Experimental investigation of magnetostrictive DoD inkjet head for droplet formation

This paper presents the experimental characterization of jetting performance of the magnetostrictive DoD inkjet head (M-Jet). Firstly, the developed M-Jet is explained briefly, and the selection process of the driving waveform for the M-Jet is described. Then, the experiments are performed to investigate the jetting performance of the M-Jet. Finally, the experimental results are presented and discussed. A bipolar waveform is selected as the basic driving waveform for the M-Jet, which consists of an inflow time, an ejection time, a holding time, and a breakup time. Input current of ±1.8 A is selected and used for the rest of the experiments due to the shortest holding time. Both droplet speed and droplet volume increase linearly as the input current increases. It will be good to reach a higher droplet speed, but a lower volume. Therefore, it will be needed to find tradeoff between two in the future. The droplet formation is not successful up to a holding time of 300 μs, and becomes successful with further increase of the holding time to 360 μs. Then, the tail becomes longer with further increase of the holding time. The designed driving waveform applied to the M-Jet has the inflow time of 370 μs, ejection time of 10 μs, holding time of 360 μs, and breakup time of 10 μs. It generates one main droplet without any satellite droplet at the time of 900 μs. At this time, the droplet speed is about 3.5 m/s with the droplet diameter of 170 μm, resulting in calculating the droplet volume as 2.57 nL.