensile strength of the molded part
Journal of Applied Polymer Science, 2012Co-Authors: Guilong Wang, Guoqun Zhao, Yanjin GuanAbstract:Rapid Heat Cycle molding (RHCM) is a newly developed injection molding technology in recent years. In this article, a new electric Heating RHCM mold is developed for rapid Heating and cooling of the cavity surface. A data acquisition system is constructed to evaluate thermal response of the cavity surfaces of the electric Heating RHCM mold. Thermal cycling experiments are implemented to investigate cavity surface temperature responses with different Heating time and cooling time. According to the experimental results, a mathematical model is developed by regression analysis to predict the highest temperature and the lowest temperature of the cavity surface during thermal cycling of the electric Heating RHCM mold. The verification experiments show that the proposed model is very effective for accurate control of the cavity surface temperature. For a more comprehensive analysis of the thermal response and temperature distribution of the cavity surfaces, the numerical-method-based finite element analysis (FEA) is used to simulate thermal response of the electric Heating RHCM mold during thermal cycling process. The simulated cavity surface temperature response shows a good agreement with the experimental results. Based on simulations, the influence of the power density of the cartridge Heaters and the temperature of the cooling water on thermal response of the cavity surface is obtained. Finally, the effect of RHCM process on surface appearance and tensile strength of the part is studied. The results show that the high-cavity surface temperature during filling stage in RHCM can significantly improve the surface appearance by greatly improving the surface gloss and completely eliminating the weld line and jetting mark. RHCM process can also eliminate the exposing fibers on the part surface for the fiber-reinforced plastics. For the high-gloss acrylonitrile butadiene styrene/polymethyl methacrylate (ABS/PMMA) alloy, RHCM process reduces the tensile strength of the part either with or without weld mark. For the fiber-reinforced plastics of polypropylene (PP) + 20% glass fiber, RHCM process reduces the tensile strength of the part without weld mark but slightly increases the tensile strength of the part with weld mark. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
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research on optimization design of the Heating cooling channels for rapid Heat Cycle molding based on response surface methodology and constrained particle swarm optimization
Expert Systems With Applications, 2011Co-Authors: Guilong Wang, Huiping Li, Guoqun Zhao, Yanjin GuanAbstract:Research highlights? We develop a method for optimum Heating/cooling channels design of RHCM mold. ? A multi-objective optimization method is developed based on RSM and PSO. ? Energy equations in the Heating and cooling processes of RHCM are deduced. ? Some guidelines to improve thermal response efficiency of RHCM mold are presented. The aim of this work is to optimize the layout of the Heating/cooling channels for rapid Heat Cycle molding with hot medium Heating and coolant cooling by using response surface methodology and optimization technique. By means of a Box-Behnken experiment design technique, an experiment matrix with three factors and three levels was designed. The design variables including the diameter of the Heating/cooling channels, distances from the wall of Heating/cooling channel to the cavity surface and between the adjacent Heating/cooling channels were used to describe the layout and shape of the Heating/cooling channels. The Heating efficiency, standard deviation of the cavity surface temperature and the maximum von-mises stress were considered as the model variables. Thermal response and structural strength analyses of the mold based on FEM were conducted to acquire the objective variables for combination of process parameters. Some mathematical models of response surface were created by the mixed regression model and response surface method. The analysis of variance (ANOVA) method was used to check the accuracy of the developed mathematical models. With these mathematical models, the layout of the Heating/cooling channels was then optimized to minimize the required Heating time within reasonable temperature distribution and structural strength of the cavity by coupling the developed response surface (RS) models with the particle swarm optimization (PSO) method.
