Design of a gas atomising system capable of producing suitable aluminium powder for Selective Laser Melting (SLM) process

Abstract

Documentation on the correct process parameters and component requirements for setting up efficient aluminum powder production systems capable of manufacturing powder that meets the requirements for the selective laser melting (SLM) process is not available due to its proprietary nature. This hinders powder metallurgy (PM) trainees in acquiring knowledge and skills needed in setting up such metal powder production systems. To address this challenge, powder requirements for the SLM process and powder production techniques for manufacturing metal powder that meets SLM requirements were identified and defined via literature review. User-value analysis (UVA) and cost–benefit analysis (CBA) techniques were applied as evaluation tools to identify the best components and process parameters for aluminum powder production via gas atomisation. A conceptual design framework for setting up an aluminum powder gas atomizing system which meets SLM requirements is developed with a view to improving the delivery of PM education in developing countries as trainees gain knowledge and skills for setting up powder production systems. The outcome of the conceptual design framework suggests that powdered particles obtained from gas atomisation technique meets the SLM requirements. Therefore, the mechanical design of the components of the metal powder gas atomiser was carried out via empirical relations. Components of the metal powder gas atomiser designed include a 5kg/hr melting and holding induction furnace, close-coupled nozzle and the atomising chamber. A parametric design of the nozzle was carried out via computational fluid dynamics (CFD) by exploring how aspect ratio (throat area and expansion area) influence gas velocity required during high pressure gas atomization (HPGA). Outcomes of CFD analysis indicate that maximum velocity (2880 m/s) was attained at expansion length of 2.0 mm and throat diameter of 0.35 mm, hence the configurations were adopted for this research.