Powder reuse in laser metal deposition phase III - part 2 : feasibility and sustainability

• Main Author: Han, Wen Siew
• Other Authors: Matteo Seita
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2021
• Subjects: Engineering::Materials::Material testing and characterization; Engineering::Mechanical engineering
• Online Access: https://hdl.handle.net/10356/150850
• Institution: Nanyang Technological University

Laser Metal Deposition is an additive manufacturing technique that is well-known for producing near-net-shape components with intricate geometries. However, a prevalent issue is its low powder usage efficiency, for which a substantial amount of blown powder is undeposited and disposed after. A potential solution to this problem is to reuse the collected powder, in order to reduce costs and mitigate the detrimental impact to the environment. However, there are concerns that the integrity of the fabricated build may be compromised due to possible contamination of the powder, which in turn affects its properties. Therefore, the primary objectives of this project were to study the reusability of Ti-6Al-4V Grade 23 powder in an LMD process and the environmental sustainability of powder reuse. A total of three cycles of build fabrication was conducted, with the use of virgin powder for the first cycle, and reusable powder collected from the previous cycle for subsequent cycles. Characterisation tests were conducted on the powder and builds from every cycle for analysis. For the sustainability analysis, the raw power usage, embodied energy, CO2) footprint and water usage were used as measures for the environmental performance. The results showed that the average porosity of the builds decreased across the cycles, which suggested that the integrity of the builds was not compromised. The chemical composition and flowability of the powder were not significantly affected despite reusing it for Cycles 2 and 3. There was no observable trend in the porosity of the powder across the cycles. It was noted that the powder from Cycle 3 had an exceptionally higher porosity level. The environmental sustainability analysis showed that there was significant amount of savings if the powder was reused, therefore promoting powder reuse in LMD as a sustainable measure in the long run.