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research and application of a new rapid Heat Cycle molding with electric Heating and coolant cooling to improve the surface quality of large lcd tv panels
Polymers for Advanced Technologies, 2011Co-Authors: Guoqun Zhao, Guilong Wang, Yanjin Guan, Huiping LiAbstract:The usage of rapid Heat Cycle molding (RHCM) has gained increasing attention in overcoming the limits of conventional injection molding (CIM) and improving the surface quality and mechanical properties of molded plastic products. In RHCM, the vario-thermal mold temperature control system is the key technique because it directly affects the molding Cycle time and the final part quality. In this study, a new RHCM technology with electric Heating and coolant cooling was studied in detail. Two different RHCM mold structures for a large LCD TV panel were proposed and designed. The numerical simulation method was used to analyze the thermal response of the mold cavity surface at the Heating stage and the thermal response of the resin melt at the cooling stage. The Heating/cooling efficiency of the proposed electric Heating RHCM system was evaluated. The thermal expansion analysis of mold cavity was implemented and the fixation of the cavity in molds was also optimized. The results showed that the electric-Heating mold with a separate cooling plate can efficiently enhance the Heating efficiency. The thermal expansion of the cavity surface can be reduced by increasing the alleviating-gap between the cavity and the cavity-retainer plate. Then, the service lifetime of the electric-Heating mold can be improved. A RHCM production line with electric Heating for the large LCD TV panel was constructed. Both the simulation and test production results indicate that the proposed electric Heating RHCM technique can realize high-temperature injection molding without increasing the molding Cycle time. The surface appearance of the LCD TV panels was dramatically improved and the surface marks that usually occur in CIM process were eliminated completely. Copyright © 2009 John Wiley & Sons, Ltd.
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fully coupled transient Heat transfer and melt filling simulations in rapid Heat Cycle molding with steam Heating
Polymer-plastics Technology and Engineering, 2011Co-Authors: Guoqun Zhao, Guilong Wang, Yanjin GuanAbstract:Rapid Heat Cycle molding (RHCM) is a novel injection molding technology, in which injection mold is rapidly Heated to a high temperature, usually higher than the glass transition temperature of the polymer material, before melt-injection and rapidly cooled down to solidify the shaped polymer melt in mold cavity for ejection. Since the elevated mold temperature can eliminate the unwanted premature melt freezing during filling stage, the melt flow resistance is greatly reduced and the filling ability of the polymer melt is also significantly improved. As a result, plastic parts with excellent surface appearance can be obtained. In this study, a three-dimensional numerical model coupled with Heat transfer analysis and melt-filling processes for RHCM with steam Heating was established. The thermal response analysis for the Heating stage of RHCM process was performed by solving Heat conduction equations. The Heat transfer analysis results right after the mold cavity surface is Heated up to the required tempera...
Xiaoxin Wang - One of the best experts on this subject based on the ideXlab platform.
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Heating cooling channels design for an automotive interior part and its evaluation in rapid Heat Cycle molding
Materials & Design, 2014Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed innovative injection molding technology. Rapid Heating and cooling of the injection mold is the most crucial technique in RHCM because it not only has a significant effect on part quality but also has direct influence on productivity and cost-efficiency. Accordingly, Heating and cooling system design plays a very important role in RHCM mold design. This study focuses on the Heating/cooling system design for a three-dimensional complex-shaped automotive interior part. Heat transfer simulation based on finite element analysis (FEA) was conducted to evaluate the thermal response of the injection mold and thereby improve Heating/cooling channels design. Baffles were introduced for Heating/cooling channels to improve Heating/cooling efficiency and uniformity of the mold. A series of thermal response experiments based on full factorial experimental design were conducted to verify the effectiveness of the improved Heating/cooling channels design with baffles. A mathematical model was developed by regression analysis to predict the thermal response of the injection mold. The effects of the cavity surface temperature on weld mark and surface gloss of the part were investigated by experiments. The results show that the developed baffle-based Heating/cooling channels can greatly improve thermal response efficiency and uniformity of the mold. The developed mathematical model supplies an efficient approach for precise predication of mold thermal response. As the cavity surface temperature raises to a high enough level, automotive interior parts with high gloss and non-weld mark surface can be obtained.
