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7.07-2015
Potential use of decayed wood in production of wood plastic composite
Nadir Ayrilmisa a, Alperen Kaymakcia,Türker Güleçb b,
a Department of Wood Mechanics and Technology, Forestry Faculty, Istanbul University, Bahcekoy, Sariyer, 34473 Istanbul, Turkey; b Department of Chemistry and Technology of Forest Products, Forestry Faculty, Artvin Çoruh University, Artvin, Turkey
This study investigated the mechanical and thermal properties of hot press molded wood plastic composite (WPC) panels produced from different amounts (30, 40, or 50% weight) of Scots pine (Pinus sylvestris L.) wood decayed by brown-rot fungi and polypropylene with coupling agent (maleic anhydride grafted polypropylene, 3 wt%). The results were compared with the properties of WPCs produced with the sound wood. The holocellulose content of the decayed wood was found to be significantly lower than that of the sound wood. Although the flexural and tensile properties of WPCs produced with the decayed wood flour were lower than those of the WPCs produced with the sound wood flour, their thermal stabilities were better at the wood flour levels of 40 wt% and 50 wt%... read more
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7.07-2015
Effect analysis for compensating viscosity fluctuations by means of a self-optimising injection moulding process
Ch. Hopmann1, M. Weber1 and A. Reßmann1
1 Institute of Plastics Processing (IKV) at RWTH Aachen University, Germany; weber@ikv-aachen.de
As the conventional control of the injection moulding process is based on machine variables which cannot compensate process fluctuations, a constant part quality cannot be guaranteed. The aim of the self-optimising processing method is to compensate the effects of process fluctuations, to ensure a repeatable forming of the moulded part and therefore achieve a constant part quality. The so called pvT-optimisation allows, in combination with a closed-loop cavity pressure control, a systematic consideration of variable boundary conditions of the process. In addition, the effort required for setting up the process can be significantly reduced. The pvT-optimised processing method enables the compensation of thermal disturbances and pressure fluctuations... read more
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7.07-2015
Injection moulding of optical functional micro structures using laser structured, PVD-coated mould inserts
Ch. Hopmann1, M. Weber1, M. Schöngart1, C. Schäfer1, K. Bobzin2, N. Bagcivan2, T. Brögelmann2, S. Theiß2, T. Münstermann2 and M. Steger3
1 Institute of Plastics Processing (IKV) at RWTH Aachen University, Germany; weber@ikv-aachen.de, 2 Surface Engineering Institute (IOT), RWTH Aachen University, Aachen, Germany; 3 Fraunhofer Institute for Laser Technology (ILT), Aachen, Germany
Micro structured optical plastics components are intensively used i. e. in consumer electronics, for optical sensors in metrology, innovative LED-lighting or laser technology. Injection moulding has proven to be successful for the large-scale production of those parts. However, the production of those parts still causes difficulties due to challenges in the moulding and demoulding of plastics parts created with laser structured mould inserts. A complete moulding of the structures often leads to increased demoulding forces, which then cause a breaking of the structures and a clogging of the mould. An innovative approach is to combine PVD-coated (physical vapour deposition), laser structured inserts and a variothermal moulding process to create… read more
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7.07-2015
Micro Injection Moulding Process Parameter Tuning
Michael Packianatheraa, Christian Griffithsb, Wan Kadiraa
a State key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China; b College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, Devon, United Kingdom
This paper focuses on tuning the micro injection moulding process parameters. In this study four process parameters namely, barrel temperature, mould temperature, holding pressure and injection speed were considered. In order to capture their behaviour a L16 Orthogonal Array with two levels for each parameter was employed to produce the design of a 15 mm x 20 mm x 1 mm microfluidic platform using Cyclic Olefin Copolymer (COC), a common polymer. The demoulding force was measured during the micro injection moulding process.... read more
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28.05-2015
Investigation into mechanical and microstructural properties of polypropylene manufactured by selective laser sintering in comparison with injection molding counterparts
Wei Zhua, Chunze Yana,b, Yunsong Shic, Shifeng Wena, Jie Liua, Yusheng Shia
a State key Laboratory of Materials Processing and Die & Mould Technology, Huazhong University of Science and Technology, Wuhan 430074, China; b College of Engineering, Mathematics and Physical Sciences, University of Exeter, Exeter EX4 4QF, Devon, United Kingdom; c Guangdong Silver Age Sci & Tech Co. Ltd, Dongguan 523927, China
This work evaluated the processibility of a low-isotacticity polypropylene (PP) powder by selective laser sintering (SLS), and systematically analyzed and compared the melting and crystallization characteristics, crystalline structure, tensile properties and thermo-mechanical properties of the PP specimens fabricated by SLS and injection molding (IM). The results show that the PP powder has a nearly spherical shape, smooth surfaces, appropriate particle sizes, a wide sintering window and a low degree of crystallinity, consequently indicating good SLS processibility. In SLS, the molten PP continues to maintain at a high part bed temperature until the whole manufacturing process finished, thus demonstrating a low cooling rate. This gives... read more
