On precision droplet-based net-form manufacturing technology

Abstract: High-precision droplet-based net-form manufacturing of structural components is gaining considerable academic and industrial interest owing to the promise of improved component quality resulting from rapid solidi®cation processing and the economic bene®ts associated with fabricating a structural component in one integrated operation. A droplet-based net-form manufacturing technique is under development by the authors which is termed precision droplet-based net-form manufacturing (PDM). As the technique exploits the capillary instability phenomenon of liquid jets for producing uniform liquid metal droplets, it allows for a greater control of the thermal state and mass ¯ux of the droplets and thus the microstructure of the deposit can be readily tailored. The principle and the associated technical issues are described and discussed in detail in this paper. Recent progress in the development of PDM is also presented. The preliminary results demonstrated the following four important facts: (a) molten aluminium droplet streams can be generated on a repeatable basis and travel 50.0 cm in an inert environment with little degradation in stream stability, (b) components of signi®cant size can be fabricated (i.e. the horizontal square tube is 11.0 cm in height), (c) fully dense components can be fabricated with no post-treatment and (d) measured hardness is consistently higher than the raw stock