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research on the reduction of sink mark and warpage of the molded part in rapid Heat Cycle molding process
Materials & Design, 2013Co-Authors: Xiaoxin Wang, Guoqun Zhao, Guilong WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed innovative injection molding technology to enhance the surface quality of the plastic parts without extending the molding Cycle. Most of the common defects that occur in the plastic parts produced by conventional injection molding (CIM), such as flow mark, silver mark, jetting mark, weld mark, exposed fibers, short shot, etc., can be well solved by RHCM. However, RHCM is not a nostrum for all the defects in injection molding. Sink mark and warpage are two major defects occurring in RHCM. The purpose of this study is to investigate and further solve the sink mark and warpage of the molded parts in RHCM. To solve the problem of sink mark, a new “bench form” structure for the screw stud on the product coupling with a lifter structure for the injection mold was proposed. The external gas assisted packing was also proposed to reduce the sink mark in RHCM. To solve the problem of warpage, design of experiments via Taguchi methods were performed to systematically investigate the effect of processing parameters including melt temperature, injection time, packing pressure, packing time and also cooling time on the warpage. Injection molding simulations based on Moldflow were conducted to acquire the warpages of the plastic parts produced under different processing conditions. A signal to noise analysis was conducted to analyze the effect of the factors, and the optimal processing parameters were also found out. ANOVA was also conducted to quantitatively analyze the percentage contributions of the processing parameters on the warpage. The verification results show that part warpage can be reduced effectively based on the optimal design results.
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effects of cavity surface temperature on mechanical properties of specimens with and without a weld line in rapid Heat Cycle molding
Materials & Design, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract Rapid Heat Cycle molding (RHCM) is a recently developed injection molding technology to enhance surface esthetic of the parts. By rapid Heating and cooling of mold cavity surfaces in molding process, it can greatly alleviate or even eliminate the surface defects such as flow mark, weld line, glass fiber rich surface, silver mark, jetting mark, and swirl mark, and also improve gloss finish and dimensional accuracy without prolonging the molding Cycle. Besides surface esthetic, mechanical property is also a very import issue for the molded plastic part. The aim of this study is focusing on the effects of the cavity surface temperature just before filling, T cs , in RHCM on the mechanical strength of the specimen with and without weld line. Six kinds of typical plastics including polystyrene (PS), polypropylene (PP), acrylonitrile butadiene styrene (ABS), acrylonitrile butadiene styrene/polymethylmethacrylate (ABS/PMMA), ABS/PMMA/nano-C a CO 3 and glass fiber reinforced polypropylene (FRPP) are used in experiments. The specimens with and without a weld line are produced with the different T cs on the developed electric-Heating RHCM system. Tensile tests and notched Izod impact tests are conducted to characterize the mechanical strength of the specimens molded with different cavity surface temperatures. Simulations, differential scanning calorimetry (DSC), scanning electron microscope (SEM) and optical microscope are implemented to explain the impact mechanism of T cs on mechanical properties.
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experimental research on the effects of cavity surface temperature on surface appearance properties of the moulded part in rapid Heat Cycle moulding process
The International Journal of Advanced Manufacturing Technology, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:The influences of the cavity surface temperature just before filling on part surface appearance and texture in rapid Heat Cycle moulding are investigated. It is observed that the cavity surface temperature just before filling has a very significant influence on part surface appearance. As the cavity surface temperature increases, aesthetic quality of the moulded part can be greatly improved by reducing surface roughness, increasing surface gloss and reducing weld mark. There is a critical cavity surface temperature just before filling for each plastic material. As the cavity surface temperature reaches the critical value, the part surface appearance will reach the optimal level with lowest roughness, highest gloss and without any weld mark. The critical cavity surface temperature on surface gloss and roughness is close to the Vicat softening point of the plastic material. The critical cavity surface temperature on weld mark is 10–20 °C higher than that on surface roughness and gloss. The mechanisms for generating the rough surface of the part moulded with a low cavity surface temperature and improving part surface appearance by increasing cavity surface temperature are disclosed.
