Actuation waveform optimization via multi-pulse crosstalk modulation for stable ultra-high frequency piezoelectric drop-on-demand printing

Piezoelectric drop-on-demand inkjet printing is a widely used additive manufacturing technology, in which droplets are ejected from a piezoelectric printhead under certain actuation waveforms to form three-dimensional structures. The crosstalk generated by high- frequency multi-pulse actuation waveforms in the piezoelectric printhead has always been considered detrimental and needs to be suppressed, since it significantly limits the improvements of the working frequency of piezoelectric inkjet printing. Herein, the high- frequency multi-pulse crosstalk behaviors in a single nozzle of a piezoelectric printhead were investigated experimentally and numerically. The phenomenon of the droplet jetting state oscillating regularly with the increase of the pulse frequency was found to be controlled by the constructive/destructive interference mechanism of the multi-pulse crosstalk. The maximum frequency for stable droplet jetting could be obtained under the optimal constructive interference. Based on this mechanism, an actuation waveform optimization method via multi-pulse crosstalk modulation for stable ultra-high frequency piezoelectric drop-on-demand printing was explored. The results demonstrated that, under the optimized actuation waveform, the printhead used in this paper, which with a nominal working frequency less than 20 kHz, could achieve controllable and stable droplet jetting even at working frequencies up to 200 kHz. In other words, the jetting frequency was increased by more than 10 times. This work provides a new perspective for improving the efficiency of additive manufacturing processes based on the piezoelectric inkjet printing technology.