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Resolution Improvement of a Resin 3D Printer via an Optical System and Adjusting the Affective Parameters of Light on the Curing Accuracy for Micro-scale 3D Fabrication

Dadkhah, Kayvan | 2024

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 57811 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Mohammadi, Kaivan
  7. Abstract:
  8. Nowadays, with the increasing need to design and manufacture parts with dimensions less than 1 millimeter in various fields such as medicine, drug delivery, microfluidics, precision casting, and many other areas, methods for manufacturing such parts have gained significant attention. Numerous studies have been conducted to develop 3D printing methods for manufacturing increasingly smaller parts, with optical 3D printing research being at the forefront. In this regard, researchers have enabled the achievement of smaller parts by developing in three areas: increasing the resolution of the light source, changing the resin compositions, and improving the accuracy and correction of image pixels. Given that no research has been conducted so far to upgrade commercial 3D printers for manufacturing micron-sized parts, and all previous studies where micron-sized parts were made with 3D printers, used custom or special resins, the aim of this project is to improve the resolution of a commercial 3D printer based on digital light processing technology by designing an optical system for it, so that micro-scale parts can be manufactured using commercial resins with this printer. In this regard, first, by understanding the optical structure of the device's light source, an optical assembly for image reduction was designed and implemented. To save costs, the main part of the optical assembly was selected from the device's own components. By using this system, the image resolution, which is one of the most important parameters determining the accuracy of part manufacturing, was improved from about 40 microns in the initial device to about 5 microns. After improving the image resolution, due to the reduction and concentration of light energy, the image energy was adjusted using neutral density filters. Then, the printing parameters, including image brightness, color contrast, and light exposure time, were adjusted to appropriate levels through power and optical spectrum tests and trial and error. Based on this, the minimum brightness intensity, color contrast at a relative level of 75%, and light exposure time of about 2.5 seconds were set. After that, the effect of light power versus light exposure time was examined, and based on the results of this examination, for a fixed amount of energy applied to the resin, lowering the power and consequently increasing the exposure time creates a more suitable condition; because in this state, the sensitivity of manufacturing accuracy to time changes, which may occur as errors in the control system, is minimized. Finally, various parts, including microstructures such as LIGA process molds with wall thicknesses less than 15 microns, drug delivery microneedles with tip diameters less than 10 microns, and also desired 3D parts with details smaller than 100 microns, were manufactured and presented
  9. Keywords:
  10. Additive Manufacturing ; Three Dimentional Printing ; High Resolution ; Commercial Resin ; Resolution Enhancement ; Microstructure

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