Active metal transfer control by utilizing enhanced droplet oscillation part II: Modeling and analysis

Enhanced active metal transfer control is experimentally studied in the first part of this investigation. Differing from the original active control, the enhanced active metal transfer control uses a modified current waveform, which increases the amplitude of the excited droplet oscillation and the needed detaching current is thus much more reduced. The experimental study reveals that strongest droplet oscillation and maximum enhancement on the droplet detachment require optimal selections of three waveform parameters: the exciting peak duration and exciting/detaching phase delay. In this study, a numerical model on the dynamic droplet oscillation and detachment is developed based on the mass-spring system. The spring constant and damping coefficient in the model are experimentally calibrated. Analysis on the effects of the key waveform parameters on the droplet oscillation/detachment gives a comprehensive understanding on the mechanism of the droplet excitation and detachment. Given other waveform parameters, the optimal value of the three key parameters can be calculated from the model. The accuracy of the model is verified by comparing the modeling results with the corresponding experimental ones. The modeling resuits suggest that the exciting phase delay and exciting peak duration can be fixed as long as the droplet size is controlled to be relatively small as desired by the drop spray transfer. In addition, an analytical model has been established through approximations, and its adequate accuracy in predicting the optimal detaching phase delay has also been verified.