Experimental study of the piezoelectric drop-on-demand drop formation in a coaxial airflow

Abstract

One of the main issues in piezoelectric inkjet (PIJ) printing is the formation of satellite drops which can result in a degradation of print quality and failure of functional device. This work to this purpose is seeking a new solution to reduce or even eliminate the satellite in PIJ by designing a coaxial airflow-assisted piezoelectric drop-on-demand droplet generator for aqueous solutions and investigating the droplet jetting behavior in coaxial airflow under different operating conditions. Effects of waveform parameters in combination to the impact of the coaxial airflow pressure on the pinch-off, breakup/recoil of the free liquid thread, as well as formation and recombination of the primary drop and satellite are analyzed. Decrease of the length and velocity of liquid thread at pinch-off with the increase of coaxial airflow pressure has been observed, while the pinch-off time is independent of the coaxial airflow pressure. The coaxial airflow can facilitate the delay or elimination of breakup of the free-flying liquid thread as well as the recombination of the satellite with the primary drop. The results of this study indicate the proposed method could be a promising way of reducing satellite drops in piezoelectric inkjet printing.