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28.05-2015
Reducing ghost marks in injection-molded plastic parts by using external gas-assisted holding pressure
Heng-Yi Sua, Shih-Chih Nianb, Ming-Shyan Huanga
a Department of Mechanical and Automation Engineering, National Kaohsiung First University of Science and Technology, 2 Jhuoyue Rd, Nanzih, Kaohsiung City, 811, Taiwan, ROC; b Department of Power Mechanical Engineering, National Taitung Junior College, 889 Jhengci N. Rd., Taitung City, 95045, Taiwan, ROC
Ghost marks are gloss-related defects in injection-molded plastics that cause uncertain visual darkness depending on the viewing angle. Conventionally, these minor defects are not substantial, but they cannot be overlooked when they diminish the appearance quality of plastic parts such as dashboards in luxury automobiles. This work investigated the causes and effects of ghost marks through experimental observations of a tensile-test sample, which was assessed to determine the improvement of its appearance quality with respect to processing parameters including mold and melt temperatures as well as injection speed and pressure. To reduce defects... read more
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28.05-2015
Iso and variothermal injection compression moulding of polymer micro- and nanostructures for optical and medical applications
C Rytka1, P M Kristiansen1 and A Neyer2
1 University of Applied Sciences and Arts Northwestern Switzerland (FHNW), School of Engineering, Institute of Polymer Nanotechnology (INKA), 5210 Windisch, Switzerland; 2 Dortmund University of Technology, Faculty of Electrical Engineering, AG Mikrostrukturtechnik, Dortmund D-44227, Germany
The surfaces of medical and optical polymer products are being increasingly functionalized with micro- and nanostructures using mass replication methods like injection moulding. We compared the filling behaviour and replication quality of such structures using four different moulding processes with two polymers of different viscosity and wetting behaviour. For this purpose, we replicated three representative 2D and 3D micro- and nanostructures into polymethylmethacrylate and amorphous polyamide by isothermal and variothermal injection moulding with and without compression, respectively, using the same mould. The parallel compression phase reduced the internal pressure in the cavity, leading to fewer demoulding issues but without significant influence on the replication fidelity. Variothermal heating of the mould in combination with a polymer of low viscosity and good wetting behaviour was favourable especially for filling of high aspect-ratio structures. For microstructure replication, melt viscosity and no-flow temperature were clearly more relevant than… read more
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9.05-2015
Heat Flow Analysis and Efficiency Optimization of Rotational Molding Equipment for Large Plastic Products
L. Qin1,2, Y.-M. Ding1,2, G.-C. Zhu3, H.-C. Yu3,2 and W.-M. Yang1,2.
1 College of Mechanical and Electrical Engineering, Beijing University of Chemical Technology, Beijing, PRC; 2 Key Laboratory of Automobile Plasticizing Equipment Manufacturing, Beijing, PRC; 3 Wenling Rising Sun Rotational Molding Technology Co., Ltd., Wenling, PRC
There exists an important relationship between the temperature fields and the heat utilization efficiency in the oven of rotational molding equipment. If the temperatures at the main locations can be reasonably controlled, then the efficiency of the rotational molding machine can be effectively improved. The main objective of this research project is to carry out numerical simulation and analysis of the velocity field and temperature field in the oven of a shuttle-type rotational molding machine by using the commercial code FLUENT. The machine was selected as the research object owing to its uneven temperature fields and large energy wastage. The simulation results were then verified by experiments. By improving the structure of the outlets of rotational molding machine and by… read more
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19.04-2015
Improving the Quality and Productivity of Molded Parts with a New Design of Conformal Cooling Channels for the Injection Molding Process
Shayfull Zamree Abd Rahim1, S. Sharif1, Azlan Mohd Zain2, Shayfull Zamree Abd Rahim3, S. M. Nasir3, Shayfull Zamree Abd Rahim4, S. M. Nasir4 Andr. Mohd Saad5
1 Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, 81310 Skudai, Johor, Malaysia; 2 Soft Computing Research Group, Faculty of Computing, Universiti Teknologi Malaysia, UTM Skudai, Johor, Malaysia; 3 Green Design and Manufacture Research Group, Center of Excellence Geopolymer and Green Technology (CEGeoGTech), Universiti Malaysia Perlis, Kangar, Perlis, Malaysia; 4School of Manufacturing Engineering, Universiti Malaysia Perlis, Arau, Perlis, Malaysia; 5 Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, UTM Skudai, Skudai, Johor, Malaysia
In materials processing, quality and productivity are notably important and must be controlled for each product type produced. In the injection molding process, quality is measured as the extent of warpage of molded parts and productivity is measured in terms of the molding cycle time. This paper presents a new design of milled grooved square shape (MGSS) conformal cooling channels, which provide more uniformity in cooling with a larger effective cooling surface area compared to circular and other types of cooling channels with a similar cross-section. This study examined the warpage of molded parts, and the cooling time, which affected the molding cycle time…read more
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24.03-2015
