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Multiphysics Modeling and Magnetic Control of Powder Deposition Process in DMD Method of Additive Manufacturing Technology

Nejati Eghteda, Sina | 2021

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53755 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Movahhedy, Mohammad Reza
  7. Abstract:
  8. Direct Metal Deposition is one of the methods of Additive manufacturing that has seen the most spread in recent years. In this method metal powder is directed towards the free surface of the workpiece through a nuzzle, and is simultaneously heated to become molten in a melting pool by a laser beam and begins the deposition process. One of the parts that make up a DMD system is powder feeding nuzzle. These nuzzles usually encounter a similar fundamental problem: that the effect of gravity on the stream of metal powder and the carrier fluid causes this stream to deviate from its intended position. To prevent this, nuzzles are usually designed with a fixed downward angle and the angle of the nozzle slope is also high. This, however, limits the movement of the nuzzle and so limits the capabilities of the system. In order to tackle the mentioned problem, the following suggestion is introduced in this project: application of magnetic fields on particles to negate gravity. This design is reviewed by simulating a comprehensive model in COMSOL Multiphysics software. The combination of three modules of particle tracking, fluid flows and Magnetic field in this software makes this simulation possible. The results of the simulation show the preferred operation of the DMD system in different situations under the influence of magnetic fields affecting the stream of powder. These results are then considered and discussed under the criteria of the speed of carrier gas and the particles, the focus points of the powder density and the forces affecting the particles. For a cladding head working at 90° angle the deviation of the particle cluster in each nozzle of the head at the substrate’s is reduced by up to 90%. additionally, cladding with the carrier gas flow rate of 34% of the standard gas flow rate has become possible with only 20% deviation
  9. Keywords:
  10. Additive Manufacturing ; Direct Metal Deposition ; Powder Nozzle ; Multiphysics Modeling ; Powder Deposition

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