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Fabrication of Micron Resolution Polymer Structures with Electrohydrodynamic Printing
Shahverdi, Mohammad | 2021
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- Type of Document: M.Sc. Thesis
- Language: Farsi
- Document No: 55025 (08)
- University: Sharif University of Technology
- Department: Mechanical Engineering
- Advisor(s): Movahedi, Mohammad Reza
- Abstract:
- In recent years, additive manufacturing has been widely used in prototyping and production of industrial-commercial pieces. Additive manufacturing or three-dimensional (3D) printing is able to easily produce any piece for initial prototyping, no matter how complex it is. The fused deposition modeling (FDM) is a type of additive manufacturing process that produces the piece with the mechanism of feeding the PLA filament, then the molten polymer extrusion and depositing the fluid layer by layer with a high viscosity. Since the thickness of the layers is directly proportional to the diameter of the nozzle and the diameter of the used nozzles cannot be in the micron range (lower than 100 micrometer), low resolution is one of the most fundamental limitations of FDMs. On the other hand, electrohydrodynamic (EHD) printing mechanism is capable of printing in micron range. As its most significant cabability, this mechanism can minimize the ink released by applying an electronic field between the nozzle and the substrata surface. The significance of this study is to investigate how to overcome the limitations of the FDM method and the ability to print in micron dimensions by combining the FDM printing method with EHD process to achieve high resolution. The basis of this research is applying high voltage (2-5 kilovolt) to the FDM nozzle in order to allow the formation of thin ink released for printing. For this purpose, the installation of high voltage application system at the output device, to prevent the transmission of electoral current to of the FDM other parts of the device, isolation and redesign of the device head were examined by various methods and the most reliable one was chosen. By making an isolated head, the primary experiments were done in order to specify the electronic field impact on the molten polymer, and to determine the effective applied voltage. Based on Taguchi method, then, some experiments were designed and done in order to achieve the optimal parameters. By observing the results of the experiments, two parameters of lines width and continuity of printed lines were considered as the experiments outputs. After analyzing the results, the optimal parameters were determined by applying 3000 volts voltage, creating a powerful electronic field, using a 300 micron nozzle, setting printer temperature on 230 degree centigrade and setting printer speed on 10 mm/s with a 75% current rate. In the end, it was revealed that the printed lines width decreased 70 percent in comparison to the normal condition.
- Keywords:
- Fused Deposition Modeling (FDM) ; Electrohydrodynamic ; Polylactic Acid ; Scaffold ; Electrohydrodynamic Printer ; Three Dimentional Printing
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