Abstract

Directed energy deposition is a class of additive manufacturing processes where focused thermal energy melts and fuses material being deposited on a part. This type of process is useful for making high performance parts, remanufacturing and repair, and for making multi-material parts. However, in systems where powder feedstock is used, only a fraction of the powder ends up in the part and the rest is usually wasted. Increasing the amount of powder captured in powder-fed directed energy deposition systems is the focus of this work. The proposed solution is to combine vibration powder dispensing and gravity-fed powder delivery systems to give very high levels of powder capture. Vibration powder dispensing involves positioning a capillary tube at the bottom of a powder hopper that will not allow flow under static conditions, then applying suitable vibration to dispense powder. Experimental and discrete element method simulation work will be performed to assess the effects of capillary size, hopper incline and vibration parameters on the outlet mass flow rate of 316L stainless steel powder. Gravity-fed powder delivery uses an inclined surface or tube to direct the powder from the dispensing system to its desired location. Experimental and discrete element method simulation work will be performed to assess the effects of tube size, tube length, inclination and mass flow rate on the trajectory and spread of 316L stainless steel powder. Desired outcomes of these experiments are a mass flow rate range of at least 1−5 g/min on a single vibrating capillary, 95% or better powder capture, and a reduced time to turn the powder flow on and off compared to a conventional system. Results show that the system is capable of consistent mass flow rates between 0.6 and 7.9 g/min, 95% powder capture efficiency and lower on and off times than the conventional system, meeting all research goals.

Library of Congress Subject Headings

Additive manufacturing; Powder metallurgy--Mechanical properties; Powder metallurgy--Thermal properties

Publication Date

5-15-2023

Document Type

Dissertation

Student Type

Graduate

Degree Name

Mechanical and Industrial Engineering (Ph.D)

Department, Program, or Center

Mechanical Engineering (KGCOE)

Advisor

Denis R. Cormier

Advisor/Committee Member

Iris Rivero

Advisor/Committee Member

Satish Kandlikar

Campus

RIT – Main Campus

Plan Codes

MIE-PHD

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