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Effects of cavity surface temperature on reinforced plastic part surface appearance in rapid Heat Cycle moulding
Materials & Design, 2013Co-Authors: Guilong Wang, Guoqun Zhao, Xiaoxin WangAbstract:Abstract The influences of the cavity surface temperature just before filling on surface appearance and texture of the moulded reinforced plastic parts in rapid Heat Cycle moulding (RHCM) are investigated. Two typical reinforced plastics including ABS/PMMA/nano-C a CO 3 and 20% fibre reinforced polypropylene (FRPP) are tested in experiments. The roughness, gloss and morphology of the part surface are characterized with white light interferometer, gloss meter, and optical microscope, respectively. It is observed that the cavity surface temperature just before filling has a significant influence on part surface appearance. With the increase of the cavity surface temperature just before filling, aesthetic quality of the moulded part can be greatly improved. There is a critical value of the cavity surface temperature just before filling for each plastic. As the cavity surface temperature reaches the critical value, part surface appearance will reach the optimal level with low roughness and high gloss. The weld mark for ABS/PMMA/nano-C a CO 3 has a V-shaped structure while that for FRPP has a hump-shaped structure. With the increase of the cavity surface temperature just before filling, the width of the V-shaped weld mark reduces gradually until it disappears completely while the height of the hump-shaped weld mark decreases firstly and then increases. The mechanisms for the improvement of surface appearance by increasing cavity surface temperature just before filling and the generation of the V-shaped and hump-shaped weld mark are disclosed.
Giovanni Lucchetta - One of the best experts on this subject based on the ideXlab platform.
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experimental analysis of mechanical properties and microstructure of long glass fiber reinforced polypropylene processed by rapid Heat Cycle injection molding
Composites Part A-applied Science and Manufacturing, 2018Co-Authors: Luca Crema, Marco Sorgato, Filippo Zanini, Simone Carmignato, Giovanni LucchettaAbstract:Abstract Rapid Heat Cycle molding (RHCM) of reinforced thermoplastics is increasingly used in order to obtain high surface quality on structural parts. In this work, the effect of RHCM on both microstructure and ultimate tensile strength of polypropylene reinforced with 30 wt% long glass fibers was investigated. Micro X-ray computed tomography was employed to allow a non-destructive assessment of fibers orientation and internal porosity, while optical measurements were used to evaluate the residual fibers length distribution. The experimental results indicated that an increase of injection velocity always results in a decrease of ultimate tensile stress, due to higher fiber breakage. This effect is partly attenuated at low mold temperature, due to an increase of fiber orientation. On the other hand, when using RHCM an increase of injection velocity results in a greater decrease of ultimate tensile stress, due to the reduction of both fiber length and fiber orientation.
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thermal optimization of deterministic porous mold inserts for rapid Heat Cycle molding
International Journal of Heat and Mass Transfer, 2017Co-Authors: Luca Crema, Marco Sorgato, Giovanni LucchettaAbstract:Abstract In this work a porous mold insert with a regular deterministic geometry was developed and its design was optimized by means of numerical simulations to maximize the Heat exchange in Rapid Heat Cycle Molding (RHCM) between water and the cavity surface, without impairing the mold structural integrity. Compared to previous fluid convection technologies, such as steam Heating and pressurized water in metal foam inserts, the optimized porous inserts performance is significantly higher, having a maximum Heating rate of 7 °C/s and a mean Heating rate of 6 °C/s. A testing mold with the optimized porous inserts was developed to validate the numerical simulations and to characterize the RHCM influence on the surface quality of fiber-reinforced polypropylene parts. Parts surface roughness decreases increasing mold temperature, packing pressure and injection rate. Moreover an increase of mold temperature attenuates the effect of injection rate on roughness. Therefore, with this RHCM technology it is possible to obtain a high quality fiber-reinforced part even at low injection speed.
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Influence of process parameters on the weld lines formation in rapid Heat Cycle molding
2011Co-Authors: M. Fiorotto, Giovanni LucchettaAbstract:The insufficient entanglement of the molecular chains at the v‐notch of a weld line impairs the mechanical strength and the surface quality of a plastic product. The rapid Heat Cycle molding technology (RHCM) has been recently used to enhance surface appearance of the parts, by thermally cycling the mold surface temperature. The mold temperature is the key of RHCM technology because it significantly affects productivity, energy efficiency and the quality of the final polymer part. In this work the influence of mold temperature on the weld lines depth and roughness were studied. Three different materials were tested. To investigate the influence of process parameters, a special mold insert was designed and manufactured. Weld lines geometry and roughness were quantitatively characterized by means of a profilometer. Experimental results show that is possible to increase the temperature to 10° C lower than the glass transition to obtain a high‐gloss parts without weld lines with a significant reduction of cyc...