Measurement and Numerical Simulation of Void and Warpage in Glass Fiber Reinforced Molded Chunky Parts
S. Kleindel1, D. Salaberger2, R. Eder3, H. Schretter3 and C. Hochenauer1
1 Institute of Thermal Engineering, Graz University of Technology, Graz, Austria; 2 University of Applied Sciences Upper Austria, Wels, Austria; 3 HTM Sport GmbH, Schwechat, Austria
The aim of this paper is to determine the reason for the large warpage of an injection molded chunky part made of glass fiber reinforced polyamide 6. State of the art commercial 3D injection molding simulation software was used to predict the warpage of the part. While the simulation predicted a product virtually free of warpage the molded parts showed a large deformation. Several molding experiments and X-ray computed tomography (μCT) scans of the moldings have been performed to figure out the reason for this. The μCT scans revealed voids in the thick walls of the part…read more
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24.03-2015
Evaluation of heat transfer coefficient between polymer and cavity wall for improving cooling and crystallinity results in injection molding simulation
Yao Liu, Michael Gehde
Chemnitz University of Technology, Department of Mechanical Engineering, D-09107 Chemnitz, Germany
Heat transfer coefficient (HTC), as a parameter that describes the thermal transfer ability of the interface between the polymer melt and the metallic wall, has a dominant role in calculating temperature distribution. This research focuses on evaluating the HTC between the polymer and the cavity wall for improving the cooling and crystallinity simulation. A mathematical model for evaluating HTC was presented. Injection molding experiments were carried out to obtain temperature data near the cavity wall; HTC was calculated after data processing…read more
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24.03-2015
Correlation between runner pressure and cavity pressure within injection mold
Kuo-Ming Tsai, Jun-Kai Lan
Department of Mechanical Engineering, National Chin-Yi University of Technology, Taiwan, Republic of China
Cavity pressure in the injection molding process is closely related to the quality of the molded products and is used for process monitoring and control to upgrade the quality of molded products. However, the sensor installed inside the cavity makes the molded product of the cavity defective, reducing productivity. In view of this, this study investigates the correlation between melt pressure and cavity pressure in different runner positions and determines the appropriate runner position, where the runner pressure can represent the cavity pressure, in order to increase productivity…read more
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10.02-2015
Spiral and Conformal Cooling in Plastic Injection Moulding
Yu Wanga, Kai-Min Yua, Charlie C.L. Wangb
a Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hong Kong; b Department of Mechanical and Automation Engineering, The Chinese University of Hong Kong, Hong Kong
Designing cooling channels for the thermoplastic injection process is a very important step in mold design. A conformal cooling channel can significantly improve the efficiency and the quality of production in plastic injection molding. This paper introduces an approach to generate spiral channels for conformal cooling. The cooling channels designed by our algorithms has very simple connectivity and can achieve effective conformal cooling for the models with complex shapes. The axial curves of cooling channels are constructed on a free-form surface conformal to the mold surface…read more
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10.02-2015
Numerical shape optimization as an approach to reduce material waste in injection molding
Mario Studer, Frank Ehrig
IWK Institute for Materials Sciences and Plastics Processing, University of Applied Sciences, Rapperswil, Switzerland
Reducing material waste is a major issue during new product development, especially for injection-molded parts, where the wall thickness has a strong influence on molding times and therefore on the manufacturing cost. Finding the minimum material amount for producing high-quality products is a difficult and time-consuming task using state-of-the-art computer-aided engineering CAE tools. In this study, a numerical procedure is presented to reduce the material amount required for injection-molded parts by optimizing their wall thickness distributions with respect to part quality and identifying an upper limit for the injection pressure…read more
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10.02-2015
Warpage control of thin-walled injection molding using local mold temperatures
Shih-Chih Niana, Chih-Yang Wub, Ming-Shyan Huangb
a Department of Power Mechanical Engineering, National Taitung Junior College, Taitung City, Taiwan;
b Department of Mechanical and Automation Engineering, National Kaohsiung First University of Science and Technology, Kaohsiung City 811, Taiwan
Currently, 3C products are required to be lightweight, portable, and convenient. Injection molding is among the most used techniques for mass production in plastic processing industries; however, producing thinner parts that do not warp is challenging. Although plastic components warp for numerous complicated reasons, warpage primarily is caused by variations in shrinkage during the injection process of plastic part manufacturing. Material properties, part design, mold design, and processing conditions are factors influencing variations in the part shrinkage. For example, inconsistent thickness in component geometry, poor sprue–runner–gate or cooling design in the injection mold, and improper molding condition settings may cause plastic parts to warp excessively…read more